Crystal Chemistry and Phase Equilibria Studies of the BaO-R2O3-CuO Systems. II: X-Ray Characterization and Standard Patterns of BaR2O4, R = Lanthanides
| Autor: | Boris Paretzkin, Winnie Wong-Ng |
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| Rok vydání: | 1991 |
| Předmět: | |
| Zdroj: | Powder Diffraction. 6:187-189 |
| ISSN: | 1945-7413 0885-7156 |
| DOI: | 10.1017/s0885715600017486 |
| Popis: | The compounds BaR2O4, where R = La, Nd, Sm, Gd, Eu, Dy, Ho and Er have been prepared from a stoichiometric mixture of BaCO3 and lanthanide oxides, and characterized by X-ray powder diffraction. Standard X-ray patterns of these phases were prepared. In general, BaR2O4 crystallizes in the pervoskite-related CaFe2O4 structure which is orthorhombic with a space group Pnam. The cell parameters of these compounds from R = Er to La range from 10.3729(12) to 10.668(2) Å for a, 12.0699(11) to 12.642(2) Å for b, from 3.4356(4) to 3.7037(10) Å for c, and from 450.14(5) Å3 to 499.51 Å3 for V respectively. A monotonic, linear relationship is obtained when V is plotted against the cube of the ionic radius of R. When R = Tm, Lu and Yb, the BaO·R2O3 composition produced the mixture Ba3R4O9 and the unreacted lanthanide oxide. Under the present experimental conditions, the compound BaRO3 was the predominant component when R = Ce, Pr, and Tb. |
| Databáze: | OpenAIRE |
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