key: cord-0882904-ljuni2ky
authors: Thakur, Preeti; Chahar, Deepika; Taneja, Shilpa; Bhalla, Nikhil; Thakur, Atul
title: A review on MnZn ferrites: Synthesis, characterization and applications
date: 2020-04-07
journal: Ceram Int
DOI: 10.1016/j.ceramint.2020.03.287
sha: e982ac0b7fed6d5b0bfbefb4ce7bb3e1f2375d19
doc_id: 882904
cord_uid: ljuni2ky

Researchers are taking great interest in the synthesis and characterization of MnZn ferrites due to their wide range of applications in many areas. MnZn ferrites are a class of soft magnetic materials that have very good electrical, magnetic and optical properties. The properties of MnZn ferrites include high value of resistivity, permeability, permittivity, saturation magnetization, low power losses and coercivity. The above mentioned advantageous features of MnZn ferrites make them suitable for the use in various applications. In biomedical field these ferrites are used for cancer treatment and MRI. MnZn ferrites are also used in electronic applications for making transformers, transducers and inductors. These ferrites are also used in magnetic fluids, sensors and biosensors. MnZn ferrite is highly useful material for several electrical and electronic applications. It finds applications in almost every household appliances like mobile charger, LED bulb, TV, refrigerator, juicer mixer, washing machine, iron, microwave oven, mobile, laptop, desktop, printer and so on. Therefore, the present review focuses on different techniques for synthesis of MnZn ferrites in literature, their characterization tools, effect of doping on the properties of MnZn ferrite and finally we will discuss about their applications.

In the past decade MnZn have attracted a large amount attention in academia due to its advantageous features that make MnZn ferrites suitable to be used in many applications of daily life. The data of the publications of the MnZn ferrites by SCOPUS in the last decade is shown in the figure 2. The record of the data shows that there is regular increase in the publications of the MnZn ferrite documents in last ten years and much more progress in publications may be seen in year 2016 and 2018. [88] [89] [90] [91] [92] and sintering conditions [93, 94] changes the magnetic, electrical properties and structural properties of nanoferrites which led to its wide range of applications. In addition, the shape, morphology, electrical, magnetic properties are affected by the cation distribution in the MnZn ferrite [95] . Cationic distribution for Mn 1-x Zn x Fe 2 O 4 is described in Table 2 . Considering the importance of Mn-Zn ferrites for various applications, a comprehensive review based on 261 references is summarized.

The main purpose of the review is to focus on the synthesis, morphology, properties and characterization methods of MnZn ferrites. While the subject of magnetic nanostructures is enormously wide and a large number a good review articles are published on magnetic nanoparticles, MnZn ferrites in particular constitutes a special niche of nanoparticles because of immense interest of the scientific community in soft ferrites. In addition, this review critically analyses methods and discusses on the choice of synthesis method for use of MnZn in a given application. In brief methods such as sol-gel method [96] [97] [98] [99] [100] [101] , co-precipitation method [85, [102] [103] [104] [105] [106] [107] [108] [109] , conventional ceramic technique [110, 111] , hydrothermal method [112] [113] [114] , citrate precursor method [115] [116] [117] , solid state reaction method [118] , auto-combustion method [119] and microemulsion method [120] for the synthesis of MnZn are discussed. Various advantages and disadvantages of the synthesis methods are shown in Table 1 .

MnZn ferrites have spinel structure [121] . The spinel structure has one major unit cell composed of 8 sub-unit cells having face centered cubic (FCC) structure with two types of sites in each unit cell i.e. tetrahedral (A) site and octahedral (B) site in the complete structure of MnZn ferrite. There are 64 tetrahedral interstitial sites and 32 octahedral interstitial sites. Spinel structure has closed packed oxygen atoms arrangement in which 32 oxygen atoms form a unit cell. Tetrahedral (A) sites are surrounded by four nearest neighbor oxygen atoms and octahedral (B) sites have six nearest oxygen atoms around it as shown in figure 4 . In MnZn spinel lattice, Zn ions are on the tetrahedral sites while Fe and Mn ions occupy both tetrahedral and octahedral sites. Due to this spinel structure, different metallic ions can be introduced that cause change in the electric and magnetic properties of ferrites. The metal ions introduced may enter the spinel crystal lattice by replacing Fe 3+ ions and leading to aggregation of these ions on the grain boundary. These morphological features suggest that the properties of MnZn ferrite nanoparticles can be tuned as long as the nanoparticle designer is specifically for a given application choose appropriate synthesis and characterization techniques for MnZn ferrites. In order to know the best advantages of MnZn ferrites for various applications, one has to be aware of different synthesis and characterization techniques.

MnZn ferrites are preferred over other ferrites due to their low cost and wide range of applications. These ferrites are very important for stress insensitivity and low noise and are generally used for applications where frequency requirements are below 2 MHz. MnZn ferrites are also advantageous due to their almost zero magnetocrystalline anisotropy.

In the class of soft ferrites, MnZn ferrites are preferred due to high permeability [122] [123] [124] [125] [126] [127] , saturation induction [128] [129] [130] , low power losses [34, [131] [132] [133] [134] [135] [136] [137] [138] and high magnetic induction [139, 140] . MnZn ferrites are of great interest due to their wide range of applications such as hyperthermia applications [141] , power applications [109] [110] [111] , magnetic fluid [145] , high frequency power supply, memory storage devices, TV sets, biomedicines [146] , magnetic resonance, catalysis etc. There is a continuous progress in the size and shape control of MnZn ferrites and also on the morphological and magnetic properties of MnZn ferrites by using different methods [147] of synthesis like sol-gel method [96] [97] [98] , co-precipitation method [85, [102] [103] [104] [105] [106] [107] [108] [109] 143] , conventional ceramic technique [110, 111] , hydrothermal method [112] [113] [114] [148] [149] [150] , citrate precursor method [115] , solid state reaction method [118] , autocombustion method [119, 151] , microemulsion method [120] . The effect of doping on the structural and magnetic properties of pure MnZn ferrites is also taken into account.

There are two approaches to synthesize nanoparticles: top-down and bottom-up. Both these approaches are shown in figure 5 . In top-down, a bulk material is broken down to get nanosized particles. This method has many limitations like generally metal oxides are used, requirement of very high temperature for the reaction, products are inhomogeneous, presence of impurities, crystal defects, broad size distribution and imperfection in surface structure. In bottom-up approach, small atomic building blocks fit together to produce nanoparticles. This is most favorable method for nanoparticles synthesis as the products in this method are homogeneous, highly pure and have narrow size distribution. Various synthesis techniques are used to prepare MnZn ferrite nanoparticles [152] [153] [154] [155] [156] [157] [158] [159] [160] such as sol-gel mthod [161] [162] [163] [164] , polyol process [165] ,co-precipitation method [104, 166, 167] , hydrothermal method [113] , citrate precursor method [122] , solid state reaction method [118] , auto-combustion method, ceramic processing method [139] . The techniques to synthesize MnZn ferrites are shown in figure 6 . By doping other elements or oxides [168] [169] [170] [171] the structural, electrical and magnetic properties of MnZn ferrite can be enhanced. For instance, Zaspalis et al. [172] observed that there was 17% improvement in the total power loss per volume when doping was done of Nb 2 O 5 in pure MnZn ferrite. After doping there was reduction in the losses related to magnetostriction and stress related hysteresis losses. Also, the eddy current losses related to electrical resistivity were also reduced. Xiang et al. [173] prepared MnZn ferrite particles with Ce 3+ doping and observed that no impurity phase was detected in the XRD pattern. It confirmed that Ce ions entirely got dissolved in spinel structure. This also led an increase in the saturation magnetization and decrease in the coercivity of MnZn ferrites, leading to an overall improvement in the soft magnetic properties of the material. Some methods of synthesis are described below.

Microwave is a form of electromagnetic energy associated with electromagnetic field. It can be defined as an electromagnetic wave having frequency and wavelength between 300 MHz and 300GHz in 1m to 1mm range respectively. While the study of microwaves started during 1930s, the first work on microwave hydrothermal synthesis of nanoparticles was demonstrated by Dr. Komarneni et al. while distinguishing the traditional hydrothermal synthesis methods [174] from microwave hydrothermal synthesis [175] [176] [177] . In microwave hydrothermal method, heat required in synthesis process is generated by microwaves which have the advantage of high penetrating power. Microwaves can penetrate and heat the sample to a certain depth. Microwave hydrothermal method is beneficial as it has very fast heating rates to allow generation of uniform nanomaterials with fine particle size distribution. Hence, this is faster cleaner and economical method as compared to traditional hydrothermal method [178] . Praveena were dissolved in 50ml de-ionized water. In this process pH was maintained at about 9.4.Thereafter the mixture was sealed in tetrafluorometoxil (TFM) and was put in microwave oven for 30min at 160℃ followed by washing of the solids with de-ionized water and ethanol several times. The resulting wet mixture was dried and then polyvinyl alcohol (PVA) was added that acts as a binder. The powder was then pressed into pellets followed by sintering at 900℃ for 30 min.Single phase spinel structure was confirmed by the XRD spectra.

