高压下铌酸锌钶铁矿结构相变的原位拉曼光谱和X射线衍射研究

通过原位高压拉曼光谱和X射线衍射对ZnNb₂O₆晶体在29 GPa以下的结构转变进行了研究.拉曼光谱显示, 多数拉曼峰强度减弱, 且随着压力增加向高波数方向移动.压力频移曲线分别在10, 16 和20 GPa处形成了拐点.原位X射线衍射谱在10.6 GPa以上有旧峰消失和新峰出现.结果分析表明, ZnNb₂O₆钶铁矿结构压缩过程中发生了一个可逆压致相变, 此相变从10 GPa左右开始, 到16 GPa左右完成, 继续增加压力到20 GPa以上则形成无序状态.

In-situ Raman Spectra and X-ray Diffraction Study on Pressure-induced Phase Transition in Columbite ZnNb2O6

In-situ high pressure studies of ZnNb₂O₆ have been performed using Raman spectroscopy and synchrotron X-ray diffraction in a diamond anvil cell up to 29 GPa. Raman experiments show that most Raman peaks decrease in intensity and shift toward high wavenumbers with increasing pressure. Three turn points in the slope of frequency-pressure curve of Raman modes turn up at the pressure around 10, 16 and 20 GPa. Angle dispersive X-ray diffraction results display that some old peaks disappear and some new peaks appear above 10.6 GPa. Both Raman and X-ray diffraction data provide evidence of a reversible phase transition which begins from about 10 GPa and complets at 16 GPa, and then a disorder state is formed above 20 GPa.