First-principle calculation and assignment for vibrational spectra of Ba(Mg1/3Nb2/3)O3 microwave dielectric ceramic
First-principle calculation and assignment for vibrational spectra of Ba(Mg1/3Nb2/3)O3 microwave dielectric ceramic
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DOI：
10.1063/1.4868226
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发表时间：
2014-03-21
影响因子：
3.2
通讯作者：
Jing, Xi-Ping
中科院分区：
文献类型：
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作者：
Diao, Chuan-Ling;Wang, Chun-Hai;Jing, Xi-Ping
采用传统的固相反应法，在1600 ℃下反应12 h，合成了1：2 B位阳离子有序Ba（Mg 1/3 Nb 2/3）O3陶瓷。通过Rietveld精修的X射线衍射数据得到的结构参数。通过对拉曼光谱进行洛伦兹拟合，得到了各拉曼峰的频率。采用四参数半量子模型对红外反射率谱进行了拟合，并利用拟合的参数计算了介电常数ε和介电损耗tan δ。采用基于密度泛函理论和局域密度近似的第一性原理计算方法，得到了9个活性拉曼模和16个活性红外模。所有的振动模式被分配和表示的对称坐标的线性组合推导出使用群论分析。具有最高频率A（1g）（（4））（789 cm（-1））的拉曼模式可以描述为NbO 6的呼吸振动。红外模式E-u（（1））（149 cm（-1））和A（2u）（（2））（212 cm（-1））分别是Ba-MgO 6/Ba-Nb O 6在a-b平面上的扭曲振动和Ba-MgO 6/Ba-Nb O 6在c方向上的沿着伸缩振动，它们是对α和tan δ的主要贡献模式。使用红外光谱拟合，第一原理计算，微波测量得到的介电性能参数进行了比较。(C)2014 AIP Publishing LLC.
1:2 B-site cation ordered Ba(Mg1/3Nb2/3)O-3 ceramic was synthesized using conventional solid-state reaction at 1600 degrees C for 12 h. The structure parameters were obtained through Rietveld refinement of X-ray diffraction data. The Raman peak frequencies were obtained by Lorenz fitting on Raman spectrum. Four-parameter semiquantum model was used to fit the infrared (IR) reflectivity spectrum, and the fitted parameters were used to calculate the dielectric permittivity epsilon and dielectric loss tan delta. A total of 9 active Raman and 16 active IR modes were obtained using first-principle calculations based on density functional theory with local density approximation. All of the vibrational modes were assigned and represented by linear combinations of the symmetry coordinates deduced using group theory analysis. The Raman mode with the highest frequency A(1g)((4)) (789 cm(-1)) can be described as the breathing vibration of NbO6. The IR modes E-u((1)) (149 cm(-1)) and A(2u)((2)) (212 cm(-1)), which can be described as the twisting vibrations of Ba-MgO6/Ba-NbO6 on the a-b plane and the stretching vibrations of Ba-MgO6/Ba-NbO6 along the c direction, respectively, are the dominant contributing modes to epsilon and tan delta. The dielectric property parameters obtained using IR spectrum fittings, first-principal calculations, and microwave measurements were compared. (C) 2014 AIP Publishing LLC.