应变对LaP和LaAs热电性能影响的第一性原理研究
First-Principles Study of Strain Effect on Thermoelectric Properties of LaP and LaAs
摘要：
稀土双金属化合物由于其独特的电子和拓扑性质而引起了人们的广泛关注。本文采用密度泛函理论（DFT）模拟研究了岩盐结构的镧镧系金属氧化物LaX（X = P，As）。我们系统地表明，一个元GGA功能结合ESTA修正可以有效地和准确地计算电子结构的精细DFT $k$网格，这是必要的收敛热电计算。我们还表明，应变工程可以有效地提高热电性能。在2%的拉伸应变和载流子浓度$n=3\times10^{20}~\textrm{cm}^{-3}$的最佳条件下，LaP在1200 K时可以达到$ZT$的品质因数值$>2$，与未应变时相比提高了90%。通过载流子掺杂和应变工程，镧铌酸盐有望成为一种新型的高温热电材料。
英文摘要：
Rare-earth monopnictides have attracted much attention due to their unusual electronic and topological properties for potential device applications. Here, we study rock-salt structured lanthanum monopnictides LaX (X = P, As) by density functional theory (DFT) simulations. We show systematically that a meta-GGA functional combined with scissor correction can efficiently and accurately compute electronic structures on a fine DFT $k$-grid, which is necessary for converging thermoelectric calculations. We also show that strain engineering can effectively improve thermoelectric performance. Under the optimal condition of 2% tensile strain and carrier concentration $n=3\times10^{20}~\textrm{cm}^{-3}$, LaP at temperature 1200 K can achieve a figure of merit $ZT$ value $>2$, which is enhanced by 90% compared to the unstrained value. With carrier doping and strain engineering, lanthanum monopnictides thereby could be promising high-temperature thermoelectric materials.
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