The hydrothermal method is used for the preparation of ferrite nanoparticles on a large scale. Essentially, in this method the yield of nanoparticles is very high. If the parameters such as temperature, pressure and reaction time are properly selected, good quality nanoparticles can be synthesized. Phong et al. [112] studied magnetic properties and specific absorption of Mn 0.3 Zn 0.7 Fe 2 O 4 nanoparticles. In this work the MnZn ferrites were prepared by a hydrothermal process in a Teflon-lined stainless steel autoclave. The starting materials FeCl 3 , MnCl 2 , ZnCl 2 were dissolved in HCl solution and NaOH was slowly added to the solution and stirred for 30 min. The solution was transferred to Teflon-lined stainless steel autoclave till it was 80% full. The autoclave was heated at 180℃ for 12h and then left for cooling to room temperature. After that the products were washed many times with hot de-ionized water and acetone and finally dried in an oven at 80℃ for 5h.By this method, large quantity of ferrite nanoparticles can be synthesized. The nanomaterials prepared by this method have controlled size and this method requires aqueous media for the synthesis. But this method has some limitations that include requirement of special reactor, need of high pressure and high temperature.

Co-precipitation [180] is an easy and conventional method to synthesize nanomaterials. The ferrites prepared using this method are of controlled size, highly pure and have homogeneous structure. Typical co-precipitation method for synthesis of nanoparticles is shown in figure  7 .Normally inorganic salts (nitrate, chloride, sulfate, etc.) are used in this method as the starting materials that are dissolved in water or any other medium which is suitable to form a homogeneous solution. The pH of the solution is adjusted to 7-9 and the solvent is evaporated to get nanoparticle precipitates. It should be noted that the concentration of salt, temperature, pH and the rate of pH change are detrimental to crystal growth and aggregation of the particles.

After precipitation, the solid mass is collected and washed. This is followed by heatingof the residue up to the boiling point of the medium to dry the resultant product and form hydroxides. The hydroxides are then calcinated to transform the hydroxide into crystalline oxides. Thakur et al. [181] used co-precipitation method to synthesize MnZn ferrite. In this method, manganese chloride, zinc chloride, iron(III) chloride and sodium hydroxide were used as raw materials. A 3M solution was prepared in 60ml of distilled water. This solution was then poured into boiling NaOH solution while stirring for 60min at temperature 353-358K with a magnetic stirrer, maintaining the pH between 11 and 12. Stirring allowed precipitates of the nanoparticles to settled down and then sample was washed many times with distilled water. After washing, the sample was dried in hot air oven followed by crushing the resultant into powder using mortar pestle. Anwar et al. [9] . These all starting materials were mixed by rapidly adding Diammonium oxalate under continuous stirring at 45 0 C for 30 min until precipitates were formed. Precipitates were washed many times and then dried in an oven at 100 0 C for 8h. Dried yellow precipitates were used to prepare ferrites by using in-house built microwave heating set up. Aluminium metal powder was used as microwave susceptor. This set up was then put on a commercial microwave oven operated at a frequency 2.45GHz. The oven was set to raise the temperature to 450 0 C. Then, brick was taken out and allowed to cool.Co-precipitation method has several advantages as it uses aqueous medium for synthesis and also the synthesis is very simple. There is a good control on the size and morphology of the nano particles formed. But this method takes long time to synthesize nanoferrites. This method is disadvantageous due to poor crystalline nature of the resultant ferrite powder.

Sol-gel method [184] is a promising method used for the preparation ofnano materials. The resultant product of this synthesis method may be either colloidal powders or films. It is a chemical solution process used to synthesize nanoparticles. A sol is a colloidal or molecular suspension of solid particles of ions in a solvent and gel is a semi-rigid mass that forms when the solvent from the sol starts evaporating where the particles left behind start to join together in a continuous network.The resultant product which comes out isin the form of colloidal powder or films. This method is advantageous because of controlled microstructure of the final product. The resultant particles formed are of uniform and small size. Also, this technique of nanoparticles synthesis is economical and it involves use of low temperature. Duan et al. [161] synthesized MnZn ferrite nanoparticles taking pure Fe(NO 3 ) 3 .9H 2 O, Zn(NO 3 ) 2 .8H 2 O and Mn(NO 3 ) 2 as starting materials. These materials were dissolved in de-ionized water at 60℃. Also, C 6 H 8 O 7 .H 2 O was dissolved in above solution to chelate the metal ions with the citrate ions and concentration was adjusted to 0.1~0.4 by adding de-ionized water. PVP was added as a binder to reduce film cracks. The spin coating was done at 3000rpm for 30s. The samples were heated at 350℃ for 30min, followed by crystallization at 550℃ for 60min after each coating. The flow chart of the sol-gel auto combustion method is shown in figure 8 . The sol-gel method is also used for depositing structurally and magnetically uniform films for spin thermoelectric generator.Gabal et al. [186] studied Mn-Zn nano-crystalline ferrites synthesized from spent Zn-C batteries using novel gelatin method. The Zn-C batteries were used to synthesize the ferrites by using sol-gel method using gelatin. Jalaiah et al. [187] synthesized nickel doped MnZn ferrites by sol-gel auto combustion method and observed non-collinear magnetic structure. The room temperature conductivity was observed to be higher than pure MnZn ferrite. There was a decrease in dielectric constant and dielectric loss tangent with increase in nickel concentration.This method is advantageous because of better size and shape control but it takes a longer time to complete the synthesis.Sol-gel method is a simple process, require low processing temperature and low cost. The prepared ferrite consists of a pure cubic spinel structure.

Combustion process is the effective and low cost method to synthesizenano materials. This process is simple, versatile and fast for nano material preparation. This method isadvantageous asless time and energyis spent during the synthesis process. The nanoparticles produced are pure and homogeneous.Many researchers synthesized MnZn ferrites by using this method [188, 189] 2 ]was used as a reducing agent in this process. Typically a solution is formedby adding these all materials in de-ionized water and heated on a hot plate at 480℃in air. Then, it ignited within 5 s with flame temperature ~1600℃.Combustion technique methodology is described in figure 5 . With doping other elements decrease in the lattice parameter was observed which could be attributed to the fact that ions of doped elements get trapped at the grain boundaries. Hence they hinder the grain growth and may cause increase in strain on the grains and lead to lattice parameter to decrease.Doping of rare-earth metals can be done using combustion method [189] in a single step. The fuel chosen in the combustion methodalso has very important effect on the MnZn ferrites prepared. The fuels that are generally preferred in this method are urea and glycine. By using these fuels uniform nanoferrites with controlled stoichiometry are obtained.

The solid-state reaction method to synthesize nanoparticles has several advantages. In this method toxic and expensive organic solvents are not used in the reaction and all the materials used to synthesize MnZn nanoparticles are easily available and cost effective. The synthesis process is performed at room temperature under atmospheric pressure which is facile and economic.Many researchers synthesized MnZn ferrites by using this method [30, 132, 134, 190] . The raw materials MnCO 3 , ZnO and Fe 2 O 3 in the proper weight were powdered and the powdered samples were calcined at 1100℃ for 5h in air atmosphere using muffle furnace with heating rate of 10℃/min and a cooling rate of 5℃/min. Then, PVA was used as a binder and powder was pettelized into small disks and torroids. Then sintering was done to get the required nano ferrites.Kogias et al. [191] studied MnZn ferrite with low losses at 500 kHz over a broad temperature range by preparing MnZn ferrite using conventional ceramic technique of solid state reaction.Tsakaloudi et al. [192] studied process and material parameters towards the design of fast firing cycles for high permeability MnZn ferrites. In this paper, high permeability of MnZn ferrites was reduced by increasingthe energy consumption in the synthesis reaction due to prolonged sintering process for the production of nanoferrites. Zapata et al. [30] studied effect of zinc concentration on the microstructure and relaxation frequency of Mn-Zn ferrites synthesized by solid state reaction. Rahaman et al. [193] studied synthesis, structural, and electromagnetic properties of Mg doped ferrites. Figure 9 shows the flow chart of various synthesis techniques.

