Thermal, mechanical, electrical and thermoelectric properties of Bi–As–Se glasses

The current study focuses on the impact of As addition on the thermal, mechanical, electrical and thermoelectric properties of ternary ${\text{Bi}}_{0.02}{\text{As}}_{\text{x}}{\text{Se}}_{0.98-\text{x}}$ ($0.02\le x\le 0.08$) glasses. Different elastic moduli such as the micro-hardness (H), Young's modulus (Y), bulk modulus (K), Poisson's ratio (Pr) and shear modulus (S) as well as Debye temperature (TD) for the studied glasses were estimated by using the measured values of the ultrasonic speeds (transfer, v_l, and shear, v_s) and density (ρ). Moreover, the measured values of the dc electrical conductivity (σ_dc) and thermoelectric power (S_thermo) were used to estimate the activation energies for the electrical (ΔE_dc) and for thermoelectric (ΔE_thermo) conductions, respectively. It was found that σ_dc increases, whereas S_thermo, ΔE_dc and ΔE_thermo decrease with increasing the As content for the ${\text{Bi}}_{0.02}{\text{As}}_{\text{x}}{\text{Se}}_{0.98-\text{x}}$ ($0.02\le x\le 0.08$) thin films. In addition, replacement of Se with As atoms results in an increase in the average coordination number (CN), cross-linking density (Cd), cohesive energy (CE), ρ, H, Y, K, S and TD, whereas the molar volume (V_m), Pr and the homopolar Se–Se bonds decreased. Both of Y and K as well as ΔE_dc are correlated with the glass transition temperature (T_g).