Structural and electronic properties of liquid K-Te alloys

Ab initio MD studies of the structural and electronic properties of K-Te alloys at three different stoichiometric compositions are presented. The tellurium-rich mixture K0.12Te0.88 is entirely determined by the Te atoms, with a structure and electronic properties that are very similar to those of pure liquid Te. The properties of equiatomic KTe at 770 K are determined by the strong iono-covalent bonding, but the order of the crystalline phase, consisting of Te22- dumbbells in a matrix of K cations, is blurred to a very high degree. The strong coupling of the potassium cations to the Te system is also shown by the diffusion constant. In the octet compound K2Te at 1300 K we found that the ionic character of the solid salt is preserved in the liquid. The electronic properties of both liquid mixtures, although modified by thermal disorder, show some similarities to the crystalline phases, especially a deep minimum at the Fermi edge, confirming the low conductivity values that are experimentally measured. Π2002 Published by Elsevier Science B.V.