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 Ti 1- x Sc x CoSb 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 F 4 ¯ 3 m ) and stability range reaches the Ti 0.85 Sc 0.15 CoSb 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 Ti 1- x Sc x CoSb solid solution changes the Seebeck coefficient from negative to positive values. The mechanisms of electrical conductivity of the Ti 1- x Sc x CoSb solid solution were analyzed and compared with the results of the electronic band structure calculations.