Experimental and theoretical investigation of the Y–Ni–Sb and Tm–Ni–Sb systems

Interaction of Yttrium and Thulium with Nickel and Antimony was studied at 870 K in the whole concentration range based on XRD and EPM analyses. Four ternary compounds are realized in the Y–Ni–Sb system: Y5Ni2Sb (Mo5SiB2-type), Y5NixSb3-x (Yb5Sb3-type), YNiSb (MgAgAs-type), and Y3Ni6Sb5 (Y3Ni6Sb5-type). At 870 K the Tm–Ni–Sb system is characterized by the formation of two ternary antimonides: Tm5Ni2Sb (Mo5SiB2-type) and TmNiSb (MgAgAs-type). Temperature dependencies of the electrical resistivity and Seebeck coefficient of the YNiSb and TmNiSb half-Heusler compounds were measured in the temperature range 80–380 K. Both compounds behave as doped and compensated semiconductors. The DFT calculations were performed for the ordered and disordered models of YNiSb to explain the homogeneity region and transport properties. •Phase diagrams of the Y–Ni–Sb and Tm–Ni–Sb systems constructed at 870 K.•A limited homogeneity region of YNiSb observed.•Both YNiSb and TmNiSb show semiconducting behavior with a p-type of conductivity.