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ORNL P
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MICROCOPY RESOLUTION TEST CHART
NATIONAL BUREAU OF STANDARDS - 1963

OPNL-P-1158
(For submission as "Journal Note" in Journal of American Ceramic Society)
ORNI - AIC OFFICIAL
APR 27 1965
RELEASED FOR ANNOUNCEMENT
MASTER
.AIC - OSSICIAL

IN NUCLEAR SCIENCE ABSTRACTS
where
UOLICAR
ROPERTIES
d erno
STRUCTURAL PROPERTIES OF THIRTEEN TYPE-41. RARE EARTH OXIDESR
P
SINTERED AT 1600°c*.
VAM article
C. E. Curtis, Consultant
Metals and Ceramics Division
Oak Ridge National Laboratory
Oak Ridge, Tennessee
•;" ter worden door home or forrientering mo
.
CFSTI PRICES
H.C. $ 7.00;MNS
Crystal structure and petrographic data were obtained for sintered
oxides of 13 type-4f rare earth elements, promethium oxide being the only
one in this series not investigated. The oxides were 99.1% pure or better
except for the Sta, Oz which contained 1.4% impurities. The major impurities
were other rare earth elements and yttrium (usually less than 0.05%).
Pellets 1/8 in. in diameter and 1/4 in. long were cold pressed from
available oxide powders at 7.5 tsi and sintered in an alumina crucible in
a slow stream of oxygen on the following schedule: 3 hr to 1600°C, 1 hr
at 1600°c, approximately 3 hr to cool to room temperature. X-ray dif-
fraction patterns were obtained by the diffractometer technique with
Cuka (1= 1.54178 Å) radiation and 20 scans of 20 to 60°. The immersion
method was used in petrographic examinations.
indicated in the table, unresolvable diffraction lines extraneous to those
of the major phase were noted in several cases. The presence of these
lines may be attributable to the fact that equilibrium structures had not
ORNI - AEC
*Research sponsored by the U.S. Atomic Energy Commission under
contract with the Union Carbide Corporation.
-LEGAL NOTICE –
ORNI - AEC - OFFICIAL
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Table I. Results of X-Ray Diffraction Studies
on Rare Earth Oxides
A
"
with **
Structure of
Phases
Identified
Oxide
a (A)
B.(A)
(A)
INI
Bldes)
CeO2
fcca(fluorite)
fcc(fluorite)
hex(A-form)
5.403 1 0.004
3.457 + 0.005
Be
:
Pr6021
Pr203
.
Nd203
Mia's workin
Sm203
6.02 + 0.01
5.988 $ 0.006
8.847 + 0.008
8.676 + 0.008
8.760 $ 0.008
reagaimawth
3.633 + 0.006
3.581 + 0.006
3.566 + 0.006
Eu203
99,96
*98.5
100.1
G4203
T0407
Dy203
Ho203
Er203
Tm203
Yb203
Luzoz
hex@(A-form)
monocle(B-form)
monoc18(B-form)
monocl(B-form)
fcc@(fluorite)
bcc (C-form)
bcc(c-form)
bcc(C-form)
bcc (C-form)
bcc(C-form)
bcc(C-form)
3.822 + 0.003
14.177 + 0.010
13.944 $ 0.006
24.061 + 0.010
5.301 + 0.004
10.651 + 0.008
10.576 + 0.005
10.506 + 0.006
10.465 + 0.005
10.417 + 0.004
10.370 0.004
Unidentified extraneous lines also present.
always obtained under the cooling conditions used. In the case of the
Pr oxide, the extra lines were identified as being due to a minor pro-
portion of the hexagonal (A-form) sesquioxide which apparently had not
Inverted to the bcc C-form on cooling. Patterns for the oxides of Sm,
Era, and Gd were identified as those of the monoclinic B-form of the
sesquioxides, ladicating that inversion to the low-temperature C-form
had not occurred under the cooling conditions used. ..
The petrographic data shown in Table II are consistent with the
X-ray diffraction analyses. The anisotropy of the oxides of Stua, Eu,
and Ga indicated that the monoclinic form was present. The oxides of
Pr and Na could not be evaluated by this technique because of their
opacity.
The sintered pellets were stable in air at room temperature ex-
cept for those of the oxides of Pr and nd which disintegrated within a
few hours. Accelerated weight loss occurred at 675°C and 975°C when
the hydration product of the Pr oxides was heated in air.
The author wishes to acknowledge the assistance of R. M. Steele
and L. A. Harris for the x-ray determinations and of Dr. T. N. McVay
for the petrographic studies
41. Warshaw, Rustum Roy, Polymorphism of the Rare Earth Sesquioxides,
J. Phys. Chem. 65(11), 2048-51 (1961).
ORNL - ACC - OFFICIA
Table II. Results of Petrographic Studies on Rare Earth Oxides
Probable
Ooxide Form
Optical Character
of Main Constituents
.
Index of Refraction
ca. 2.38
Ceog
Praz
Isotropic
Indeterminatea
Naz 3
Indeterminated
Sm3
Indeterminate +
Biaxial Negative
Blog
Anisotropic
G0203
EROT
DJ 203
Anisotropic
Isotropic
2.04(a), 2.08(7)
(2v = 200)
2.04(0);2.04(E)
2.02 to 2.04
ca. 2.00
ca. 2.00
1.98
1.96
1.95 to 1.96
Isotropic
Isotropic
Isotropic
Br2O3
Tranzos
Isotropic
Yoel3
Isotropic
1.95
Ilz03
Isotropic
1.93
especimens were opaque.
-- ORNE - AEC - OFFICIAL

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