Oxidation method is a chemical method to prepare ferrite nanoparticles. The ferrite particles synthesized are irregular, have elongated morphology. The advantage of this method is that the particles have narrow size distribution and uniform size but by using this method ferrite colloids of small size are formed. Joseyphus et al. [41] prepared MnZn ferrite by using oxidation method.The synthesis procedure of nanoparticles by oxidation method is shown in figure 10 . 3 were dissolved in 250mL water and then the mixture was allowed to react with NaOH dissolved in 250mL of water. Constant stirring was done for 2h to oxidize the metal hydroxide precipitates by adding KNO 3 .The pH was maintained between 12 and 13. Washing of the precipitates was done many times and then these were allowed to dry in an oven at 333K for 2 days.

By using this method we can synthesize MnZn ferrite at a very lower temperature. Tangsali et al. [194] synthesized Mn x Zn 1-x Fe 2 O 4 (x=0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7) by using this method. All the metal salts were mixed in proper amounts in aqueous solution of dihydrazinium nitrilotriacetate. Dry precursors of nitrilotriacetate hydrazinate of metal ions were obtained from the solution and ignited. Then the autocombustion of the dry precursors resulted in the formation of metal oxides. Tangsali et al. [195] also studied the effect of sintering conditions on the resistivity of MnZn nanoparticles prepared by using this method. The resultant products in this technique showed high saturation magnetization and high values of Curie temperature that was between 750K and 380K.

Stearic acid gel method: Stearic acid or octadecanoic acid (CH 3 (CH 2 ) 16 COOH) is a common fatty acid that exists as glycerol ester in animal and plant fat. Many researchers used stearic acid gel to synthesize nanomaterials. Jafarnejad et al. [196] used this method to synthesize MgCr 2 O 4 and Enhessari et al. [197] synthesized CoTiO 3 by using stearic acid gel method.Zhang et al. [198] synthesized MnZn ferrite with chemical formula Mn x Zn 1-x Fe 2 O 4 by using stearic acid gel method. Proper amounts of MnCO 3 , Zn(NO 3 ) 2 .6H 2 Oand Fe(NO 3 ) 2 .9H 2 O were powdered and mixed with Stearic acid in molten form. Stirring was done for 3-4h after heating the mixture in oil bath at 120℃. This resulted in formation of a brown gel. The gel was cooled in air and then powdered by grinding it. This was followed by washing of the grinded mixture with water three times followed by drying of this mixture at 100℃.MnZn ferrites were obtained by heating at 450℃ for 1 h.

The characterizations of the MnZn ferrites are done with various instruments such that X-ray diffractometer, scanning electron microscopy [199] [200] [201] , transmission electron microscopy and atomic force microscope (AFM). The magnetic properties of the ferrites are studied by vibrating sample magnetometer (VSM), magnetization hysteresis (M-H) loops [202] and electron spin resonance (ESR) hysteresis loop measurements. The X-ray investigation is done using X-ray diffractometer with CuKα radiation (λ=1.5405Å). Various formulas for the determination of lattice constant, X-ray density and crystallite size are listed below.

From the analysis of XRD data, the lattice constant can be calculated using the formula:

where a is the lattice constant, d is the interplanar spacing, and h, k, and l are the miller indices. Measurement of X-ray density (d x-ray ): Theoretical density can be calculated using the relation:

where M is the molecular mass of each component, N is the Avogadro's number (6.023×10 23 particles/mol).

Experimental density can be measured using the formula: .

where D is the crystallite size, λ=1.54056Å is the wavelength of X-ray, Ө is Bragg's angle and β is the FWHM value.

Many techniques are used to determine the shape, size and morphology of magnetic nanoparticles such as XRD, SEM, TEM, HRTEM (High resolution transmission electron microscopy) and FeSEM (Field-emission scanning electron microscopy). By using HRTEM we can get information about shape, size, crystallinity and lattice spacing. XRD is used to determine the size by using scherrer equation. However, SEM is better than XRD as XRD cannot determine the size of very small magnetic nanoparticles.

Ramiza et al. [102] studied effect of UV radiations to control particle size of Mn-Zn spinel ferrite nano-particles. From the XRD analysis it was observed that with the UV radiations minimum particle size was obtained i.e. 6.198nm . The size of the sample that was not UV treated was found to reduce from 90nm to 50nmandthe crystallite size of the pure MnZn ferrites was found to be in the range 25nm to 35nm in almost all cases as described in the table 3. The lattice parameter was found to be in the range 8.30Å to 8.570 Å. Praveena et al. [179] observed that the lattice constant lie between 8.302 Å and 8.311Å according to composition. The bulk density and the X-ray density increased from 4.98gm/cm 3 to 4.90gm/cm 3 and 5.12 gm/cm 3 to 4.98gm/cm 3 . Thakur et al. [203] studied effect of sintering temperature and observed that the average crystallite size was found to increase with increase in sintering temperature i.e. from 11.38nm to 67.42nm. Also, the lattice constant was found increasingfrom 8.409Å to 8.483Å with increasing sintering temperature. At 1373K, a well crystallized single MnZn ferrite phase was formed. Mirshekari et al. [204] observed from the XRD that the average crystallite size was in the range 43.25nm-66.7nm. Small amount of lattice strains were also observed improving its magnetic properties. Anwar et al. [9] studied the effect of sintering temperature and observed that the pure MnZn ferrite had pure spinel structure and at 673K sample had cubic spinel structure. At 923 K, the XRD pattern contained additional reflections which were due to Fe 3 O 4 . The crystallite size increased from 7 to 13nm. The lattice constant decreased from 8.439Å to 8.431Å

with an increase in sintering temperature from 673K to 923K. The XRD density was 5.21g/cm 3 and 5.23g/cm 3 as described in table 2. Gabal et al. [186] observed from the XRD analysisthat MnZn ferrites had a single phase cubic spinel structure with characteristic (311) reflection on 2Ө=34.58 and no diffraction peak due to impurity was observed. The broad diffraction peaks were observed showing ultrafine nature and small crystallite size. The lattice parameter showed a decreasing value from 8.4466Å to 8.4164Å with increasing Zn content and the density increased from 5.13g/cm 3 to 5.32g/cm 3 . Phong et al. [112] observed that the XRD pattern showed single phase spinel cubic structure with Fd3m space group. The lattice parameter was calculated 8.432Å and x-ray density was 5.27g/cm 3 . The average crystallite size was 14nm. Further from the XRD patterns [30] , it was observed that the cubic spinel phase was formed and slight contraction was observed in lattice parameter from 8.4749Å to 8.4353Å as Zn concentration increased because Zn 2+ ions (0.082nm ionic radii) replaced Mn 2+ ions (ionic radii=0.091nm). The value of sintered density increased from 4.93g/cm 3 to 4.96g/cm 3 with increase in Zn content.Jalaiah et al. [187] observed that the lattice parameter found to vary from 8.4555Å to 8.5758Å. The average crystallite size was calculated by the Scherer's formula and was found to be in the range 10nm.In the XRD pattern as observed by Angadi et al. [189] observed the Braggs reflections that indicate the crystalline nature of the samples with cubic spinel structure corresponding to Fd3m space group. When Sc 3+ concentration was increased, the peak shifted towards the lower 2Ө angle because of the relative difference between the ionic radii of Sc 3+ (0.745Å) with that of Fe 3+ (0.55Å).A decrease in the lattice parameterwas observed from8.434Å to 8.431Å on Sc 3+ doping which could be due to presence of Sc 3+ ions at the grain boundaries. In the XRD patternspeaks showed the cubic spinel structure [190] . The lattice parameter of pure MnZn ferrite increased with increase in sintering temperature from 8.3383Å to 8.3496Å and decreased in Mg doped MnZn ferrite from 8.3542Å to 8.3225Å with increasing sintering temperature. Bulk density decreased with increase in sintering temperature from 4.87g/cm 3 to 4.45 g/cm 3 in pure MnZn ferrite and from 4.61g/cm 3 to 4.57g/cm 3 in Mg doped MnZn ferrite due to discontinuous grain growth. Islam et al. [128] studied structural, magnetic and electrical properties of Gd-substituted Mn-Zn mixed ferrites. From the XRD patterns it was concluded thatfor the sample without Gd doping, the ferrite was perfectly single phase spinel and as there was anincrease in the Gd concentration, some unindexed peak as secondary phase appeared. With the increase in Gd content, the lattice parameter also increased from 8.4645Å to 8.4750Å. In the XRD patterns of Al doped MnZn ferrite observed by Haralkar [184] , the formation of cubic spinel ferrite structure was observed. It was observed that the lattice parameter decreased from 8.445Å to 8.385Å with increasing value of x due to the replacement of Fe 3+ (0.67Å) ions by Al 3+ (0.51Å). The value of X-ray density also decreased from 5.202g/cm 3 to 4.989g/cm 3 with increase in Al content. The crystallite size decreased from 19nm to 11nm with increase in Al content.From the study of Yadav et al [182] ,the XRD pattern showed spinel structure without any impurity. Also, the graphs had very broad peaks indicating the ultrafine nature and small crystallite size of ferrites. The lattice parameter increased from 8.4052Å to 8.4219Å with increase in Sm 3+ concentration.

