6 - . *is . > * 2 ss . : : I OF I ORNL P 2439 1 a * 2 ! 1 > . l 93.2 36 . . F4O . . . MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF MTANDARDS - 1963 . 's ORNL-P-2439 Con4-660813-) CFSTI PRICES SEP 2 2 1956 HC. $1.00; Mu 5-0 The Examination of Praseodymium and Europium Hydroxide Sols by Electron Microscopy and Electron Diffraction* MASTER T. E. Willmarth Oak Ridge National Laboratory Analytical Chemistry Division P. 0. Box X Oak Ridge, Tennessee RELEASED FOR ANNOUNCEMENT IN NUCLEAR SCIENCE ABSTRACTS .. LEGAL NOTICE This roport was prepared us an account of Government spuogored mrk. Nelther ebe United Suton, nor the Commission, nor any person ucung on behalf of the Commission: A. Makes any warrunty or representation, expressed or implied, with respect to the accu. racy, completeness, or usefulness of the i vormation coolained in this report, or lat we use of any information, apparatus, method, or process dixcloseu la this report may not infringe privately owned righus; or B. Asrumcs way liabilities de respect to the use of, or for damages resulung from the .. . . ............ As wrod to the above, "perkon acting op beball of the Commission" includes way eno- Hogue or coalnıctor of the Commission, or empioyee of such coulrac'or, to the extent that such employee or coatructor of the Commission, or employee of such contraclor prepares, disseminates, or provides access to, nay lnfno illon pursuant lo dis employment or contact with the Commission, or kilo employment with such contractor. . :.. . . . . . . . . ... Research sponsored by the U. S. Atomic Energy Commission under contract with the Union Carbide Corporation. .. . ... ... -. . : : .. ...Ma ly h y! WWW." Ilmy porn .. . . . .. Table of Contents 1. Introduction .. Preparation o2 Sample Material 2.1 Sole 2.2 Hydroxide Sol Cel Microspheres 3. Results 3.1 Changes in the Physical Structure of the Sols due to aging .. .. .. .... 3.2 Ultrathin Sections .......... 4. Conclusion .... . .. Wo... ... . -. .. ... . . . . . . . . . . . 1. Introduction Electron microscopy and selected area transmission electron diffraction have been used extensively in support of a program, conducted by C. J. Hardy**, Ridge National Laboratory, aimed at producing microspheres of the lanthanide .. oxides with a density close to the theoretical crystal density, and a high .. ... crushing strength. The knowledge gained from this project will be applied to the production of americium and curium oxides suitable for employment .. .... as targets in the High Flux Isotope Restor. Certain lanthanide oxides, as ......... microspheres may also be usefui as control rods, and as burneble poisons ... . . ....... sols of erbium, europium, nendymium, praseodymium, and samarium were examined. Only two of these, europium and praseodymium, will be discussed in this paper. . 2. . Preparation oỉ Sanple Material for Electron Microscopy and Diffraction ... .. .. . .. . ... . .. 2.1 Sols (Prepared by addition of Lanthanide Nitrate Solution to NH,OH) Each sample of a fraction of a ml. of the hydroxide sol was diluted about 100 fold with co, free distilled water, and 1 droplet of this sol was placed on a formver coated 200 mesh grid and inserted into the electron microscope, a Philips FM 200. The image on the fluorescent screen, in all cases, *28 observed, focussed, and photographically recorded on 3 1/4 x 4 lantern slide contrast plates within ten minutes after taking the sample. 2.2 Hydroxide Sol Gel Microspheres Sol gel microspheres were mounted in epoxy (Araldite), and ultrathin ... . . sections cut on a IXB Ultratome using a glass knife. 