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Strain engineered thermodynamic stability, electronic and thermoelectric characteristics of TiB2 and ZrB2 monolayers
Physica E: Low-dimensional Systems and Nanostructures ( IF 3.3 ) Pub Date : 2022-09-03 , DOI: 10.1016/j.physe.2022.115477
Shubham Tyagi , Rajneesh Chaurasiya , Nirpendra Singh , Ambesh Dixit

The thermodynamic stability, electronic, and thermoelectric properties of TiB2 and ZrB2 are computed using density functional and Boltzmann transport theory. The phonon band dispersion of ZrB2 monolayer exhibits dynamic instability with the presence of imaginary frequency. The small direct bandgap is noticed for these monolayers. More interestingly, the biaxial strain improves the dynamic stability of ZrB2 monolayer. In addition, the electronic properties are not changing significantly for the considered monolayers. The strain modulated Seebeck coefficient, electrical conductivity, and electronic thermal conductivity are investigated to understand the thermoelectric properties. The Seebeck coefficient is reducing while electrical conductivity and electronic thermal conductivity are improving with increasing temperature. The Seebeck coefficient is decreasing with increasing the biaxial tensile strain. Moreover, the electrical conductivity and electronic thermal conductivity values are increasing with the increasing strain. Further, a very large lattice thermal conductivity is observed for TiB2 monolayer as compared to ZrB2 monolayer. Thus, strain can be used to enhance the dynamic stability and modulate the thermoelectric properties of such systems and TiB2 monolayer may be a potential low temperature efficient thermoelectric material because of its small bandgap and high thermal conductivity at low temperatures.



中文翻译:

TiB2 和 ZrB2 单层的应变工程热力学稳定性、电子和热电特性

使用密度泛函和玻尔兹曼输运理论计算TiB 2和 ZrB 2的热力学稳定性、电子和热电特性。ZrB 2单层的声子能带色散在虚频的存在下表现出动态不稳定性。对于这些单层,注意到小的直接带隙。更有趣的是,双轴应变提高了ZrB 2单层的动态稳定性。此外,所考虑的单层的电子特性没有显着变化。应变调制塞贝克系数、电导率和电子热导率进行研究以了解热电特性。塞贝克系数正在降低,而电导率和电子热导率随着温度的升高而提高。塞贝克系数随着双轴拉伸应变的增加而减小。此外,电导率和电子热导率值随着应变的增加而增加。此外,与ZrB 2单层相比,TiB 2单层观察到非常大的晶格热导率。因此,应变可用于增强动态稳定性并调节此类系统和 TiB 2的热电性能单层由于其带隙小和低温下的高热导率,可能是一种潜在的低温高效热电材料。

更新日期:2022-09-03
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