Transitions Between Lanthanum Cuprates: Crystal Structures of T′, Orthorhombic, and K2NiF4‐type La2CuO4
Transitions Between Lanthanum Cuprates: Crystal Structures of T′, Orthorhombic, and K2NiF4‐type La2CuO4
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铜镧酸盐之间的转变：T、斜方和 K2NiF4 型 La2CuO4 的晶体结构
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
B. Albert
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作者：
Roland Hord;G. Cordier;K. Hofmann;A. Buckow;G. Pascua;H. Luetkens;L. Alff;B. Albert
在CsOH助熔剂中低温合成cu2cuo4，可以得到亚稳态的cu2cuo4，即所谓的T '修饰(四方型，I4/mmm, no。139, a = 400.95（2) pm, c = 1254.08(7) pm）。当加热时，这种T′相转变为k2nif4型改性物，其晶体结构现在从x射线粉末数据中得到改进(四方，I4/mmm, no。在T = 1073 K时，a = 383.29(3) pm, c = 1331.3(2) pm。众所周知的正交相(s.g.c mce, no。64, a = 536.14(3) pm, b = 1315.53(8) pm, c = 540.20(3) pm) -通常通过传统的固态合成得到-由k2nif4型改性冷却后形成。高温粉末衍射法可以对所有三相的晶体结构进行细化。
Through low-temperature synthesis in CsOH flux, lanthanum cuprate La2CuO4 can be obtained in a metastable form, the so-called T′ modification (tetragonal, I4/mmm, no. 139, a = 400.95(2) pm, c = 1254.08(7) pm). When heated, this T′ phase transforms into a K2NiF4-type modification, whose crystal structure was now refined from X-ray powder data (tetragonal, I4/mmm, no. 139, a = 383.29(3) pm, c = 1331.3(2) pm at T = 1073 K). The well-known orthorhombic phase (s.g. Cmce, no. 64, a = 536.14(3) pm, b = 1315.53(8) pm, c = 540.20(3) pm) – usually obtained via conventional solid state synthesis – was observed to form upon cooling from the K2NiF4-type modification. High-temperature powder diffractometry allowed crystal structure refinements for all of the three phases.