Vibrational spectroscopy and x-ray diffraction of Perovskite compounds Sr(1-x)M(x)TiO(3) (M=Ca,Mg; 0
Vibrational spectroscopy and x-ray diffraction of Perovskite compounds Sr(1-x)M(x)TiO(3) (M=Ca,Mg; 0
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DOI：
10.1006/jssc.1996.0249
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发表时间：
1996-07-01
影响因子：
3.3
通讯作者：
Kitajima, M
中科院分区：
文献类型：
--
作者：
Hirata, T;Ishioka, K;Kitajima, M
采用固相反应法合成了一系列钙钛矿型化合物Sr（1-x）M（x）TiO（3）（M = Ca，Mg; 0 ≤ x ≤ 1），并用傅里叶变换红外光谱、拉曼散射和X射线衍射对其进行了表征。对于Sr 1-xCaxTiO 3，发现在宽的x范围内形成替代固溶体，而当x大于或等于0.6时会出现痕量的正交CaTiO 3。立方SrTiO 3的晶胞体积随着Sr被具有较小离子半径的Ca取代而减小，并且Sr-O键长的减小与Ti-O键的缩短在一定程度上相匹配。Ti-O-3扭转模的460 cm（-1）拉曼谱带出现在x = 0.6处，并随着x的增加而上移。另一方面，固溶体的形成被限制为x小于或等于0.2的Sr 1-xMgxTiO 3的拉曼/红外反射光谱和X射线衍射轮廓的Sr 1-xMgxTiO 3的立方SrTiO 3和六方MgTiO 3的共存的特征。根据A（II）B（IV）O（3）的焓与容限因子之间的关系，讨论了Ca或Mg在SrTiO 3中的溶解度。可以得出结论，MgTiO 3与SrTiO 3的低效混合主要是由Sr 2+和Mg 2+阳离子半径之间的实质性差异;这解释了较不稳定的Sr 1-xMgxTiO 3和Mg在SrTiO 3中的更有限的溶解度，以及通过SrTiO 3和MgTiO 3与CaTiO 3相比的公差因子的有效差异。(C)出版社：Academic Press，Inc.
A series of perovskite compounds, Sr(1-x)M(x)TiO(3) (M = Ca, Mg; 0 less than or equal to x less than or equal to 1), has been synthesized by solid-state reaction, and characterized by Fourier-transform infrared spectroscopy, Raman scattering, and X-ray diffraction. As for Sr1-xCaxTiO3, it was found that the substitutional solid solutions are formed over a wide x range, whereas traces of orthorhombic CaTiO3 would appear for x greater than or equal to 0.6. The unit-cell volume of cubic SrTiO3 decreases as Sr is replaced by Ca with a smaller ionic radius, and the Sr-O bond length reduction is somewhat matched by the Ti-O bond shortening. The latter is evidenced by the fact that the 460 cm(-1) Raman band assigned to the Ti-O-3 torsional mode appears at x = 0.6 and shifts upward with further increasing x. On the other hand, the formation of solid solutions is restricted to x less than or equal to 0.2 for Sr1-xMgxTiO3; the Raman/infrared-reflectivity spectra and X-ray diffraction profiles of Sr1-xMgxTiO3 are characteristic of the coexistence of cubic SrTiO3 and hexagonal MgTiO3. The solubility of Ca or Mg in SrTiO3 is discussed based on the correlation between the enthalpy and tolerance factors for A(II)B(IV)O(3). It is concluded that inefficient mixing of MgTiO3 with SrTiO3 is predominated by the substantial difference between the Sr2+ and Mg2+ cation radii; this accounts for the less stable Sr1-xMgxTiO3 and the more limited solubility of Mg in SrTiO3 as well, through the effective difference in the tolerance factors of SrTiO3 and MgTiO3 as compared with CaTiO3. (C) 1996 Academic Press, Inc.