The vibrational properties of tetragonal tungsten-bronze lead barium niobate, Pb (1−x) BaxNb 2 O 6 , with x = 0.5 were investigated by using Raman spectroscopy over a wide temperature range from room temperature to 550 °C. The Raman modes in the measured spectrum were divided into three spectral ranges, internal symmetric and antisymmetric vibrational modes of the oxygen octahedra and low-frequency external lattice modes. The temperature dependences of the Raman shifts showed anomalous changes at the ferroelectric phase transition temperature of ~350 °C. Especially, lowfrequency modes below ~300 cm −1 commonly exhibited multiple softening upon heating toward the transition temperature, indicating that the lattice becomes softer on approaching the ferroelectric phase transition temperature.

中文翻译：

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钨-青铜铅铌酸钡弛豫铁电单晶低频拉曼模式的多重软化

通过使用拉曼光谱在从室温到 550 °C 的宽温度范围内研究了四方钨青铜铌酸钡铅 Pb (1-x) BaxNb 2 O 6 的振动特性，其中 x = 0.5。测量光谱中的拉曼模式分为三个光谱范围，氧八面体的内部对称和反对称振动模式以及低频外部晶格模式。拉曼位移的温度依赖性在约 350 °C 的铁电相变温度下显示出异常变化。特别是，低于~300 cm -1 的低频模式通常在向转变温度加热时表现出多次软化，表明在接近铁电相变温度时晶格变得更软。