The crystallite size decreased from 12.9nm to 8.7nm. X-ray density also increased from 5.172g/cm 3 to 6.295g/cm 3 . These all variations were because of the substitution of heavier atomic weight samarium with lower atomic weight iron.The XRD peaks studied by Kumar with Indium doping [183] showed the pure spinel phase of space group Fd3m. With the increase in Indium concentration, the XRD peaks shifted towards higher angle. This showed some lattice distortion in the cubic structure. The crystallite size increased from 14.6nm to 15.9nm with increasing doping concentration. The lattice constant increased from 8.391Å to 8.418Å. Also, the x-ray density increased from 5.315g/cm 3 to 5.445 g/cm 3 . XRD graphs of MnZn ferrite for various compositions and with Indium doping are shown in figure 11 . The characteristics peaks match with the ferrite particles and show the phase group Fd3m and spinel structure having single phase. Hence, it is concluded that the MnZn ferrites have single phase spinel cubic structure with Fd3m phase group; however some distortion in the structure can be observed because of doping.

Various techniques such as AFM, TEM, and SEM etc. are used to investigate the morphological structureof the ferrite nanoparticles. SEM is widely used for it but TEM is better than SEM because of poor resolution of SEM. AFM is a technique that can be used in different conditions like air, vacuum, liquid and moist conditions.Winiarska et al. [205] observed that the TEM gave core shell type structure formation.Mirsekari et al. [204] found from the SEM micrographs that the morphology of MnZn ferrite was porous, sponge like and agglomerated with an average particle size of 2µm. Anwar et al. [9] observed from the SEM micrographs that the particles were spherical in shape.Gabal et al. [206] studies showed that TEM morphology showed very strong agglomeration of the cubic particles, having some particles in one line. From the SEM micrographs [192] , mean grain diameter was observed 7.88±0.4µm.In Phong observation [112] the TEM images showed that the ferrites had homogeneous structure and spherical in shape. Particles showed agglomeration due to slow particle growth.In the SEM analysis of the Ni doped ferrite done by Jalaiah [187] , the presence of aggregates of small grains at the surface of the higher nickel containing samples was observed. In the TEM analysis done by Angadi et al. [189] the particles were lightly agglomerated due to their slow growth of particles during the preparation. The particle size of pure Mn 0.5 Zn 0.5 Fe 2 O 4 was about 20nm. The TEM images showed that the electron diffraction pattern consisted of concentric rings with spots over the rings showing that the samples were crystalline in nature. The particle size lies between 20 and 23nm. From the SEM images [190] , it was concluded that polyhedral morphology with nonuniform grains were displayed for both pure and doped MnZnferrites. Pure MnZn ferrites sintered at 1150℃ had average grain size of 2.10µm having well defined grain boundaries and the sample sintered at 1200℃ and 1250℃ had grain size of 2.84μm and 3.13µm. In case of Mg doped ferrites, grain size increased with sintering temperature from 2.00 to 3.10µm. From the TEM images [84] , it was concluded that the molecules were spherical in shape and particles were aggregated. From the SEM analysis by Yadav et al. [182] , it was observed that particle size increased with Sm content but bigger particles were formed by the agglomeration of ultra fine particles. The TEM images showed that all the particles were nearly spherical in shape and average particle size was 10-20nm. SEM analysis [183] showed the uniform, spherical shaped and loosely agglomerated particles. The shape of the MnZn ferrites is usually spherical and having particle size in the 9-23nm range. The SEM images of the pure MnZn ferrites are shown in figure 12 that shows spherical structure of the ferrite nanoparticles and in figure 13 SEM images shows elongated nature of the ferrite nanoparticles. Also, the TEM images of pure MnZn ferrite nanoparticles are shown in figure 14.

FT-IR stands for Fourier transform Infrared, the method that is used for infrared spectroscopy. In infrared spectroscopy, IR radiation is passed through a sample. Some of the infrared radiation is absorbed by the sample and some is passed through or transmitted. The resulting spectrum represents the molecular absorption and transmission, creating a molecular fingerprint of the sample. Islam et al. [128] recorded the FTIR spectra of MnZn ferrite nanoparticles in the range from 250cm -1 to 4000cm -1 .In the FTIR spectra [184] , the value of the absorption band ⱱ 1 around 600cm -1 remained almost constant whereas the value of absorption spectra ⱱ 2 around 400cm -1 decreased from 548cm -1 to 528cm -1 . This is because of the difference in Fe 3+ -O 2distance for tetrahedral and octahedral sites. The absorption bands in the region 1200cm -1 -1500cm -1 correspond to NO 3 ions, absorption band at 1700cm -1 showed carboxyl group COOand at 2300cm -1 correspond to hydrogen bonded O-H groups.In the FTIR spectra [189] , two prominent absorption bands nearly at 540cm -1 (ⱱ 1 ) and 360cm -1 (ⱱ 2 ) observed were attributed to the tetrahedral and the octahedral complexes. The difference between these two values was due to the relative changes in bond length (Fe-O) at tetrahedral (A) sites and octahedral (B) sites.The FTIR spectra recorded by Gabal [206] in the range 600cm -1 -200cm -1 showed high frequency band (ⱱ 1 ) increased with increasing Zn content due to vibrational spectra of metal ion-oxygen complex in the tetrahedral sites, while value of lower frequency band (ⱱ 2 ) due to vibration in the octahedral site, slightly changed. FTIR of all compounds showed the formation of spinel phase.Ciocarlan et al. [103] synthesized Mn ferrite along with Ni ferrite, Zn ferrite and Co ferrite and studied their various properties. Formation of spinel phase is observed from FT-IR spectra of all the compounds as shown in figure 17 (b).

MnZn ferrites are the magnetic materials with very low power loss so that they can be used n many electronic applications. Aiping 2006 et al. [123] synthesized MnZn ferrites using conventional ceramic processing technique and studied the effect of SnO 2 addition the magnetic properties of the prepared ferrite. It was observed that there is overall decrease in the loss factor with increase in SnO 2 concentration. Also, power loss and minimum power loss decreased with increase in the doping of SnO 2 as shown in figure 16 (c).Jalaiah et al. [187] . The core losses measured at 100 kHz and 200mT showed that the core losses for all samples decreased firstly and then increased with increasing temperature further. The power loss for unsubstituted and Ti 4+ sample was higher at room temperature. Also, temperature of minimum in P L~T curve shifts to lower temperature for Ti 4+ and Sn 4+ substituted samples. At low frequencies the there was power losses only due to eddy current loss P e and hysteresis loss P h . The P h decreased with increasing temperature firstly up to 80 0 C and then increased with further increase in temperature and it was minimum for Sn 4+ doping. The P e of all samples were relatively low and there was a slight change at low temperature but there was a sharp increase at high temperature as shown in figure 16 (a), (b) as the starting materials. The power loss vs. temperature plot showed that the power loss decreased firstly and then increased with an increase in temperature showing lowest loss point between 60°C and 100°C. Power loss reduced as the concentration of additives was increased. Also, both the hysteresis loss and the eddy current loss decreased with increase in concentration of additives and after reaching minima for concentration of TiO 2 and Nb 2 O 5 , 0.03 wt% and 0.02 wt% increased further. This is because as small amount of Ti 4+ and Nb 5+ ions were entered into the grains cause an increase in Fe 2+ ions , which lead to positive K 1 values and decrease the hysteresis loss. Further increasing the dopant concentration cause excessive increase in Fe 2+ ions, which make K 1 value more positive and increase the hysteresis loss. When the concentration of TiO 2 and Nb 2 O 5 was less than 0.03wt% and 0.02 wt%, the grain and grain boundary resistivity both increased and hence, the eddy current loss decreased as eddy current loss is inversely proportional to resistivity. Further increase in additives concentration decreased the resistivity, causing the eddy current loss to increase. Anwar et al. [9] studied the effect of sintering temperature on various structural, electrical and dielectric parameters of MnZn ferrites using the co-precipitation method for the synthesis of Mn 0.5 Zn 0.5 Fe 2 O 4 . The dielectric constant decreased very sharply in low frequency region and slowed down in high frequency region almost approached to frequency independent nature. It exhibit dielectric dispersion. From the plot of loss tangent vs. frequency it was observed that the loss tangent decreased initially with increase in frequency and then showed a relaxation peak. It is observed from all this data that MnZnnanoferrites have very low power loss to be used suitably in making various electronic appliances.

