Thermal expansion of mullite-type Bi{sub 2}Al{sub 4}O{sub 9}: A study by X-ray diffraction, vibrational spectroscopy and density functional theory
Thermal expansion of mullite-type Bi{sub 2}Al{sub 4}O{sub 9}: A study by X-ray diffraction, vibrational spectroscopy and density functional theory
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莫来石型Bi{sub 2}Al{sub 4}O{sub 9}的热膨胀：X射线衍射、振动光谱和密度泛函理论研究
DOI：
10.1016/j.jssc.2015.05.010
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发表时间：
2015
影响因子：
3.3
通讯作者：
Th. M.
中科院分区：
文献类型：
--
作者：
Murshed;Mendive;Sehovic;Friedrich;Fischer;Gesing;Th. M.
采用甘油法合成了Bi2Al4O9多晶粉末样品。在Bi 2 O 3熔体中由粉末产物产生单晶。利用X射线衍射、拉曼光谱和密度泛函理论研究了莫来石型化合物的晶格热膨胀。度规参数采用Grüneisen近似建立，其中依赖于温度的振动内能由德拜特征频率计算。一阶和二阶Grüneisen近似都被应用于体积膨胀建模，二阶方法提供了物理上有意义的轴向参数。利用声子态密度和声子色散指导设定模拟的特征频率。将实验得到的红外和拉曼声子谱与DFT计算结果进行了比较。利用简化的Klemens模型分析了选择性拉曼模的热非谐行为。由压力依赖的拉曼光谱计算了相应的模式Grüneisen参数。
Polycrystalline Bi2Al4O9powder samples were synthesized using the glycerine method. Single crystals were produced from the powder product in a Bi2O3melt. The lattice thermal expansion of the mullite-type compound was studied using X-ray diffraction, Raman spectroscopy and density functional theory (DFT). The metric parameters were modeled using Grüneisen approximation for the zero pressure equation of state, where the temperature-dependent vibrational internal energy was calculated from the Debye characteristic frequency. Both the first-order and second-order Grüneisen approximations were applied for modeling the volumetric expansion, and the second-order approach provided physically meaningful axial parameters. The phonon density of states as well as phonon dispersion guided to set the characteristic frequency for simulation. The experimental infrared and Raman phonon bands were compared with those calculate from the DFT calculations. Selective Raman modes were analyzed for the thermal anharmonic behaviors using simplified Klemens model. The respective mode Grüneisen parameters were calculated from the pressure-dependent Raman spectra.