Abstract
This paper reports the experimentally measured thermal and electrical conductivities from which the Lorenz numbers as functions of temperature were derived for the solids and melts of elemental Te and samples of Hg1−xCdxTe of x = 0, 0.1, and 0.2. The structural changes in the vicinity of the solid–liquid phase transition of elemental Te and various Hg1−xCdxTe solid solutions were assessed by closely examining these experimental properties and the derived Lorenz numbers. The values of Lorenz numbers for the solids of these samples were higher than the value of L0, i.e., the Lorenz number for the free-electron gas derived by Sommerfeld [Naturwissenschaften 15, 825 (1927)], implying the characteristics of a non-degenerate semiconductor. With the increasing value of x, or the larger bandgap, the materials become more non-degenerate with larger deviation from L0. As the solids started to melt, the measured values of the Lorenz number for all samples started to decrease and eventually reached and maintained at values close to L0 at higher temperatures. The trend of the Lorenz number indicates the transition from a non-degenerate semiconductor of the solid samples to a metal or degenerate semiconductor when the temperatures of the samples reached above their liquidus temperatures.
Highlights
In the 1850s, Wiedemann and Franz reported that the ratio of thermal conductivity, κ, to electrical conductivity, σ, for different metals has the same value at room temperature
PUBLISHED RESULTS ON THERMAL AND ELECTRICAL CONDUCTIVITY
The melting temperatures for Te and HgTe were marked, and the ranges between the solidus and liquidus temperatures41 for the pseudo-binary samples Hg0.9Cd0.1Te and Hg0.8Cd0.2Te are shown as bands in their respective colors
Summary
% Te is 0.4894 for HgTe, 0.9465 for CdTe, and 0.9380 for ZnTe. From the calculated results of the associated solution model for the three binary systems, the mole fraction of the binary species in the liquid phase at its respective melting point with 50 at. This paper reports the studies of the experimentally measured thermal and electrical conductivities and the derived Lorenz numbers as functions of temperature for the solids and melts of elemental Te and samples of Hg1−xCdxTe of x = 0, 0.1, and 0.2. With the bandgap energy covering from medium to longwavelength infrared (IR) spectra, the solid solutions of the semimetal HgTe and the wide bandgap semiconductor of CdTe (bandgap of 1.65 eV) provide the materials for advanced detectors of different IR wavelengths Because of their high vapor pressure and extreme toxicity, the thermophysical properties of the melts of Hg-based II–VI compound semiconductors have only been studied lately.. Because of their high vapor pressure and extreme toxicity, the thermophysical properties of the melts of Hg-based II–VI compound semiconductors have only been studied lately. With a closer examination of these results, the structural changes in the vicinity of the solid–liquid phase transition of elemental Te and various Hg1−xCdxTe solid solutions, as well as the structural evolutions during the heating of the melts, were assessed by the thermophysical properties and the Lorenz numbers derived from them
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