Most common techniques for determining the magnetic properties of ferrite nanoparticles are VSM (vibrating sample magnetometer), magnetization hysteresis (M-H) loops and electron spin resonance (ESR) hysteresis loop measurements. We can calculate saturation magnetization, remenant magnetization and coercivity by using these characterization techniques.

Saturation magnetization is the saturation value of magnetization of a ferromagnetic body. The inside of the magnetic body is normally divided into many number of domains, but as the external magnetic field increases, domain walls may move and magnetization may rotate within domains, so the magnetic body comes in single-domain state. The magnetization saturation is reached if the easy magnetization axis and the external magnetic field direction match and the value of the magnetization at this time is called the saturation magnetization. The value of this saturation magnetization of MnZn ferrites is high [141, 162] in comparison to other ferrites. Syue et al. [188] observedthe value of saturation magnetization increased from 11-62emu/g with increasing Mn 2+ content and saturates further.The value of saturation magnetization remained in the range 11.090emu/g to 60.868emu/g [188] when combustion method is used without subsequent heat treatments. Praveena et al. [179] observed that the value of saturation magnetization (M s ) increased from 53.33Am 2 /Kg to 78.26Am 2 /Kg with increase in zinc content and then decreased to 10.74Am 2 /kg if zinc content is further increased. From the hysteresis curves Mirsekari et al. [204] observed that the saturation magnetization decreased from 69 to 34 emu/g.Gabal et al. [186] observed the value saturation magnetization M s increased from 32.9emu/g to 37.6emu/g,then decreasedto 25.9emu/g and again increased to 43.7emu/g.The value of saturation magnetization was found to be 27.7emu/g in Phong [112] experiment showed the properties of superspin glass and supermagnetismbehavior.The study of Zapata [30] showed that the M s value decreased from 36.22emu/g to 30.78emu/g with increase in Zn concentration. This was due to the fact that increased Zn content decreased the ferric ions on the A sites and this reduced the A-B interaction. The saturation magnetization (M s ) [187] decreased firstly from 120.896emu/gm to 114.888emu/gm with increase in Ni concentration and then increased to 137.246emu/gm with further increase in Ni concentration as shown in figure 13 . This decrease was due to the occupation of Ni 2+ ions in octahedral B sites.Angadi et al. [171] observed thatFrom the M-H loops recorded by VSM the variation of saturation magnetization(M s ) increased with increasing Sc 3+ doping from 24.6emu/g to 31.48emu/g and then decreased further to 23.45emu/g. Hence, the Sc 3+ doped Mn-Zn ferrites are useful for modern technological applications as well as low and high frequency applications. Islam et al. [128] observed that the value of saturation magnetization decreased from 51.2emu/gm to 40.3emu/gm with an increase in Gd content. By doping Al in pure MnZn ferrite [184] the saturation magnetization decreased with increase in Al content.Hysteresis loops measurements by Yadav et al. [182] showed that the value of saturation magnetization increased from 23.95emu/gm to 42.10emu/gm.Due to this, high value of magnetization MnZn ferrites are used in the field of power applications.

Remanent magnetization is the value of magnetization that remains in the absence of an induced magnetic field. Mirshekari et al. [204] studied structural and magnetic properties of Mn-Zn ferrite. From the hysteresis curves, it was observed that remenantmagnetization decreased from 21.25emu/g to 8 emu/g.Syue et al. [188] studied magnetic properties of MnZn ferrites and found that the value of remenant magnetization remained in the range 0.769 emu/g to 8.451emu/g and it was observed that it was lowest for pure zinc ferrite and highest for pure manganese ferrite.Praveena [179] studied magnetic properties of MnZn ferrite and found that remenant magnetization showed increase in value from 21.70Am 2 /kg to 29.58Am 2 /kg and then decreased to 4.36Am 2 /kg with increasing x value as described in table 2.Gabal et al. [186] showed that the remenant magnetization also increased from 5.5emu/g to 6.7emu/g firstly and then decreased to 3.6emu/g and again increased to 7.3emu/g. After doping Al [184] [84] the remanence magnetization M r varied from 0.5emu/g to 1.32emu/g with Al content.Yadav et al. [182] observed that remanence magnetization increased from 0emu/g to 8.50emu/gm with increasing value of Sm content from 0.0 to 0.5. Figure 15 shows the results of VSM characterization of MnZn ferrite having high value of saturation magnetization and low coercivity.

The coercivity is also called as coercive field and coercive force. It is defined as the ability of a ferromagnetic material to withstand an external magnetic field without demagnetizing it. In case of a ferromagnetic material, it is defined as the intensity of applied magnetic field that is required to reduce the magnetization to zero after the saturation state of the magnetization. The materials which have high coercivity are called hard materials and the materials with low value of coercivity are soft materials. The hard materials are used to make the permanent magnets and soft materials are used for making transformers, inductor cores and microwave devices. Praveena et al. [179] found the coercivity value varying in the range 0.0149Oe-0.0172Oe for Mn 1-x Zn x Fe 2 O 4 (x=0.0-1.0). From the hysteresis curves Mirsekari et al. [204] observed that the coercivity decreased from 60Oe to 45Oe with increasing x from 0.2 to 0.8. The coercivity as calculated by Gabal [186] showed decreasing trend. It decreased from 94.2Oe to 67.1Oe for x=0.2-0.6 and then increased to 80.7Oe for x=0.8.Phong et al. [112] studied the properties of MnZn ferrites and found that the coercivity was 130Oe at 10K.Jalaiah et al. [187] observed from his experiment that the coercivity values of the Mn 0.85 Zn 0.15 Ni x Fe 2 O 4 (x=0.03, 0.06, 0.09, 0.12 and 0.15) samples increased with nickel concentration from 0.123Oe to 0.24Oe because of the decrease in the porosity with increasing dopant concentration. Also, the coercivity decreased from 87Oe to 11Oe with increasing Al 3+ concentration [184] .The low value of coercivity of MnZn ferrite put these ferrites in the class of soft ferrites and these are used in applications like making transformer cores, microwave devices and inductors.

Due to useful magnetic, electrical and optical properties of ferrite nanoparticles, researchers are taking interest in the synthesis of ferrite nanoparticles and making their use in a lot of applications that include medical field, information technology, antenna, microwave absorbing materials, biosensors and many electronic applications [207] [208] [209] [210] [211] [212] [213] [214] [215] [216] . Many reviews are there about the synthesis, properties and applications of ferrites in biomedical [217] [218] [219] , catalyst [220, 221] and wastewater treatment [200, [222] [223] [224] [225] . MnZn ferrites have a broad area of applications due to high saturation magnetization [226] , high initial permeability [50, 227] , low power loss [228] . The application area of MnZn ferrites include power applications [229] [230] [231] [232] [233] [234] [235] , microwave devices [236] , magnetic fluid [145, 237] , radar absorbing system, high frequency applications [238, 239] , bio-medical [240] , water purification [241, 242] etc.Use of MnZn ferrites in the field of power application attracted great attention in the research areas. From last many years the MnZn ferrites are synthesized to be used in power applications for making current convertors [227] , power inductors with magnetic cores [130] , electronic transformer cores [243] , high frequency applications [143] ,electronics and communication [244] .

Ferrite nanoparticles have low electrical conductivity and low dielectric losses [245] , so they can be used in microwave devices. MnZn ferrites are most suitable for their use in the microwave devices because of high permittivity, high resistivity, high stability, high value of saturation magnetization, high curie temperature with low eddy current and low magnetic losses [246, 247] . Due to the use of ferrite nanomaterials, electronic devices can be mechanically hard, chemically stable and permit the materials to operate properly at a wide frequency range [248] . There are a lot of advantages of the use of MnZn ferrites in the microwave devices. There is a decrease in the emission of unwanted EM waves from the device and also it absorbs the incoming EM waves that may harm the microwave device. MnZn ferrites are used in microwave systems because of their low loss and high saturation magnetization. Wang et al. [249] synthesized MnZn ferrite nanoparticles and the result showed that because of high reflection loss and broad absorbing band in low frequency (10MHz to 1GHz) these ferrites can be used in electromagnetic microwave absorbing field.

