Yuan Bing, Chen Hao, Sen Sabyasachi
Department of Materials Science & Engineering, University of California at Davis, Davis, California 95616, United States.
J Phys Chem B. 2022 Feb 3;126(4):946-952. doi: 10.1021/acs.jpcb.1c08836. Epub 2022 Jan 21.
The structural evolution of GeSe glass during aging is studied using Raman spectroscopy and density relaxation measurements. The Raman spectra indicate volume- and entropy-driven changes in the relative concentrations of the corner-sharing (CS) and edge-sharing (ES) GeSe tetrahedra and in the degree of chemical order of the tetrahedral network during aging at 65 °C below the nominal glass transition temperature. The attendant structural changes involve a progressive increase in the CS:ES ratio and in the chemical order that can be expressed in the form of a reaction Ge-Ge + Se-Se → 2 Ge-Se, which shifts to the right, with lowering of fictive temperature. The isothermal relaxation of both the structure and density during aging displays rather similar stretched exponential kinetics with a stretching exponent β ∼0.54 and an average relaxation time of ∼13.5 h. high-temperature Raman spectroscopic measurements indicate that structural relaxation does not affect the anharmonicity of the vibrational potential wells in the energy landscape of GeSe glass.
利用拉曼光谱和密度弛豫测量研究了GeSe玻璃在老化过程中的结构演变。拉曼光谱表明，在低于标称玻璃化转变温度65℃的条件下老化时，角共享（CS）和边共享（ES）GeSe四面体的相对浓度以及四面体网络的化学有序度发生了体积和熵驱动的变化。伴随的结构变化包括CS:ES比和化学有序度的逐渐增加，这可以用反应Ge-Ge + Se-Se → 2 Ge-Se的形式表示，随着虚构温度的降低，该反应向右移动。老化过程中结构和密度的等温弛豫表现出相当相似的拉伸指数动力学，拉伸指数β约为0.54，平均弛豫时间约为13.5小时。高温拉曼光谱测量表明，结构弛豫不会影响GeSe玻璃能量景观中振动势阱的非谐性。
