Temperature-dependent far-infrared properties of Bi12 GeO20 single crystal

• 来源期刊: 中国物理B（英文版）
• 关键词: infrared reflectivity dielectric properties phonon
• 年，卷（期）: 2009,（10）
• 页码范围: 4425-4429
• 页数: 5页
• 语种: 英文

摘要

Far-infrared reflectivity spectra of bismuth germanium oxide(Bil2GeO20)single crystals are measured from roomtemperature down to 10 K.All the reflectivity spectra are fitted to a complex dielectric function ε([w]) in the factorisedform.Phonon modes at low frequency are found to develop upon decreasing temperature and gain considerable spectrumweight below 150 K.The temperature dependent static dielectric constants are obtained from the Lyddane-SachTellerrelation based on the obtained oscillator parameters.The dielectric constants are found to increase upon decreasingtemperature.which is attributed to the charge transfer among the ious in the unit cell with the temperature varying.