The radiations emitting from radar results in the increase in electromagnetic radiation pollution in the environment. These radiations reduce the efficiency and performance of electronic instruments and thus decrease their lifetime and safety. As MnZn ferrite belongs to the class of soft ferrites having high electrochemical stability, high permeability, high saturation magnetization and low power losses, it is used in many electronic applications [65, 79, 128, 167, 199, 209, 210] .Ferrite nanoparticles can be used in the radar absorbing devices due to their high value of curie temperature and temperature stability. Also the ferrite nanoparticles are environmentally safe that make their use easier in the radar absorbing devices. The application of MnZn ferrites in radar absorbing system is also attracting the researchers. Praveena et al. [252] synthesized Ni 0.4 Zn 0.2 Mn 0.4 Fe 2 O 4 nano ferrites for radar absorbing. The high value of Curie temperature indicated homogeneity and temperature stability. The EPR spectra showed reduction in the peak width and increase in relaxation with increase in sintering temperature. These all results showed that the ferrite nanoparticles can be used for radar absorbing from few MHz to 2 GHz and also these materials are environmentally safe. By carefully controlling Zn 2+ doping level, nanoparticles of size 15 nm with single crystallinity and size monodispersity (s<5%) and having high magnetization value (175 emu g -1 ) were obtained. The nanoparticles provided the large MRI contrast effects (r2 = 860 mm -1 s -1 ) with an eight to fourteen fold increase in MRI contrast and a fourfold enhancement in hyperthermic effects compared to conventional iron oxide nanoparticles. This enhancement was significant for clinical purposes as the nanoparticle probe dosage level can be progressively lowered when using probes that have improved contrast enhancement effects. For (Zn x Mn 1-x )Fe 2 O 4 nanoparticles, Zn 2+ ions mainly occupy tetrahedral sites of the spinel matrix which was confirmed by using extended X-ray absorption fine structure (EXAFS) analysis to examine the Zn and Fe K-edges. To detect small sized pathogenic targets precisely at an early stage, MRI contrast agents are often used to highlight those specific areas of interest. Due to high imaging contrast effects, magnetic nanoparticles can increase the difference between pathogenic targets and normal tissues via MRI. One of the most appropriate ways to increase the MR contrast effects is the optimization of saturation magnetization (Ms) that is directly related to the relaxivity coefficient (r2). The relaxivity coefficient (r2) is determined by a slope of R2 against nanoparticle concentration and often used as an indicator for contrast effects. The relaxivity coefficient (r2) of contrast agents can be tuned and further enhanced by engineering magnetic parameters [253] .

MnZn ferrite nanoparticles are used in making many electronic devices due to their enhanced electrical properties such as high value of resistivity, low ac conductivity, low power losses etc. Dobak et al. [105] studied miniaturization of components due to low loss MnZn ferrites. Also, Sun et al. [138] studied effect of ZrO 2 addition on the microstructure and various properties of MnZn ferrites and found that the optimal values of initial permeability (2322), saturation magnetization (522mT) and power loss (386kW/m 3 ) make it suitable for switch mode power supply applications.Due to suitable electrical and magnetic properties of the Sc 3+ doped Mn-Zn ferrites, these were useful for modern technological application as well as for low and high frequency application.MnZn ferrites are also used to construct power inductors [254, 255] , wireless power transfer applications [256] and for making inductive components [39] .

One of the major use of MnZn ferrites is in telecommunication and high frequency applications [180] . MnZn ferrites have applications in field of bio-medical and hyperthermia [112] . Hurtado et al. [257] synthesized MnZn ferrite along with activated carbon composite for use in bio-medical applications. MnZn ferrites can be used to make ferrofluid [182] due to high value of saturation magnetization. Arulmurugan et al. [76] synthesized Co-Zn and Mn-Zn ferrite nanoparticles and found that because of low curie temperature and high value of thermomagnetic coefficient, these ferrites can be used for preparing temperature sensitive ferrofluid.Praveena et al. [258] synthesized Mn-Zn ferrite nanoparticles for high frequency applications. The ferrites had low power loss in frequency range 10Hz-1MHz. The constructed transformer with the ferrite material showed high efficiency and low surface temperature rise at frequency 1 MHz making it suitable for operating at high frequencies. 7.6.MnZn for onging COVID-19 pandemics: As nanomaterials are making a global impact on healthcare and socioeconomic development so are the viruses during pandemics. Nanoparticles of MnZn have unique physical and chemical properties that have associated benefits in development of potential therapeutic drugs, nanomaterial based environment friendly antiviral sprays, drug delivery and to develop anti-viral surface coatings in home appliances. This is attributed to the fact that the choice of synthesis method provides size and chargetunability properties to the MnZn. The size tunablity ensures that large amount of drug can be delivered into anatomically privileged sites of the virus while charge tunability would facilitate entry of drug in to charged parts of the virus [260] . In addition, biosensors for the early detection of viral strains such the COVID 19 can also be developed withMnZn. For instance MnZn can readily be used to before Gaint magnetoresistance sensors which have previously been used for virus detection [261] .

The synthesis of MnZn particles has increased in last ten years and most progress can be seen in the year 2016. Due to the fascinating properties of MnZn ferrites among the class of soft ferrites like high value of saturation magnetization, low value of coercivity, high initial permeability, narrow size distribution of the ferrite particles, low remenant magnetization, the researchers are taking interest in the synthesis of these ferrites.The co-precipitation and sol-gel method is best for getting the fine crystallite size among all synthesis techniques. The XRD pattern of the MnZn ferrites has characteristic peaks showing the cubic spinel phase having Fd3m phase group. The shape of the prepared ferrite is nearly spherical but some distortion may be observed after doping. FTIR spectra confirmed the spinel phase of the ferrite nanoparticles having tetrahedral and octahedral sites.The value of saturation magnetization is highest when we synthesize the MnZn ferrites with proper amount of nickel doping by using sol-gel auto combustion method. Also, for getting the low value of coercivity sol-gel method is preferred. Generally, MnZn ferrites have a lot of applications including biomedical field, electronic devices, for making radar absorbing materials, for making ferrofluids etc. For more enhancing the applications and advantageous properties of MnZn ferrite nanoparticles, further studies are required.The electrical and magnetic properties of MnZn ferrites can be enhanced by doping other metals such as cobalt, zinc, magnesium to make them suitable for use in agricultural and electrical applications. In the context of use of nanoparticles in thepandemic outbreak, such as in the recent COVID-19,MnZn soft ferrites can play a significant role in the development of high contrast imaging dyes for viral strains in body fluids. Perhaps MnZn can also serve as a candidate nanomaterial for developing nanomaterial based medicines and therapeutics. Table 1 : Summary of advantages and disadvantages of major synthesis techniques 

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Maximizing Specific Loss Power for Magnetic Hyperthermia by Hard-Soft Mixed Ferrites

Microstructure and Temperature Dependence of Magnetic Properties of MnZnTiSn Ferrites for Power Applications

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Core-shell hybrid nanomaterials based on CoFe2O4 particles coated with PVP or PEG biopolymers for applications in biomedicine

Spin valves using insulating cobalt ferrite exchange-spring pinning layers

Application of Mechanochemistry in Ferrite Materials Technology

Effect of zinc concentration on the microstructure and relaxation frequency of Mn-Zn ferrites synthesized by solid state reaction

Domain wall dispersions: Relaxation and resonance in Ni-Zn ferrite doped with V2 O3

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Functionalization of Cobalt Ferrite Nanoparticles with Alginate Coating for Biocompatible Applications

Energy Losses in Soft Magnetic Materials under Symmetric and Asymmetric Induction Waveforms

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Effect of annealing atmosphere on phase formation and electrical characteristics of bismuth ferrite thin films

Microwave applications of soft ferrites

Soft ferrite materials for multilayer inductors

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Structure and magnetic properties of rf thermally plasma synthesized Mn and Mn-Zn ferrite nanoparticles

Plasma-sprayed MnZn ferrites with insulated fine grains and increased resistivity for high-frequency applications

New MnZn Ferrites with High Saturation Flux Density

Doping effect of Y 3 ions on the microstructural and electromagnetic properties of MnZn ferrites

