正铁氧体SmFeO_3高压拉曼研究(英文)  

High Pressure Raman Study of Orthoferrite SmFeO_3

作　　者：李娜娜[1] 李会[1] 唐瑞莲 韩丹丹[1] 朱品文[1] 王欣[1] 

机构地区：[1]超硬材料国家重点实验室,吉林大学,长春130012

出　　处：《光散射学报》2014年第2期148-153,共6页The Journal of Light Scattering

基　　金：国家基础科学人才培养基金资助项目(NO.J1103202);国家自然科学基金项目(51172091);新世纪优秀人才支持计划资助(NCET-12-0240);吉林省科技发展计划资助项目(20130101023JC)

摘　　要：本文主要通过高压拉曼光谱研究了正铁氧体SmFeO3的晶格振动模式在外加压力作用下的行为规律,高压实验中压力最高为29.7GPa。本文采用溶胶凝胶法,制备出具有正交结构,其空间群为Pnma的SmFeO3。在外加压力作用下,所有观察到的拉曼振动模式都呈现出宽化趋势。特别是位于621.1cm-1的FeO6八面体的反弹性振动模式Ag(1)与位于452.7cm-1的FeO6八面体的弯曲振动模式B3g(3),其压力系数出现最大值。与此相反,Sm-O振动模式Ag(7)的压力系数却非常小。这说明外加压力更容易影响到FeO6八面体的晶格变化,而不是SmO12十七面体的改变。SmFeO3的这种高压下晶格振动模式变化行为类似于G型结构的CaSnO3。同时,文中还给出了所有声子零压模式下的格林爱森参数与体弹模量的比值。这些参数可用于进一步测量单轴或者双轴的应变力,可深入理解声子频率在张力作用下移动的表现行为。The spectroscopic properties of SmFeO3 had been investigated by Raman spectroscopy in a diamond anvil cell（DAC）up to 29.7GPa at room temperature.At ambient pressure,SmFeO3 was in a distorted orthorhombic structure with space group Pnma.All the observed Raman modes exhibited broadening effect under high pressure.The vibrational band Ag（1）around 621.1cm^-1 and B3g（3）around 452.7cm^-1 which were associated with the anti-stretching vibrations of FeO6 octahedra and bending mode of FeO6 octahedra respectively,had the largest pressure coefficient.On the other hand,the pressure coefficient of a singlet（Ag（7））related with Sm-O vibrations was very small.Therefore,the pressure had stronger effects on the vibrations of the FeO6octahedra than the SmO12 polyhedra.The high-pressure behavior of SmFeO3 was also similar with G-type CaSnO3.The ratio of the zero pressure mode Grüneisen parameter to the bulk modulus for all the observed phonon modes had been calculated and presented.These parameters could be used to evaluate the amount of uniaxial or biaxial strains,providing a fundamental tool for monitoring the magnitude of the shift of phonon frequencies with strains.

关 键 词：高压 正铁氧体 拉曼光谱 

分 类 号：O521.21[理学—高压高温物理]