| Infrared active phonon modes and ionicity of single crystal MgAl2O4 |
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| 作者姓名： | 毕聪志 马继云 颜俊 方煦 赵柏儒 姚端正 邱祥冈 |
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| 作者单位： | Department of Physics, Wuhan University, Wuhan 430072, China;National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China;National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China;National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China;National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China;National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China;Department of Physics, Wuhan University, Wuhan 430072, China;National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China |
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| 基金项目： | Project supported by the National Natural Science Foundation of China (Grant No 10474128) and Chinese Academy of Sciences. |
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| 摘 要： | Near-normal incident infrared reflectivity spectra of （100） MgAl2O4 spinel single crystal have been measured at different temperatures in the frequency region between 50 and 6000 cm^-1. Eight infrared-active phonon modes are identified, which are fitted with the factorized form of the dielectric function. The dielectric property and optical conductivity of the MgAl2O4 crystal are analysed. From TO/LO splitting, the effective Szigeti charges and Born effective charges at different temperatures are calculated for studying the ionicity and the effect of polarization. Based on the relationship between the （LO-TO）1 splitting, which represents the transverse and longitudinal frequencies splitting of the highest energy phonon band in the reflectivity spectrum, and the ionic-covalent parameter, the four main phonon modes are assigned. MgA1204 can be considered as a pure ionic crystal and its optical characters do not change with decreasing temperature, so it may be used as a suitable substrate for high-Tc superconducting thin films.
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| 关 键 词： | MgAl2O4单晶 声子 电介质函数 有效充量 |
| 收稿时间： | 2005-11-21 |
| 修稿时间： | 3/3/2006 12:00:00 AM |
Infrared active phonon modes and ionicity of single crystal MgAl2O4 |
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| Bi Cong-Zhi,Ma Ji-Yun,Yan Jun,Fang Xu,Zhao Bai-Ru,Yao Duan-Zheng and Qiu Xiang-Gang.Infrared active phonon modes and ionicity of single crystal MgAl2O4[J].Chinese Physics B,2006,15(5):1090-1095. |
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| Authors: | Bi Cong-Zhi Ma Ji-Yun Yan Jun Fang Xu Zhao Bai-Ru Yao Duan-Zheng and Qiu Xiang-Gang |
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| Institution: | Department of Physics, Wuhan University, Wuhan 430072, China; Department of Physics, Wuhan University, Wuhan 430072, China;National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China; National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China |
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| Abstract: | Near-normal incident infrared reflectivity spectra of (100) MgAl2O4 spinel single crystal have been measured at different temperatures in the
frequency region between 50 and 6000cm-1. Eight infrared-active
phonon modes are identified, which are fitted with the factorized form of
the dielectric function. The dielectric property and optical conductivity of
the MgAl2O4 crystal are analysed. From TO/LO splitting, the
effective Szigeti charges and Born effective charges at different
temperatures are calculated for studying the ionicity and the effect of
polarization. Based on the relationship between the (LO--TO)1 splitting,
which represents the transverse and longitudinal frequencies splitting of
the highest energy phonon band in the reflectivity spectrum, and the
ionic-covalent parameter, the four main phonon modes are assigned.
MgAl2O4can be considered as a pure ionic crystal and its optical
characters do not change with decreasing temperature, so it may be used as a
suitable substrate for high-Tc superconducting thin films. |
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| Keywords: | MgAl2O4 single crystal phonon dielectric function effective charges |
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