Carrier Type Reversal in Pb sub x Ge sub 42-x Se58 and Pb20Ge sub y Se sub 80-y Glasses Exhibited in Thermal Diffusivity Measurements
INDIAN INST OF SCIENCE BANGALORE
Pagination or Media Count:
Bulk PbxGe42-xSe58x0, 2.5, 5,7.5, 9, 10 15 at. and Pb20GeySe80-y y 17, 19, 21, 23 and 25 at. homogeneous glasses have been prepared by melt quenching. The thermal diffusivity has been measured by the photoacoustic technique using a laboratory built non-resonant photoacoustic cell. The composition dependence of thermal diffusivity shows an anomalous behavior at x9 at of Pb in PbxGe42-xSe58 and y21 at of Ge in Pb20GeySe80-yglasses, the composition at which a p-to n- conduction transition generally occurs. The reported electrical conductivity and optical band gap measurements are used to explain the minimum thermal diffusivity value obtained at the transition threshold in these glasses. These results have been explained with the Kolobov model on the basis of modification of the charged defect states due to the addition of metallic elements.
- Ceramics, Refractories and Glass