thermoelectric material

The DFT modeling of the TiF1+xSb solid solution revealed that composition TiFe1.375Sb with MnCu2Al structure type is more preferable than equiatomic TiFeSb which crystallizes in MgAgAs-type. At T > 873 K the formation of the two phase region containing both half-Heusler and fullHeusler phases is predicted. The composition dependence of the lattice parameter shows deviation from linearity. The calculations explain the difficulties in solid solutions formation based on TiFeSb intermetallic.

The studied TmNiSb alloy crystallizes in the MgAgAs structure type (half-Heusler phases) and according to the results of DFT+U calculations revealed the presence of bandgap (Eg = 359 meV). Spin magnetic moment of Tm atoms equals 2.16 μB confirming its Tm3+ state. Calculated elastic properties as well as Vickers hardness of TmNiSb alloy was defined semi-empirically and equals 15.98 GPa. Experimentally determined microhardness is within the range of 2.90 – 4.06 GPa with the exception of TmNiSb phase.