First Principles Investigation of Anomalous Pressure-Dependent Thermal Conductivity of Chalcopyrites
First Principles Investigation of Anomalous Pressure-Dependent Thermal Conductivity of Chalcopyrites
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DOI：
10.3390/ma12213491
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发表时间：
2019-10
期刊：
影响因子：
3.4
通讯作者：
Loay Elalfy;D. Music;Ming Hu
中科院分区：
文献类型：
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作者：
Loay Elalfy;D. Music;Ming Hu
采用声子玻尔兹曼输运方程（BTE）计算方法，研究了300 K下压缩对CuGaS 2、CuInS 2、CuInTe 2和AgInTe 2黄铜矿（空间群I-42 d）热导率的影响.通过求解具有谐波和三阶原子间力常数的BTE来评估热导率。CuGaS 2的热导率随压力增加而增加，这是一种常见的行为。其他三种化合物存在显着差异。CuInTe 2和AgInTe 2在压力增加时表现出热导率的下降，这是反常的。AgInTe 2在2.6 GPa下达到0.2 W·m-1·K-1的非常低的热导率，这对于许多能量器件（例如热电器件）是有益的。CuInS 2是一种中间情况。基于声子色散数据，CuInTe 2和AgInTe 2的声学模式的声子频率随着压力的增加而降低，从而驱动异常，而CuGaS 2没有显着的压力效应。这导致CuInTe 2和AgInTe 2的负Grüneisen参数，声子弛豫时间减少，热导率降低。这种软化的压缩后的声学模式被认为是由于黄铜矿积木的旋转运动，而不是压缩振荡。根据格吕奈森振动理论，负的格吕奈森参数和反常的声子行为在较低温度下产生负的热膨胀系数。
The effect of compression on the thermal conductivity of CuGaS2, CuInS2, CuInTe2, and AgInTe2 chalcopyrites (space group I-42d) was studied at 300 K using phonon Boltzmann transport equation (BTE) calculations. The thermal conductivity was evaluated by solving the BTE with harmonic and third-order interatomic force constants. The thermal conductivity of CuGaS2 increases with pressure, which is a common behavior. Striking differences occur for the other three compounds. CuInTe2 and AgInTe2 exhibit a drop in the thermal conductivity upon increasing pressure, which is anomalous. AgInTe2 reaches a very low thermal conductivity of 0.2 W·m−1·K−1 at 2.6 GPa, being beneficial for many energy devices, such as thermoelectrics. CuInS2 is an intermediate case. Based on the phonon dispersion data, the phonon frequencies of the acoustic modes for CuInTe2 and AgInTe2 decrease with increasing pressure, thereby driving the anomaly, while there is no significant pressure effect for CuGaS2. This leads to the negative Grüneisen parameter for CuInTe2 and AgInTe2, a decreased phonon relaxation time, and a decreased thermal conductivity. This softening of the acoustic modes upon compression is suggested to be due to a rotational motion of the chalcopyrite building blocks rather than a compressive oscillation. The negative Grüneisen parameters and the anomalous phonon behavior yield a negative thermal expansion coefficient at lower temperatures, based on the Grüneisen vibrational theory.