Abstract Far-infrared reflectivity spectra of bismuth germanium oxide (Bi12GeO20) single crystals are measured from room temperature down to 10 K. All the reflectivity spectra are fitted to a complex dielectric function $\varepsilon(\omega)$ in the factorised form. Phonon modes at low frequency are found to develop upon decreasing temperature and gain considerable spectrum weight below 150 K. The temperature-dependent static dielectric constants are obtained from the Lyddane--Sachs--Teller relation based on the obtained oscillator parameters. The dielectric constants are found to increase upon decreasing temperature, which is attributed to the charge transfer among the ions in the unit cell with the temperature varying.
Received: 27 April 2009
Revised: 21 May 2009
Accepted manuscript online:
Fund: Project supported by the National
Natural Science Foundation of China (Grant No 10674168) and Ministry
of Science and Technology,
China (Grant Nos 2006CB601006 and 2009CB930701).
Cite this article:
Muhammad Kamran, Dai Yao-Min(戴耀民), Ma Ji-Yun(马继云), Li Bo-Hong(李博宏), He Shi-Kun(何世坤), Zhang Wei-Jun(张伟君), Zheng Xiao-Rui(郑小睿), and Qiu Xiang-Gang(邱祥冈) Temperature-dependent far-infrared properties of Bi12GeO20 single crystal 2009 Chin. Phys. B 18 4425
Altmetric calculates a score based on the online attention an article receives. Each coloured thread in the circle represents a different type of online attention. The number in the centre is the Altmetric score. Social media and mainstream news media are the main sources that calculate the score. Reference managers such as Mendeley are also tracked but do not contribute to the score. Older articles often score higher because they have had more time to get noticed. To account for this, Altmetric has included the context data for other articles of a similar age.