(Ge2S8)100-xTex Chalcogenide Glasses: Physico-Mechanical Study for NIR Optical Devices

Abstract

To better understand the variations in physical, mechanical, and electrical properties, (Ge₂S₈)_100-xTe_x chalcogenide glasses have been synthesized. These glasses encompass a composition range of 0 ≤ x ≤ 12. The mechanical properties have been studied by determining the longitudinal (ν_L) and transverse (ν_T) ultrasonic velocities. A network structure evaluation with composition has been performed via parameters like coordination number (<N_r>), crosslinking density (D_CL), glass transition temperature (T_g), etc. Also, the elastic parameters trend values have been associated with the decrease in the cohesive energy value of the system. An overall physical analysis of the Ge-S-Te systems reveals that the system’s rigidity and the cross-linking density are decreasing. Within the temperature range of 300 to 420 K, the temperature dependency of the dark conductivity and photoconductivity has been investigated. The intensity-dependent photoconductivity is governed by a power law, with intensity (I_ph = G^δ) with δ lying between 0.5 and 1. The photosensitivity values reveal that the glassy system may be suitable for applications in optoelectronic devices. A correlation among the parameters has been established by calculating elastic parameters and conductivity measurements and evaluating the network structure theoretically. The present efforts clarify the composition-structure dependence and relationship in the Ge-S-Te glass series.