Evidence for self-organization processes in PbTe-Bi₂Te₃ semiconductor solid solutions

Abstract

Abstract

Self-organization processes in PbTe-Bi2Te3 semiconductor solid solutions and thermoelectric properties

“…The fact that charge carrier concentration ceases to change starting from x ~ 3.0, although the solubility limit has not been reached, indicates that the above suggested ideal scheme of substitution is realized in the composition range x = 3.0 -5.0 and the introduced impurity Bi 2 Te 3 is not electrically active. We believe that this fact supports our suggestion as to the formation of a cluster structure of solid solution, when in solid solution neutral complexes of Bi 2 Te 3 or a ternary compound are present [9,12].…”

“…These processes can include: 1) the formation of 9 th European Conference on Thermoelectrics a superstructure on the basis of the host material structure; 2) a short-range ordering within one or several coordination spheres in the host material structure; 3) the formation of clusters with a structure different from that of the host material. In [12] we estimated possible compositions at which long-range ordering occurs in this system. A simple calculation shows that the formation of a superstructure with a fcc-lattice of impurity Bi atoms is possible at x a 0.8 and at x a 2.0.…”

“…Introducing Bi one can obtain electron concentrations ensuring maximum values of ZT [7,8]. Earlier, it was established that ultimate solubility of Bi 2 Te 3 in PbTe corresponds to x~5, and under introduction ~0.1 at.% Bi in the stoichiometric p-PbTe, an inversion of the conductivity sign occurs [9][10][11][12]. In the PbTe-Bi 2 Te 3 system, five ternary compounds having tetradymite-like structures with octahedral voids occupied by Pb and Bi atoms were detected [11].…”

“…In the PbTe-Bi 2 Te 3 system, five ternary compounds having tetradymite-like structures with octahedral voids occupied by Pb and Bi atoms were detected [11]. In [12], we reported the anomalous decrease in the X-ray diffraction line width and microhardness in the ranges x ~ 0.5-1.5 and x~3-4, and these peculiarities in the isotherms of the properties were attributed to the percolation effects and complex formation processes in the solid solution.…”

Concentration anomalies of the thermal conductivity in PbTe-PbSe semiconductor solid solutions

“…The sharp growth of λ p in the critical region where there is a simultaneous increase in the charge carrier mobility and consequently we can expect an increase in crystalline order. A simple calculation shows that the composition of ∼1.0 mol% PbSe is optimal for the formation of an ordered impurity atom distribution over the sites of a primitive cubic lattice with a unit cell parameter of a = 3 a 0 , whereas at ∼1.6 mol% PbSe, the formation of a superstructure with a fcc‐lattice of impurity atoms with a unit cell parameter of a = 4 a 0 becomes probable.…”