Abstract In order to clarify ordering mechanisms of ferroic phase transitions in double fluoride salts (NH4)3SnF7, (NH4)3GeF7 and (NH4)3TiF7, their Raman scattering spectra have been studied in wide ranges of frequencies (20–3400 cm−1) and temperatures (8–410 K). Substitution of the central ion in the octahedron groups was found to change not only the phase transition types and sequences, but to modify the types of structural disorder as well, which is a special feature of these high-symmetry fluoride crystals.

中文翻译：

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拉曼光谱在双氟化物晶体家族中的铁弹性相变

摘要 为了阐明双氟化物盐 (NH4)3SnF7、(NH4)3GeF7 和 (NH4)3TiF7 中铁质相变的有序机制，研究了它们在宽频率范围 (20–3400 cm-1) 下的拉曼散射光谱。和温度 (8–410 K)。发现八面体基团中中心离子的取代不仅改变了相变类型和序列，而且还改变了结构无序的类型，这是这些高对称氟化物晶体的一个特殊特征。