Electronic Structures of Bismuth Telluride by Non-relativistic Calculation and Thermoelectric Properties

Bismuth tellurides have been studied for investigating their electronic structures by using the discrete variational Xα method. The systems of not only Bi_2Te_3 but also the Se or Sb substituted-Bi_2Te_3 were calculated with setting three kinds of cluster corresponding to the base structure of Bi_2Te_3; cluster C-1 : Bi_7Te_6,cluster C-2 : Bi_6Te_7 and cluster C-3 : Bi_3Te_. Major conditions for the calculation are non-relativistic, non-spin and the crystal group of C3V. The cleavage and bond strength of the Bi_2Te_3 structure were cleared through the calculations. The Se substituted-Bi_2Te_3 led to offsetting ionic structure of Bi_2Te_3 of the base material and to the n-type thermoelectricity. Furthermore, the substitution with Sb atom caused the positive charge with rather covalent bonding nature than that in Bi_2Te_3.Bismuth tellurides have been studied for investigating their electronic structures by using the discrete variational Xα method. The systems of not only Bi_2Te_3 but also the Se or Sb substituted-Bi_2Te_3 were calculated with setting three kinds of cluster corresponding to the base structure of Bi_2Te_3; cluster C-1 : Bi_7Te_6,cluster C-2 : Bi_6Te_7 and cluster C-3 : Bi_3Te_. Major conditions for the calculation are non-relativistic, non-spin and the crystal group of C3V. The cleavage and bond strength of the Bi_2Te_3 structure were cleared through the calculations. The Se substituted-Bi_2Te_3 led to offsetting ionic structure of Bi_2Te_3 of the base material and to the n-type thermoelectricity. Furthermore, the substitution with Sb atom caused the positive charge with rather covalent bonding nature than that in Bi_2Te_3