Combined effect of demagnetizing field and induced magnetic anisotropy on the magnetic properties of manganesezinc ferrite composites

Modification of dielectric and mechanical properties of rubber ferrite composites containing manganese zinc ferrite

Use of multiple-edge refinement of extended x-ray absorption fine structure to determine site occupancy in mixed ferrite nanoparticles

Xray absorption, neutron diffraction, and Mössbauer effect studies of MnZn-ferrite processed through high-energy ball milling

Study of dielectric behaviour of Mn -Zn nano ferrites

Low temperature processing of Mn-Zn nanoferrites

Magnetic properties of selected substituted spinel ferrites

Magnetic and dielectric properties of Mn0.2Ni 0.8Fe2O4 nanoparticles synthesized by PEG-assisted hydrothermal method

Excess of cations in the sol-gel synthesis of cobalt ferrite (CoFe 2 O 4 ): A pathway to switching the inversion degree of spinels

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Fabrication and microwave absorbing properties of Ni-Zn spinel ferrites

Effects of calcining and sintering parameters on the magnetic properties of high-permeability MnZn ferrites

Complex permeability and permittivity spectra of polycrystalline Ni-Zn ferrite samples with different microstructures

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Frequency dispersion of complex permeability in Mn-Zn and Ni-Zn spinel ferrites and their composite materials

Structural, electrical and magnetic parameters evaluation of nanocrystalline rare earth Nd 3+ -substituted nickel-zinc spinel ferrite particles

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Magnetic properties of MnZn ferrites prepared by soft chemical routes

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Synthesis of nanocrystalline Ni-Zn ferrites by combustion method with no postannealing route

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Effect of nanoparticles on the magnetic properties of Mn-Zn soft ferrite

Co-precipitation method of synthesis and characterization of iron oxide nanoparticles

Direct Preparation of the Nanocrystalline MnZn Ferrites by Using Oxalate as Precipitant

Polycrystalline MnZn ferrite films prepared by pulsed laser deposition

Frequency dependence of electrical and magnetic properties of Li-Ni-Mn-Co ferrites

Studies of the Magnetic Properties and Specific Absorption of Mn0.3Zn0.7Fe2O4 Nanoparticles

Hydrothermal Synthesis of Manganese Zinc Ferrite Powders from Oxides

Evolution of the MnZn-ferrite microstructure by applying of a thin liquid-phase film

Ferrite By Citrate Precursor Method

Preparation and Characterization of Low and High Frequency Applications by Citrate Precursor Method

A study of nanostructured Zn -Mn soft spinel ferrites by the citrate precursor method

Temperature stable MnZn ferrites for applications in the frequency region of 500 kHz

Magnetic and structural studies of the Mn-doped Mg-Zn ferrite nanoparticles synthesized by the glycine nitrate process

Preparation of MnZn-ferrite with microemulsion technique

Structure of Spinel

Influence of Sintering on the Structural, Electrical, and Magnetic Properties of Li-Ni-Mn-Zn Ferrite Synthesized by Citrate Precursor Method

Effects of SnO2 addition on the magnetic properties of manganese zinc ferrites

Concurrent core loss suppression and high permeability by introduction of highly insulating intergranular magnetic inclusions to MnZn ferrite

Cation distribution and magnetic property of Ti/Sn-substituted manganese-zinc ferrites

Engineering High Permeability: Mn-Zn and Ni-Zn Ferrites

High permeability-high frequency stable MnZn ferrites

Study of the structural, magnetic and electrical properties of Gd-substituted Mn-Zn mixed ferrites

Effect of TiO2and Nb2O5additives on the magnetic properties of cobalt-modified MnZn ferrites

A novel silicon-embedded toroidal power inductor with magnetic core

Temperature dependence of core loss in Co-substituted MnZn ferrites

Effects of Nb2O5, TiO2, SiO2, and CaO additions on the loss characteristics of Mn-Zn Ferrite

The influence of remanence on magnetostrictive vibration and hysteresis in Mn-Zn ferrite cores

Process and material parameters towards the design of fast firing cycles for high permeability MnZn ferrites

Complex additive systems for Mn-Zn ferrites with low power loss

Hysteresis losses of minor loops versus temperature in MnZn ferrite

Estimation of Eddy-Current Loss for MnZn Ferrite Cores

Effects of nano-TiO2 and normal size TiO2 additions on the microstructure and magnetic properties of manganese-zinc power ferrites

Effect of MoO3Addition on the Magnetic Properties and Complex Impedance of Mn-Zn Ferrites with High Bsand High Initial Permeability

Soft magnetic properties of MnZn ferrites prepared by powder injection moulding

Ternary monodispersed Mn0.5Zn0.5Fe2O 4 ferrite nanoparticles: Preparation and magnetic characterization

Development of a new soft ferrite core for power applications

Effects of MnZn ferrite doping on magnetic and electrical properties of NiZnCu ferrite toroid cores for power applications

Synthesis of a low loss Mn-Zn ferrite for power applications

Performance of Mn-Zn ferrite magnetic fluid in a prototype distribution transformer under varying loading conditions

Synthesis and characterization of carboxymethyl dextran-coated Mn/Zn ferrite for biomedical applications

Mn-Zn spinel ferrite thin films prepared by high rate reactive facing targets sputtering

Mn-Zn ferrite nanoparticles coated with mesoporous silica as core material for heat-triggered release of therapeutic agents

Effect of Zinc Concentration on the Structural , Optical , and Magnetic Properties of Mixed Co-Zn Ferrites Nanoparticles Synthesized by Low-Temperature Hydrothermal Method

Preparation of cobalt substituted zinc ferrite nanopowders via auto-combustion route : an investigation to their structural and magnetic properties

Synthesis and Characterization of Metal (Mn,Zn) Ferrite Magnetic Nanoparticles

Synthesis and the physical properties of MnZn ferrite and NiMnZn ferrite-polyaniline nanocomposite particles

Magnetic properties and loss separation in FeSi/MnZnFe2O4soft magnetic composites

Microwave assisted low temperature synthesis of MnZn ferrite nanoparticles

Deposition of nanoscale films on the nanopore-arrayed template by an in-situ spinning-precipitated technique, Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry

Molten-salt synthesis of flaky MnZn-ferrite powder for electromagnetic shielding applications

Synthesis of MnZn-Ferrite Using Sintering Aids

Tuning the structural and magnetic properties of MnZn nano-ferrites synthesized under a high magnetic field

Journal of Magnetism and Magnetic Materials Tuning magnetic and structural properties of MnFe 2 O 4 nanostructures by systematic introduction of transition metal ions M 2 + ( M = Zn

Characterization of as-deposited and sintered Mn0.5Zn0.5Fe2O4 films formed by sol-gel

Oriented attachment of ultra-small Mn(1-x)ZnxFe2O4 nanoparticles during the non-aqueous sol-gel synthesis

Enhanced soft magnetic properties of iron powders through coating MnZn ferrite by one-step sol-gel synthesis

Journal of Magnetism and Magnetic Materials Structural , dielectric and magnetic properties of Mn + 2 doped cobalt ferrite nanoparticles

Nanocrystalline magnetite and Mn-Zn ferrite particles via the polyol process: Synthesis and magnetic properties

Processing of High Density Manganese Zinc Nanoferrites by Co-Precipitation Method

Effects of Co-substitution on wide temperature ranging characteristic of electromagnetic properties in MnZn ferrites

Densification, magnetic and dielectric behaviour of Cu-substituted Mg-Zn ferrites

Effect of Sm3+-Gd3+ on structural, electrical and magnetic properties of Mn-Zn ferrites synthesized via combustion route

The effect of Nb2O5 dopant on the structural and magnetic properties of MnZnferrites

Effects of Ce3+ doping on the structure and magnetic properties of Mn-Zn ferrite fibers

Hydrothermal Synthesis of Manganese Zinc Ferrites

Microwave processing of ceramics, Current Opinion in Solid State and Materials Science

Journal of Magnetism and Magnetic Materials Synthesis , optical and magnetic properties of pure and Co-doped ZnFe 2 O 4 nanoparticles by microwave combustion method

Superlattices and Microstructures Optical and magnetic properties of Mgdoped ZnFe 2 O 4 nanoparticles prepared by rapid microwave combustion method q

Conventional and Microwave Hydrothermal Synthesis and Application of Functional Materials: A Review

Structural and Magnetic Properties of Mn-Zn Ferrites Synthesized by Microwave-Hydrothermal Process , Solid State Phenomena

