Evolution of the Crystal Structure of RVO3 (R = La, Ce, Pr, Nd, Tb, Ho, Er, Tm, Yb, Lu, Y) Perovskites from Neutron Powder Diffraction Data

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• 作者：M. J. Mart&#xed ; nez-Lope ; J. A. Alonso ; M. Retuerto ; M. T. Ferná ; ndez-D&#xed ; az
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：April 7, 2008
• 年：2008
• 卷：47
• 期：7
• 页码：2634 - 2640
• 全文大小：1510K
• 年卷期：v.47,no.7(April 7, 2008)
• ISSN：1520-510X

文摘

RVO₃ perovskites have been prepared in the widest range of R³⁺ ionic size, from LaVO₃ to LuVO₃. Pure polycrystalline samples have been obtained by a citrate technique leading to reactive RVO₄ precursors, followed by thermal treatments in a reducing H₂/N₂ (15/85%) flow to stabilize V³⁺ cations. These oxides have been studied at room temperature by high-resolution neutron powder diffraction to follow the evolution of the crystal structures along the series. The distortion of the orthorhombic perovskite (space group Pbnm), characterized by the tilting angle of the VO₆ octahedra, progressively increases from La to Lu due to simple steric factors. Additionally, all of the perovskites show a subtle distortion of the VO₆ octahedra which significantly increases from La to Tb, and then slightly decreases for the last terms of the series. The stability of the crystal structure is also discussed in light of bond-valence arguments.