富镁Laves相LaMg2中金属键驱动的弹性软度与光学响应
Metallic Bonding-Driven Elastic Softness and Optical Response in the Mg-Rich Laves-Phase LaMg2
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中文总结 AI 辅助
本研究通过第一性原理计算证实富镁Laves相LaMg2具有本征稳定性、弹性软度、延性及金属光学特性，有望用于电磁屏蔽等轻质结构材料领域。
中文摘要 AI 辅助
本文基于密度泛函理论，对立方C15型Laves相金属间化合物LaMg2的结构、电子、力学及光学性质开展了系统的第一性原理研究。计算得到的弹性常数满足立方晶体的力学稳定性判据，证实了C15相的本征稳定性。LaMg2的体积模量、剪切模量和杨氏模量相对较低，与过渡金属基Laves相相比，其可压缩性更高、弹性软度更显著。方向相关的弹性分析表明，杨氏模量、剪切模量和泊松比呈现中等各向异性，而线性可压缩性几乎各向同性，这与高晶体学对称性一致。Pugh比和泊松比的结果支持LaMg2具有延性，表明其抗脆性破坏能力较强，且金属键占主导地位。电子结构计算确认LaMg2具有金属特性，费米能级处存在有限的态密度，主要源自La-5d态，同时呈现出金属相互作用特有的离域电荷密度。光学响应进一步通过高反射率、低光子能量下的强光导率以及紫外区的显著吸收，反映了其金属特性。兼具力学柔顺性、延性和金属光学响应的LaMg2，有望成为轻质金属间化合物材料，适用于对结构稳定性、损伤容限及高效电磁屏蔽或反射部件有需求的应用场景。
英文摘要
A systematic first-principles investigation of the structural, electronic, mechanical, and optical properties of the cubic C15 Laves-phase intermetallic compound LaMg2 is performed within density functional theory. The calculated elastic constants satisfy the mechanical stability criteria for cubic crystals, confirming the intrinsic stability of the C15 phase. LaMg2 exhibits relatively low bulk, shear, and Young's moduli, indicating enhanced compressibility and elastic softness compared with transition-metal-based Laves phases. Direction-dependent elastic analysis reveals moderate anisotropy in Young's modulus, shear modulus, and Poisson's ratio, whereas linear compressibility remains nearly isotropic, consistent with the high crystallographic symmetry. The ductile nature of LaMg2 is supported by Pugh's ratio and Poisson's ratio, suggesting resistance to brittle failure and the dominance of metallic bonding. Electronic structure calculations confirm metallic behavior with a finite density of states at the Fermi level, primarily originating from La-5d states, accompanied by delocalized charge density characteristic of metallic interactions. The optical response further reflects the metallic nature through high reflectivity, strong optical conductivity at low photon energies, and pronounced absorption in the ultraviolet region. The combination of mechanical compliance, ductility, and metallic optical response highlights LaMg2 as a promising lightweight intermetallic material for applications requiring structural stability, damage tolerance, and efficient electromagnetic shielding or reflective components.