3. Results 3.1 Changes in the Physical Structure of the Sols due to Aging. Using a pre-established time schedule for each sol sample, the hydroxida **Guest scientist from the Chemistry Division, Atomic Energy Research Establishment Harwell, England . *Nokia finisce powodowania , . ........................ gols of europium and praseodymium were examined in the electron microscope to determine the effect of aging. Electron diffraction patterns were made on selected areas 1 micron X 1 micron of the sols to determine the exorphous or crystalline nature of the observed particles. Tke details of the sanples exemlued are given in Tahle 1. The appearance of the sols at pertinent times 18 shown in Fig. é and . Size data of the particles from the electron micrographs 18 tabulated in Table 2. The diffraction patterns, corresponding with the pictures, are displayed in F48. and . Lattice spacings of the crystalline hydroxddes of europium and praseodymium obtained by measurement of the diffraction pattern negative plates are showa 1.0 Teble 3. The spazing of the diffraction lines agree very closely with the published X-ray data- for Eu(OH)z, and differ significantly from those expected for Eu00H. No X-ray data was found in the literature for Pr(OH)z. Intensities of the lines for the Eu(OH)2, because of an apparent preferred orientation of the elongated crystals in relation to the electron beam, vary from those reported in X-ray measurements. 3.2 Ultrathin Sections of Hydroxide Microspheres. Although stereo electron micrographs, at high magnification, indicated many crystals were not lying at a 90° angle to the electron beam, no reliable information could be obtained concerning their cross section shape or dimensions. Microtoming was therefore used in an attempt to determine this. Sections of approximately 200 angstroms thickness were microtomed and examined at a magnification of 125,000 X. Fig. 8. A randomly orier: d array of elongated crystals, and bundles of crystals was observed with occasional approximately square cross-sections where portions of the crystals in the mount allowed them to be cut at close to a normal angle with the C-axds. The width or diameter of the bundles varied from 60 to 150 Å. The smallest width or dianje ter of any rod observed, either in the microtomed sections or the sol dispersions, was 20 Å. 4. Conclusion Electron lucroscope studies show striking metamorphic alterations take place in the hydroxide sols of the lanthanide elements as aging proceeds, with considerable difference, time-wise, from element to element as to when the change from & nearly amorphous state to the crystalline state takes place, and when maximum growtb is achieved. Depending on the element involved, crystal size at the maximum. also varies considerably. In turn, this effects the physical nature of the final oxide microspheres. This report has shown the role of electron microscopy and electron diffraction as applied to a specific problem of chemd cal technology involving the morphology of praseodymium and evropium hydroxide sols. The information obtained hes pointed the way to better specifications of density and hardness. Acknowledgment The preparation of the sauple material by S. R. Buxton, the wtrathin sectious work by T. G. Harmon, and the assistance of C. J. Hardy in assembling this report, are gratefully acknowledged. - - - - -- - -- -- -- =- - - - - - -- - - - - 3 - ** . . --- - - -- - - - - - . G '. *.= . . . . . . . - - - - . . . . . . - *. - * -79 E U R , Z ' 7.- Vol. II, p. 117. 