Han S H, Zhou Z Z, Sheng C Y, Liu J H, Wang L, Yuan H M, Liu H J
Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China.
J Phys Condens Matter. 2020 Jul 28;32(42). doi: 10.1088/1361-648X/aba2e7.
Half-Heusler compounds usually exhibit relatively higher lattice thermal conductivity that is undesirable for thermoelectric applications. Here we demonstrate by first-principles calculations and Boltzmann transport theory that the BiBaK system is an exception, which has rather low thermal conductivity as evidenced by very small phonon group velocity and relaxation time. Detailed analysis indicates that the heavy Bi and Ba atoms form a cage-like structure, inside which the light K atom rattles with larger atomic displacement parameters. In combination with its good electronic transport properties, the BiBaK shows a maximum n-typevalue of 1.9 at 900 K, which outperforms most half-Heusler thermoelectric materials.
半赫斯勒化合物通常表现出相对较高的晶格热导率，这对于热电应用来说是不理想的。在此，我们通过第一性原理计算和玻尔兹曼输运理论证明，BiBaK体系是个例外，其热导率相当低，这一点由非常小的声子群速度和弛豫时间所证实。详细分析表明，重的Bi和Ba原子形成一种笼状结构，轻的K原子在其内部以较大的原子位移参数进行振动。结合其良好的电子输运性质，BiBaK在900 K时表现出1.9的最大n型值，优于大多数半赫斯勒热电材料。
