PbMoO_4原位高压拉曼光谱和电导率的研究

Investigation of in-Situ Raman Spectrum and Electrical Conductivity of PbMoO_4 at High Pressure

钼酸铅（PbMoO4）具有高的声光品质因数、低的声损耗、良好的声阻抗匹配等性质,被广泛应用于声光偏转器、调制器、可调滤光器、声表面波器件等各类声光器件,其优异的低温闪烁性能亦引起人们的注意,具有在核设备方面的应用潜力。为探讨其晶体结构和物理性质,在金刚石对顶砧上原位测量了PbMoO4的拉曼光谱,并测量了其在几个不同压力点下电导率随温度的变化。实验发现,压力在12.5 GPa时,拉曼峰完全消失,说明压力在10.8～12.5 GPa之间PbMoO4样品出现了非晶态转变。当从26.5 GPa卸压到9.4 GPa时,PbMoO4的拉曼谱在低波数出现无序化,而在2.4 GPa压力下858 cm^-1峰又重新出现,说明样品结构由无序向晶化回复。压力在10.8 GPa以上时,电导率随着温度的增加而显著增加,且随着压力的增加也明显增加。

PbMoO4,with high acousto-optic figure of merit,low acoustic loss and nicer acoustic impedance matching,has received much attention because of applications as acousto-optic deflector,modulator,adjustable filter,suface acoustic wave devices and great potential to act as an effective low-temperature scintillator for nuclear instrumental applications.In this study,in-situ Raman spectrum of PbMoO4 was measured in a diamond anvil cell（DAC）.The electrical conductivity measurement of PbMoO4 was performed at different pressure and temperature.All Raman peaks disappeared at 12.5 GPa,which indicated that the PbMoO4 experienced gradually the crystal to amorphous transition between 10.8 GPa and 12.5 GPa.Upon decompresstion from 26.5 GPa to 9.4 GPa a broad Raman peak occurred at a low frequency,while the peak of 858 cm^-1 occured at 2.4 GPa again,thus suggesting that the PbMoO4 crystal was gradually recovered from the amorphous state.Above 10.8 GPa,the electrical conductivity of PbMoO4 increased obviously with increasing temperature and pressure.