Top-down method to fabricate TiNi1+Sn half-Heusler alloy with high thermoelectric performance

The top-down method was used to fabricate the TiNi1+xSn half-Heusler alloy. Several knotty problems have been solved using the top-down method, including the generation of impurity phases, the visible discrepancy in the grain size of the TiNi2Sn second phase, and irregular variations in the Seebeck coefficient (S), electrical conductivity (σ), and thermal conductivity (κ) with increasing Ni content. The generation of a large number of incoherent interfaces between the half-Heusler (HH) and full-Heusler (FH) phases fabricated by the top-down method drastically improved σ and retained κ and S, thereby leading to an enhancement in the dimensionless figure of merit (ZT) by ∼19 % for the TiNi1.05Sn sample as compared to the ZT of the samples prepared by the conventional method.