The electronic and thermoelectric properties of bulk and [001] surfaces of half-Heusler compound TiNiSn are investigated consistently by combining the first principle electronic structure calculations and BOLTZRAP transport theory. It is found that semi-metallic behavior in the Fermi level compared with the bulk state of a compound is declined and just at Ti-Sn termination, a gap near the Fermi surface exists. Our calculations have indicated that Ti-Sn termination has a high density near the Fermi surface which is mostly due to the d orbitals of Ni atoms. Since the power factor and figure of merit depend on electrical conductivity, the decisive factor in determining the thermoelectric performance of materials is their thermal conductivity which, according to the calculations we performed, in Ti-Sn termination, with increasing temperature, the lattice thermal conductivity is decreased logarithmically. So we can conclude thin films can be better thermoelectric materials in high temperatures rather than bulk phases from the same compound. The most amount of figure of merit, which we could obtain at about 1000 K is 0.76 and 0.72 for Ti-Sn termination and bulk phase, respectively. Phase diagram calculations were performed for [001] surfaces of TiNiSn compound and stability of all terminations was investigated.

通过结合第一原理电子结构计算和BOLTZRAP输运理论，对半Heusler化合物TiNiSn的本体和[001]表面的电子和热电性质进行了一致的研究。发现与化合物的整体状态相比，在费米能级下的半金属行为下降，并且仅在Ti-Sn终止处，在费米表面附近存在间隙。我们的计算表明，Ti-Sn端子在费米表面附近具有很高的密度，这主要归因于Ni原子的d轨道。由于功率因数和品质因数取决于电导率，因此决定材料热电性能的决定性因素是其热导率，根据我们进行的计算，在Ti-Sn端接中，随着温度的升高，晶格热导率对数降低。因此我们可以得出结论，在高温下，薄膜可以是更好的热电材料，而不是同一化合物的整体相。对于Ti-Sn终止相和体相，我们在约1000 K处可获得的最大品质因数分别为0.76和0.72。对TiNiSn化合物的[001]表面进行了相图计算，并研究了所有端子的稳定性。