Structural, morphological, magnetic and optical study of co-precipitated Nd 3+ doped Mn-Zn ferrite nanoparticles

Finite size effect on Sm 3+ doped Mn<inf>0.5</inf>Zn<inf>0.5</inf>Sm<inf>x</inf>Fe<inf>2-x</inf>O<inf>4</inf> (0≤x≤0.5) ferrite nanoparticles

Study of conduction phenomena in indium substituted Mn-Zn nanoferrites

Intrinsic magnetic, structural and resistivity properties of ferromagnetic Mn 0.5 Zn 0.5 Al x Fe 2-x O 4 nanoparticles

Effects of sol concentration on the structure and magnetic properties of sol-gel MnZn ferrites

Mn-Zn nano-crystalline ferrites synthesized from spent Zn-C batteries using novel gelatin method

Structural, magnetic and electrical properties of nickel doped Mn-Zn spinel ferrite synthesized by sol-gel method

Magnetic and electrical properties of Mn-Zn ferrites synthesized by combustion method without subsequent heat treatments

Structural, electrical and magnetic properties of Sc3+ doped Mn-Zn ferrite nanoparticles

Akther Hossain, Synthesis, structural, and electromagnetic properties of Mn0

New MnZn Ferrite with Low Losses at 500 kHz over a Broad Temperature Range

On the Question of Thermal Stability and Magnetic Properties of Mn 0.6 Zn 0.4 Fe 2 O 4 Nanoparticles Prepared by Sol-Gel Method

Akther Hossain, Study the effect of sintering temperature on structural, microstructural and electromagnetic properties of 10% Ca-doped Mn0.6Zn0.4Fe2O4

Effect of sintering conditions on resistivity of nanoparticle Mn-Zn ferrite prepared by nitrilotriacetate precursor method

Synthesis, characterization and optical band gap of Pirochromite (MgCr2O4) Nanoparticles by Stearic Acid Sol-Gel Method

Magnetic properties and heat capacity of cotio 3 nanopowders prepared by stearic acid gel method

Synthesis and characterization of titania-coated Mn-Zn ferrite nanoparticles

An analysis of Mn-Zn ferrite microstructure by impedance spectroscopy, scanning transmission electron microscopy and energy dispersion spectrometry characterizations

Magnetic nanoparticles: Synthesis, protection, functionalization, and application

Structure and magnetic properties of manganese-zinc-ferrites prepared by spray pyrolysis method

Model of the Magnetostrictive Hysteresis Loop with Local Maximum

Structural and optical properties of Mn0.5Zn0.5Fe2O4 nano ferrites: Effect of sintering temperature

Structure and Magnetic Properties of Mn-Zn Ferrite Synthesized by Glycine-Nitrate Auto-Combustion Process

Study of the Catalytic Activity and Surface Properties of Manganese-Zinc Ferrite Prepared from Used Batteries

Influence of Alsubstitution on structural, electrical and magnetic properties of Mn-Zn ferrites nanopowders prepared via the sol-gel auto-combustion method

Novel Applications of Ferrites

Recent Advances in Nanoporous Membranes for Water Purification

Ferrites : magnetic materials as an alternate source of green electrical energy

Effect of Gd 3 þ -, Pr 3 þ -or Sm 3 þsubstituted cobalt e zinc ferrite on photodegradation of methyl orange and cytotoxicity tests

RSC Advances fundamental and redox catalytic properties for the

Photocatalysis of cobalt zinc ferrite nanorods under solar light

Application of spinel ferrite nanoparticles in water and wastewater treatment: A review, Separation and Purification Technology

Visible-Light-Induced Photocatalyst Based on Cobalt-Doped Zinc Ferrite Nanocrystals

Degradation of Methyl Red under Visible Light Using N , F-TiO 2 / SiO 2 / rGO Nanocomposite

ScienceDirect ICNANO 2016 Morphology , Impedance and Photocatalytic studies, Materials Today: Proceedings. 4 (2017)

Recent Developments in Magnetic Diagnostic Systems

Iron Oxide Based Nanoparticles for Multimodal Imaging and Magnetoresponsive Therapy

Chemical Synthesis and Assembly of Uniformly Sized Iron Oxide Nanoparticles for Medical Applications

Silica-decorated magnetic nanocomposites for catalytic applications

Combustion synthesis and nanomaterials, Current Opinion in Solid State and Materials Science

Synthesis, characterization, applications, and challenges of iron oxide nanoparticles

Ac ce pt

Removal of arsenic from water using nano adsorbents and challenges : A review

FMR and Magnetic Studies of RF-Sputtered Mn-Zn Ferrite Thin Films

Low loss MnZn ferrites for applications in the frequency region of 1-3 MHz

Eddy-current losses in Mn-Zn ferrites

A Procedure for the Extraction of Intrinsic AC Conductivity and Dielectric Constant of N87 Mn-Zn Ferrite Samples Based on Impedance Measurements and Equivalent Electrical Circuit Modeling

of Mn -Zn Ferrite Cores

Mn-Zn ferrite round cable EMI suppressor with deep grooves and a secondary short circuit for different frequency ranges

Novel Tests for the As-Manufactured Strength of Mn-Zn Ferrite Inductor Cores

Electric field breakdown in Wireless Power Transfer systems due to ferrite dielectric polarizability

Magnetic Field Energy Harvesting under Overhead Power Lines

High resistive ferrite films by a solution process for electromagnetic compatible (EMC) devices

Microwave firing of MnZn-ferrites

Mn-Zn ferrite with higher magnetization for temperature sensitive magnetic fluid

Super paramagnetic la doped Mn-Zn nano ferrites: Dependence on dopant content and crystallite size

Structural, morphological, magnetic and dielectric characterization of nanophased antimony doped manganese zinc ferrites

Magnetic properties of samarium and gadolinium co-doping Mn-Zn ferrites obtained by sol-gel auto-combustion method

Spinel ferrite magnetic adsorbents: Alternative future materials for water purification?

Magnetically Separable MnFe 2 O 4 / TA / ZnO Nanocomposites for Photocatalytic Degradation of Congo Red Under Visible Light

Effect of firing temperature on the electromagnetic properties of electronic transformer cores developed by using nanosized Mn-Zn ferrite powders

Heterotube Mn-Zn Ferrite Bundle EMI Suppressor with Different Magnetic Coupling Configurations

Author ' s Accepted Manuscript

Nickel -zinc ferrite fabricated by sol -gel route and application in hightemperature superconducting magnetic energy storage for voltage sag solving

as a potential candidate for microwave device applications

Structural , Magnetic and Microwave Properties of Eu-doped Barium Hexaferrite Powders

Synthesis, structure and electromagnetic properties of Mn-Zn ferrite by sol-gel combustion technique

Magnetic and Magnetocaloric Properties of Zn 1 À x Co x Fe 2 O 4 Nanoparticles

Effect of sintering temperature on the structural, dielectric and magnetic properties of Ni0.4Zn0.2Mn0.4Fe2O4 potential for radar absorbing

Zuschriften Critical Enhancements of MRI Contrast and Hyperthermic Effects by

Sintering thermodynamics of fields activated microforming and sintering technology for fabricated MnZn ferrite microparts

Self-propagating high-temperature synthesis of MnZnferrites for inductor applications

The role of prefiring in the development of Mn-Zn spinel ferrites for inductive power transfer

Facile synthesis and characterization of Mn x Zn 1-x Fe 2 O 4 /activated carbon composites for biomedical applications

Development of nanocrystalline Mn-Zn ferrites for forward type DC-DC converter for switching mode power supplies

Magnetic, dielectric, and complex impedance properties of nanocrystalline Mn-Zn ferrites prepared by novel combustion method

The role of nanotechnology in the treatment of viral infections

Giant magnetoresistance-based biosensor for detection of influenza A virus

Figure 14: TEM image of Mn 1-x Zn x Fe 2 O 4 system prepared using gelatin method (Reproduced by permission from Ref

), (b) Hysteresis loop of MnZn ferrite with Samarium doping where x is Sm concentration having (a) x=0.0, (b) x=0.1, (c) x=0.3 and (d) x=0

Temperature dependance of power loss with SnO 2 addition (Reproduced by permission from Ref

The General Editor Ceramic International Dear Editor, Here, I want to state that the review work is our original work and all authors agreed to submit in Ceramic International.We hope that you will appreciate our contribution and will consider the topic suitable for possible publication in Ceramic International as a full length review paper. Once again thank you for your time and careful consideration of our work.

Prof Atul Thakur