Du Yunzhen, Yao Yuan, Peng Kunling, Duan Jizheng, Hao Changwei, Tian Yuan, Duan Wenshan, Yang Lei, Lin Ping, Zhang Sheng
College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China.
Advanced Energy Science and Technology Guangdong Laboratory, Huizhou 516000, China.
Phys Chem Chem Phys. 2024 Sep 25;26(37):24342-24351. doi: 10.1039/d4cp02584a.
The presence of vacancy defects significantly impacts thermal properties of materials. In this research, we delve into the effects of vacancy defects on the thermal conductivity of ternary alloy BaAgBi, employing molecular dynamics simulations coupled with a deep neural network potential (NNP). Initially, we validate the precision of our NNP by comparing their predictions for energy, atomic forces, phonon dispersion curves, phonon density of states, and vacancy formation energy with density functional theory calculations, ensuring a high degree of accuracy. Our findings reveal that the reduction in thermal conductivity due to vacancies aligns with the Debye-Callaway model, with variations depending on the type of vacancy. Specifically, Ba vacancies result in the most notable decrement in thermal conductivity, attributable to their low phonon participation ratio and high lattice distortion, both factors that enhance phonon scattering. Besides, we find that the high energy barrier (∼1.66 eV) indicates that Ba vacancies hardly migrate at 300 K. This study helps us understand how vacancies affect thermal conductivity in BaAgBi and how different vacancy types affect it.
空位缺陷的存在会显著影响材料的热性能。在本研究中，我们利用分子动力学模拟结合深度神经网络势（NNP），深入探究空位缺陷对三元合金BaAgBi热导率的影响。首先，我们通过将NNP对能量、原子力、声子色散曲线、声子态密度和空位形成能的预测与密度泛函理论计算进行比较，验证了NNP的精度，确保了高度的准确性。我们的研究结果表明，由于空位导致的热导率降低与德拜 - 卡拉威模型一致，且因空位类型而异。具体而言，Ba空位导致的热导率下降最为显著，这归因于它们较低的声子参与率和较高的晶格畸变，这两个因素都会增强声子散射。此外，我们发现高能量势垒（约1.66 eV）表明Ba空位在300 K时几乎不会迁移。这项研究有助于我们理解空位如何影响BaAgBi中的热导率以及不同类型的空位如何对其产生影响。
