论文标题
半赫斯勒化合物Bibak的高热电性能具有本质上较低的晶格导热率
High thermoelectric performance of half-Heusler compound BiBaK with intrinsically low lattice thermal conductivity
论文作者
论文摘要
半赫斯勒化合物通常表现出相对较高的晶格导热率，这对于热电应用是不希望的。在这里，我们通过第一原理的计算和玻尔兹曼传输理论证明了Bibak系统是一个例外，它的导热率相当低，这可以通过非常小的声子组速度和松弛时间来证明。详细的分析表明，重的BI和BA原子形成类似笼子的结构，在该结构中，较大的原子位移参数的光原子嘎嘎作响。结合其良好的电子传输特性，Bibak在900 K时表现出最大的N型ZT值1.9，其表现优于最大的Heusler热电材料。
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-type ZT value of 1.9 at 900 K, which outperforms most half-Heusler thermoelectric materials.
