Carrier-type reversal in Pb–Ge–Se glasses: Photopyroelectric measurements of thermal conductivity and heat capacity

The thermal conductivity and heat capacity of Pb modified Ge–Se glasses, Pb20GexSe80−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 measured simultaneously by the photopyroelectric technique. The thermal conductivity as well as the heat capacity show anomalous variations at the compositions at which carrier-type reversals are reported to occur in these glasses. The results are explained in terms of the enhancement in electron concentration during p- to n-type changeover in these materials.