1. Robert C. Rau (1963) Proceedings 3rd Conference on Rare Earth Research References Table 1 Sols examined by Electron Microscopy and shown in Figs. 2 and 3 Metal Sol Sample No. and Fig. No. Preparation and Treatment Tine of Ageing at 25°C from Precipitation to Electron Microscopy Pr 13 min 95-1 Fig. 2A Freshly precipitated hydroxide centrifuged from mother liquor (20 x excess NH,,OH). Pr 80 min 95-2 Fig. 2B Ppt. Washed 5 x H,O with intermediate stirring and centrifuging, NOZ/Pr = 0.19 Pr 95-3 Fig. 20 140 min As 95-2, aged further 60 min until liquefied to translucent sol, Pr = 0.57M Pr 6 days 90 Fig. 2D Prepn similar to 95 sol, but 40 x excess NH, OH, 10 water washes, No,/Pr = 0.21 Eu 20 min 96-1 Fig. 3A Freshly pptd. hydroxide centrifuged from mother liquor Eu 96-2 Fig. 3B Ppt. washed 4 x H40, solia paste. Eu 96-4 As 96-2, kept over weekend 67 hours Fig. 3D 99-1 Fig. 30 Eu 25 hi Similar to 96 sol, but aged 25 hr at 25°C. Very thixotropic translucent liquid sol, Noz/th, = 0.06. PHOTO 83060 . . 1 CAL . 1 SCALE H = 600 Å Electron Micrographs of Praseodymium Hydroxide Sols. A- FRESHLY PRECIPITATED, AGED 18 min. B - PRECIPITATE WASHED, AGED 80 min. C - PRECIPITATE WASHED, AGED 140 min. D - PRECIPITATE WASHED, AGED 6 days PHOTO 83061 -. . - · - w - - - ! - -- SA SCALE H=6008 Electron Micrographs of Europium Hydroxide Sols. A-FRESHLY PRECIPITATED, AGED 20 min. B-PRECIPITATE WASHED, AGED 80 min. C-PRECIPITATE WASHED, AGED 25 hrs. D - PRECIPITATE WASHED , AGED 67 hrs. Table 2 Metal Time of Ageing at 25°C from Precipitation to Electron Microscopy Size, Shape and Crystallinity of Particles 18 Min. 30-60 Ă spherical, amorphous 80 Min. Amorphous particle, and also elongated crystals 300- 700 X long hy 30-90 X wide. 240 Min. All elongated rods, single or as bund).es 400-1000 Å long by 20-200 A wide. 6 days 20 Min. 80 Min. All elongated crystals, or bundles. Sane size ranges. 30-50 Å spherical, amorphous 30-200 Å spher!cal, probebly agglomerates of smaller particles 25 Hrs. Amorphous particles, bundles of elongated crystal 700 to 4000 X long by 50 to 300 X wide. 67 Hrs. Many small amorphous particles, many bundles of elongated crystals 1500 to 7500 Å jong to 100 to 600 A wide. PHOTO 83062 II ID. Electron Diffraction Patterns of Praseodymium Hydroxide Sols. A-FRESHLY PRECIPITATED, AGED 18 min. B - PRECIPITATE WASHED, AGED 80 min. C- PRECIPITATE WASHED, AGED 140 min. D - PRECIPITATE WASHED , AGED 6 days PHOTO 83063 - - - Electron Diffraction Patterns of Europium Hydroxide Sols. A-FRESHLY PRECIPITATED, AGED 20 min. B-PRECIPITATE WASHED , AGED 80 min. C-PRECIPITATE WASHED , AGED 25 hrs. D-PRECIPITATE WASHED , AGED 67 hrs. - - - • - - - - Table 3 Data from Literature (Reference 1) Data from Electron Data from Diff. Patterns. Preparation literature Data from Electron Diff. Preparation (97-3) (96-4) al I/I] hK2 aÅ I/I, do I/I1 hKI HKI 70 100 M 100 M 110 Mt 110 M+ 3 8 101 101 VS 8 200 Wt 200 Wt lll 5.52 3.18 3.05 2.758 2.40 2.204 2.08 1.84 1.822 W+ lll 5.559 3.193 3.077 2.765 2.447 2.216 2.088 1.844 1.832 W+ 6 8 10 201 S- 201 210 W+ 210 VW 300 VS 300 9 8 202 002 M+ 6 211 211 102 o C 1.740 1.588 1.767 1.601 M 220 M- 5.52 3.184 3.047 2.757 2.399 2.202 2.083 1.837 1.828 1.810 1.733 1.589 1.585 1.527 1.524 1.410 1.374 1.295 1.262 1.201 1.194 1.189 1.17.1 1.1135 * 4 4 4 1.52 1.536 102 220 112 310 202 311 212 302 W+ 1.413 W+ 112 310 202 311 212 302 320 410,222 0 - 1.41 1.374 1.292 W W+ 1.307 W+ - - 320 1.209 Wit 9 9 ( 410,222 321 321 1.192 W+ * 103 103 * 312 * 4 a + 203 1.168 1.114 312 203 1.132 W 1. ) * Missing, or Unresolved Lines --- -- - - - - . . . - - - - - - - a...e ----.. .- - . es. mere- . - ::. . S 3 END 3 . DATE FILMED 10/25 / 66 - - - . . .. . . . INS 41 .ili . I. 1. TY wat Kill.. . !! WWW 1: DA MWAN, W TA 11X M WMW '..!! . . . i ,"19 " " i . X .