Electronic and lattice thermal conductivity of $Bi_{1-x}$ $Sb_x$ and Ag-Sb-Te systems

Özet

An investigation of the electronic $(\aleph_e)$ and lattice $(\aleph_L)$ parts of the thermal conductivity for samples of $Bi_{1-x} Sb_x (0,02 < X < 0,12)$ and system of Ag-Sb-Te was carried out in the temperature interval 6-300K. Separation of $(\aleph_L)$ and $(\aleph_e)$ has been made by suppressing $(\aleph_e)$ in magnetic field. The experimental data of $(\aleph_L)$ and $(\aleph_e)$ have been compared, respectively, with Gallaway's theory and with a theory which takes into account the inelastic character of scattering. It is observed that the Lorentz number L calculated by using the experimental values of $(\aleph_e)$ and thermomagnetic coefficients is smaller than its Zommerfeld's value $L_o$ in high doping $Bi_{0.88}Sb_{0.12}. A satisfactory agreement between the theory and the experiment allows to conclude that besides the normal and U-processes in $Bi_{1-x} Sb_x$ the defects of mass also plays a considerable role in scattering. It is observed that $(\aleph_L)$ of single phase samples $Ag_{0.82}=Sb_{1.18}Te_{2.18}$ is smaller than $AgSbTe_2$ samples. It is shown that this is due to the presence of $p-Ag_2$ Te in $AgSbTe_2$ . It is established that the high concentration of intrinsic defects plays a considerable role in scattering for Ag-Sb-Te as well.