Liquation phenomena in CMT melts and structural features in cadmium and mercury tellurides in a liquid phase

Abstract

The temperature dependence of Cd x Hg 1− x Te melt density of various compositions in the range upto 20 mol% CdTe has been investigated by the γ-ray attenuation method. Both the density gradient and the concentration gradient, stable in time, have been found by density measurements along the sample height. This gradient can be regarded as a new physical phenomenon in cadmium—mercury—tellurium melts (CMT). The concentration and density gradient is related to the peculiarities of intermolecular interaction nature. Success in an associated model approximation was achieved at the expense of introduction of Hg 2Te 3 associates into the molecular composition of CMT melts. As for the liquation phenomena mentioned above, they might occur at the expense of interaction between Hg 2Te 3 and CdTe associates forming [Cd 2+(Hg 2Te 4) 2−] complexes. The atomic structure of cadmium and mercury tellurides has been analyzed by molecular dynamics methods. Structural characteristics of cadmium and mercury telluride melts in the vicinity of the compound melting point have been examined using potentials of the Stillinger and Weber type. The agreement between the experimental and calculated structure factors of molten HgTe and CdTe is satisfactory. Analysis of the bond-angle distributions of atoms indicates that in 1-CdTe a covalent bonding network predominant with tetrahedral coordination takes place, while 1-HgTe possesses an inhomogeneous structure.