Photopyroelectric determination of thermal parameters across p -> n transition in Pb doped Ge-Se glasses

The thermal parameters of two series of Pb - modified Ge-Se glasses, Pb20Ge xSe80-x (x = 17 - 24) and PbyGe42-ySe58 (y = 0 - 20), which exhibit carrier type reversal from p-type to n-type at specific compositions, have been me asured simultaneously by the photopyroelectric technique. It is found that thermal diffusivity, thermal conductivity and heat capacity exhibit anomalo us variations at the compositions at which carrier type reversals are repor ted to occur in these two series of glasses. The results are explained in t erms of enhancement in electron concentration during the p - to n - type ch angeover in these materials.