论文标题
第一原理电子结构，声子特性，晶格导热率和FEVSB绩效图的预测
First-principles electronic structure, phonon properties, lattice thermal conductivity and prediction of figure of merit of FeVSb half-Heusler
论文作者
论文摘要
在这项工作中，我们使用FP-LAPW方法和包括自旋轨道耦合的扫描方法研究了有希望的热电feVSB的电子结构。使用获得的电子结构和运输计算，我们尝试解决FEVSB样品的实验性Seebeck系数$ S $。实验和计算出的$ S $之间的良好协议表明，乐队差距可能为$ \ sim $ 0.7 ev。这是由获得$ \ sim $ 0.7 ev的MBJ带隙支持的。此外，我们研究和报告声子分散，状态的密度和热力学特性。非分析项校正还包括远距离库仑相互作用对声子频率的影响。在准谐波近似下，计算了最高1200 K的热膨胀行为。使用第一原则的Anharmonic声子计算，考虑到声子 - phonon的相互作用，在单模弛豫时间近似下获得了FEVSB的晶格导热率$κ_{pH} $。在300 K时，计算出的$κ_{ph} $为$ \ sim $ 18.6 w $ m^{ - 1} k^{ - 1} $，与实验值相比更高。但是，计算出的$κ_{pH} $在500 K以上与实验非常吻合。通过找出最佳载体浓度来对P-Type和N型FEVSB的功绩$ ZT $的数字和效率进行预测。在1200 K时，预计P型和N型FEVSB的最大$ ZT $ $ \ sim $ 0.66和$ \ sim $ 0.44。对于P型和N型材料，$ \ sim $ 12.2 \％和$ \ sim $ 6.0 \％的最大效率分别为1200 K和300 K的热温和冷温。还讨论了通过各种元素掺杂/空位来实现N型和P型FEVSB的可能性。我们的研究有望帮助进一步探索热电材料FEVSB。
In this work, we have studied the electronic structure of a promising thermoelectric half-Heusler FeVSb using FP-LAPW method and SCAN meta-GGA including spin-orbit coupling. Using the obtained electronic structure and transport calculations we try to address the experimental Seebeck coefficient $S$ of FeVSb samples. The good agreement between the experimental and calculated $S$ suggests the band gap could be $\sim$0.7 eV. This is supported by the obtained mBJ band gap of $\sim$0.7 eV. Further, we study and report the phonon dispersion, density of states and thermodynamic properties. The effect of long range Coulomb interactions on phonon frequencies are also included by non-analytical term correction. Under quasi-harmonic approximation, the thermal expansion behaviour upto 1200 K is calculated. Using the first-principles anharmonic phonon calculations, the lattice thermal conductivity $κ_{ph}$ of FeVSb is obtained under single-mode relaxation time approximation considering the phonon-phonon interaction. At 300 K, the calculated $κ_{ph}$ is $\sim$18.6 W$m^{-1}K^{-1}$ which is higher compared to experimental value. But, above 500 K the calculated $κ_{ph}$ is in good agreement with experiment. A prediction of figure of merit $ZT$ and efficiency for p-type and n-type FeVSb is made by finding out optimal carrier concentration. At 1200 K, a maximum $ZT$ of $\sim$0.66 and $\sim$0.44 is expected for p-type and n-type FeVSb, respectively. For p-type and n-type materials, maximum efficiency of $\sim$12.2 \% and $\sim$6.0 \% are estimated for hot and cold temperature of 1200 K and 300 K, respectively. A possibility of achieving n-type and p-type FeVSb by various elemental doping/vacancy is also discussed. Our study is expected to help in further exploring the thermoelectric material FeVSb.
