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arXiv 2103.11358cond-mat.mtrl-sci
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212 MAX相硼化物Zr2AB2(A = In,Tl)热机械性能增强的从头算研究

Enhanced thermo-mechanical properties of 212 MAX phase borides Zr2AB2 (A = In, Tl): an ab-initio understanding

M. A. Ali, M. M. Hossain, M. M. Uddin, A. K. M. A. Islam, S. H. Naqib

摘要:

MAX相硼化物的发现为材料科学界的研究增添了新的维度。本文对新近发现的MAX相硼化物Zr_2AB_2(A = In,Tl)进行了第一性原理研究。计算得到的晶格常数和晶胞体积与前人的研究结果一致。考察了标题化合物的动力学和机械稳定性。刚度常数,弹性模量,硬度参数,脆性和各向异性指数的基本见解。基于Mulliken布居分析和电荷密度图(CDM)解释了这些力学性能的变化。通过电子能带结构和态密度(DOS)研究了Zr_2AB_2(A = In,Tl)的电子性质,证实了Zr_2AB_2的金属性质。沿c方向的低色散能带证实了电导率的各向异性。DOS分析表明,Zr-d轨道对电导率的贡献占主导地位,In/Tl-p态在费米能级上的贡献很小。计算了德拜温度(θ D)、最小热导率(Kmin)、Gruneisen参数和熔化温度(Tm)。与Zr_2AC(A = In,Tl)相比,Zr_2AB_2(A = In,Tl)具有更高的θ-D和Tm值以及更低的Kmin值。此外,还计算了比热容、热膨胀系数和不同的热力学势函数。的光学常数进行了研究,以揭示其可能的应用目的的相关性。反射率光谱揭示了Zr_2AB_2(A = In,Tl)作为覆盖材料减少太阳加热的适用性。将所研究的Zr_2AB_2(A = In,Tl)的物理性质与其他相关的212和211 MAX相纳米层压材料的物理性质进行了比较。

英文摘要:

The discovery of MAX phase borides has added a new dimension for research in the materials science community. In this paper, a first-principles study of the newly known MAX phase borides Zr2AB2 (A = In, Tl) has been carried out. The estimated lattice constants and volumes of the unit cell are found to be consistent with previous study. The dynamical and mechanical stability of the titled compounds have been checked. Fundamental insights into the stiffness constants, elastic moduli, hardness parameters, brittleness and anisotropy indices are presented. The Variation of these mechanical properties was explained based on the Mulliken population analysis and charge density mapping (CDM). The electronic properties have been dealt with by considering electronic band structure and density of states (DOS) which confirmed the metallic nature of Zr2AB2 (A = In, Tl). The lowly dispersive energy bands along the c-direction confirmed anisotropy in conductivity. The analysis of DOS revealed the dominant contribution from Zr-d orbitals to the conductivity with a small contribution from the In/Tl-p states contributing at the Fermi level. The Debye temperature (Theta-D), minimum thermal conductivity (Kmin), Gruneisen parameter and melting temperature (Tm) have been calculated. The higher values of Theta-D and Tm, and lower value of Kmin for Zr2AB2 (A = In, Tl) compared to those of Zr2AC (A = In, Tl). Besides, the specific heat capacities, thermal expansion coefficient, and different thermodynamic potential functions have been calculated. The optical constants have been studied to reveal their possible relevance for application purposes. The reflectivity spectra revealed the applicability of Zr2AB2 (A = In, Tl) as cover materials to diminish the solar heating. The studied physical properties of Zr2AB2 (A = In, Tl) are compared with those of other relevant 212 and 211 MAX phase nanolaminates.

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