Horyn A. Solid solutions based on ternary stannides and antimonides of transition and Rare Earth metals with MgAgAs and Y3Au3Sb4 structure types

In the present work the effect of substitution of the components in the ternary intermetallic compounds with MgAgAs and Y3Au3Sb4 structure types by other elements on their crystal and electronic structures and physical properties was investigated. The isothermal sections of the phase diagrams of the Ti-Co-{Sn, Sb} systems at 870/1070 К were constructed. The presence of 4 ternary compounds in these systems was confirmed. The homogeneity ranges and crystal structure of the TiCo1-xM'xSb (M' = Ni, Cu), Ti1-xScxNiSn, Zr1-xM''xNiSn (M'' = Sc, Nb, Mo), ZrNi1-xСоxSn, ZrNiSn1-xSbx, ZrCoSb1-xSnx, VFe1-xCuxSb and R3Cu3Sb4-xSnx (R = La, Ce, Pr, Nd, Sm) solid solutions were determined, their electronic transport and magnetic properties were measured. It was established that compounds with MgAgAs structure type and valence electron count (VEC) 18 el./f.u., have semiconducting properties. The changes in the VEC due to doping resulted in the gradual transition from an activated to the metallic-like conduction. Electronic structures of the 6 ternary compounds and related 4 solid solutions were calculated, and strong hybridization of the outer-shell electrons of all atoms was observed. For the ternary compounds and the substitutional solid solutions alloys with semiconducting properties a wide energy interval of low density of states, that included the Fermi level, was found. The substitution of the components in the ternary compounds resulted in the shift of the Fermi level to the conduction or valence band, and thus the n- or p-type intermetallic semiconductor was formed, respectively. The samples of the ZrCoSn1-xSbx solid solution and the TiCoSb compound were proposed as a material for the thermoelectic generators.