Enhanced power factor and reduced thermal conductivity of a half-Heusler derivative Ti9Ni7Sn8: A bulk nanocomposite thermoelectric material

We report a half-Heusler (HH) derivative Ti9Ni7Sn8 with VEC = 17.25 to investigate the structural changes for the optimization of high thermoelectric performance. The structural analysis reveals that the resulting material is a nanocomposite of HH and full-Heusler with traces of Ti6Sn5 type-phase. Interestingly, present nanocomposite exhibits a significant decrease in thermal conductivity due to phonon scattering and improvement in the power factor due to combined effect of nanoinclusion-induced electron injection and electron scattering at interfaces, leading to a boost in the ZT value to 0.32 at 773 K, which is 60% higher than its bulk counterpart HH TiNiSn.