Thermal conductivity of Ge₂₅Bi₄₀Te₃₅ and Ge₂₅Bi₄₀Sb₃₅ Semi conducting in solid and liquid states

An investigation is made on the thermal conductivity for the ternary semiconducting glasses Ge₂₅ Bi₄₀ Te₃₅ and Ge₂₅ Sb₄₀ Sb₃₅ in solid and liquid states in a wide range of temperature from room temperature to near 600°C. Measurements of thermal conductivity (λ) were carried out using the concentric cylinder method which is based on the flow of heat through a cylindrical wall.

The temperature dependence of the thermal conductivity (λ) was explained by postulating different mechanism for the thermal conductivity (λ) in semiconductors. The contribution of electronic, phonon and complementary mechanisms to the heat transfer is evaluated. The thermal conductivity due to atomic motion (λ_a) is also calculated. In addition the thermoelectric Q – factor (Z) is evaluated for both investigated samples in the solid and liquid states. It was noticed that Q-Factor (Z) increases with temperature, which help to use these material in the practical application