Transition thresholds in Ge-As-Se chalcogenide glasses

报告人：王荣平

报告时间：2013年12月17日 下午02:30

报告地点：物理与电子工程学院四楼重点实验室报告厅

主办单位：江苏师范大学物理与电子工程学院 科技处

报告摘要：

Glass transition, density, raman spectroscopy and elastic constants of Ge_xAs_ySe_1-x-y chalcogenide glasses with mean coordination numbers (MCN) from 2.2 to 2.94 were investegated to understand the transition thresholds in the glasses. The main results include: (1) Whilst Raman features below 150 cm^-1, which are only sensitive to the network connectivity, were found to follow the isocoordinate rule for chalcogenide glasses, the dependence of the spectral evolution at high wavenumber exhibits two transition-like features. Merging of the 225 and 250 cm^-1 modes at MCN=2.5 is a symbol of the extinction of free Se. Additionally, the two new modes around 280-290 and 170 cm^-1 at MCN>2.7 come from the defect modes of ethanelike Ge₂Se_6/2. The increase of the scattering from these defects is an important factor leading to an enhanced optical loss in the glasses with high MCN. (2) For the first time we simultaneously observed two elastic transition thresholds at MCN≈2.45 and at 2.65, which are closely correlated with the evolution of the glass microstructure. The elastic moduli of two groups of the samples with same MCN but different compositions suggest that the chemical compositions could have an effect on determination of the elastic transition thresholds. All these results confirm that there are two transitions in Ge_xAs_ySe_1-x-y located at MCN = 2.45 and 2.65.

报告人简介：

王荣平, 1969年生，2000年在中科院物理所获得物理学博士学位，目前是澳大利亚激光物理中心研究员。主要从事红外硫系玻璃的结构、光敏性、新型光学通讯器件， 脉冲激光沉积晶态氧化物薄膜等方面的基础和应用研究，在国际知名 期刊上发表了110多篇学术论文，被引用1800多次，发表了玻璃科学领域专著1章。是多个国际学术期刊的特约审稿人，是中国自然基金委海外专家和澳大利亚ARC的评审专家。在国际会议上做过十多次邀请报告，多次应邀给国内的高校、研究所（昆明物理所等）、公司（西安光电集团等）提供咨询和技术指导，培养了7名博士生。