Bi_2-xSb_xTe_3-ySe_y系の性質 (I)

抄録

The electrical properties of Bi_2-xSb_xTe_3-ySe_y with stoichiometric composition of metal components (Bi and Sb) and metalloid components (Te and Se) are investigated. These materials are prepared by melting, quenching and annealing. It is found that the crossover points of the thermoelectric power from p-type to n-type coincide with the electrical conductivity minima, and value of y corresponding to these intrinsic characteristics increases with increasing x. X-ray observations disclosed a continuous solid solution with rhombohedral structure except in the region where the composition is close to Sb₂Se₃.
In the latter region, curves of electrical conductivity and thermoelectric power show discontinuities and admixture phases of rhombohedral and orthorhombic structures appear. Based on a model of chemical bonding in compounds of the type of A₂^VB₃^VI, explanation is given to the observed results.