Synthesis, electrical transport, magnetic properties and electronic structure of Ti1-xScxCoSb semiconducting solid solution

Abstract

The effect of Sc doping on the electric transport, magnetic properties and electronic structure of the half-Heusler TiCoSb semiconductor was studied. Samples of the Ti1-xScxCoSb solid solution (0.005 ≤ x ≤ 0.15) were synthesized by arc-melting, annealed at 1070 K and examined by X-ray powder diffraction and scanning electron microscopy with energy-dispersive X-ray analysis. All alloys of the solid solution crystallize in the MgAgAs structure type (space group F4¯3m) and stability range reaches the Ti0.85Sc0.15CoSb composition. Electrical resistivity and Seebeck coefficient were measured in the 80–380 K temperature range. It was found that doping TiCoSb by Sc atoms results in transition from semiconducting behavior to metallic. Increasing of Sc acceptor impurity in the Ti1-xScxCoSb solid solution changes the Seebeck coefficient from negative to positive values. The mechanisms of electrical conductivity of the Ti1-xScxCoSb solid solution were analyzed and compared with the results of the electronic band structure calculations.