Anisotropic thermal expansion and anharmonic phonon behavior of mullite-type Bi2Ga4O9
Anisotropic thermal expansion and anharmonic phonon behavior of mullite-type Bi2Ga4O9
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DOI：
10.1016/j.materresbull.2013.05.007
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发表时间：
2013-09
影响因子：
5.4
通讯作者：
M. Murshed;T. Gesing
中科院分区：
文献类型：
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作者：
M. Murshed;T. Gesing
我们报道了莫来石型bi2ga4o9配合氧化物的晶格热膨胀和温度依赖声子行为。利用粉末和单晶x射线衍射在100K ~ 1273K范围内的复合数据研究了热膨胀。晶格展开的顺序为a<c<b。利用热膨胀系数和各向异性系数监测了各向异性膨胀行为。体积热膨胀用零压力状态方程的扩展grisen一阶近似表示；该模型包括调和、准调和和本征非调和对内能的贡献作为温度的函数。在78K ~ 1273K范围内采集了单晶的温度相关拉曼光谱。频率随温度的变化和线宽随温度的增加，有助于分析某些声子的非谐性和热行为。
We report the lattice thermal expansion and the temperature-dependent phonon behavior of the mullite-type Bi2Ga4O9complex oxide. The thermal expansion was studied using composite data collected from powder and single crystal X-ray diffraction between 100K and 1273K. The lattice expansion occurred in the order of a<c<b. The anisotropic expansion behavior was monitored with respect to thermal expansion coefficients and the anisotropy factor. The volume thermal expansion was expressed using an extended Grüneisen first-order approximation to the zero-pressure equation of state; the model includes harmonic, quasi-harmonic and intrinsic anharmonic contributions to the internal energy as a function of temperature. The temperature dependent Raman spectra were collected from a single crystal between 78K and 1273K. The shift of the frequencies and the broadening of the line-widths with increasing temperature helped to analyze the anharmonicity and the thermal behavior of some phonons.