High temperature thermoelectric properties of TiNiSn-based half-Heusler compounds

Examining the thermal conductivity of the half-Heusler alloy TiNiSn by first-principles calculations

“…High ZT means a high power factor (PF=  2 S ) and a low  . However, due to the restriction in these coefficients, a high PF always comes with a high  in bulk materials such as half-Heusler alloys [2,3]. For a long time, reducing the  has been treating as an independent work in order to look into the possible increase in ZT.…”

“…TiNiSn-based half-Heus ler alloys as high temperature thermoelectric materials have been studied for decade [2][3][4][5][6][7]. However, its high thermal conductivity always leads to low ZT and thus greatly weaken its promising thermoelectric applications.…”

“…The increase in thermal conductivity at high temperatures is mainly due to the remarkable increase in electronic contribution. It is well-known that TiNiSn-based half-Heusler alloys always exhibit maximum ZT around 700-800 K [2,3,7]. The reason is that the maximum power factor and lowest thermal conductivity occur simultaneous ly at high temperature.…”

Introduction of resonant states and enhancement of thermoelectric properties in half-Heusler alloys

“…In the present work, it is shown that small concentrations of vanadium substituted to the group IVB metal site of Hf 0.75 Zr 0. 25 NiSn have the effect of increasing the density of states at the Fermi level, thereby augmenting the thermoelectric properties of that compound at temperatures up to 650 K. Measurements of electrical resistivity and Seebeck coefficient were carried out simultaneously from room temperature to 1100 K on a custom apparatus that has been described previously [18] and were performed during both the heating and cooling cycles. Electrical resistivity values varied less than approximately 1% from heating to cooling cycle, while Seebeck coefficient measurements of the different cycles were consistent to within 5% of one another.…”

Improving the thermoelectric performance of TiNiSn half-Heusler via incorporating submicron lamellae eutectic phase of Ti70.5Fe29.5: a new strategy for enhancing the power factor and reducing the thermal conductivity

“…In this series of materials, TiNiSn-based materials are promising thermoelectric materials with regard to elemental abundance, since they contain earth-abundant and non-toxic elements, such as Ti and Sn. [12][13][14] They are easy to prepare in large quantities using conventional solid state synthesis. The drawback associated with these materials is extremely low value of ZT (¼ (PF/k) Â T), which is primarily because of their very large thermal conductivities (k) in comparison to the other state-of-the-art TE materials.…”