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Structural analysis of excess‐anion C‐type rare earth oxide: a case study with Gd 1− x Ce x O 1.5+ x /2 ( x = 0.20 and 0.40)
Author(s) -
Grover V.,
Achary S. N.,
Tyagi A. K.
Publication year - 2003
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889803010288
Subject(s) - crystallography , ion , crystal structure , chemistry , rietveld refinement , metal , x ray crystallography , oxide , coordination number , powder diffraction , rare earth , diffraction , mineralogy , physics , organic chemistry , optics
Structural analysis of anion‐rich C‐type Gd 2 O 3 was carried by the Rietveld refinement of the powder X‐ray diffraction data for compositions Gd 0.8 Ce 0.2 O 1.60 and Gd 0.6 Ce 0.4 O 1.70 . Both compounds have a body‐centred cubic lattice (space group Ia , No. 206, Z = 32) with unit‐cell parameters of 10.8488 (1) and 10.8542 (1) Å, respectively. Both of these compounds are iso‐structural with the C‐type rare earth oxides, with excess anions as required for charge balance. The structural analysis reveals that there are two different kinds of metal ion site, namely 8 b ( M 1) and 24 d ( M 2), and two different kinds of anion sites, namely 48 e (O1) and 16 c (O2). The excess anions occupy the 16 c ( xxx ) sites. The two metal ions each form an approximately eightfold‐coordination polyhedron with O1 and O2. The details of these two compositions are explained and compared with both the CeO 2 structure and the Gd 2 O 3 structure, i.e. the end member.