arXiv subjects

Meiguang Zhang

Publications and source records attributed to Meiguang Zhang.

5 recordsLinked to original sources

arXiv2026

Design of a 60.8 K superconducting hydride LiMgZr2H12 at ambient pressure via Lithium doping

High-pressure hydrogen-rich compounds have long been regarded as promising room-temperature superconductor candidates; however, their practical applications are limited by their reliance on extreme compression. This study explores hydrogen-rich superconductors that may be stable at ambient pressures. Inspired by recent investigations of the MgZrH2n family, the LiMgZr2H12 structure with a Pmmm symmetry was constructed, and its thermodynamic, mechanical, and dynamical stability were evaluated using first-principles calculations. Electron-phonon coupling (EPC) analysis suggests that LiMgZr2H12 reaches a superconducting critical temperature (Tc) of 60.8 K at ambient pressure. Compared with MgZrH6, Li doping significantly increases the contribution of hydrogen atoms to the electron density of states near the Fermi level (EF) and enhances the EPC constant of the LiMgZr2H12 structure. LiMgZr2H12 exhibits a superconducting figure of merit of 1.56, which is significantly greater than that of MgZrH6, demonstrating its outstanding potential for practical applications. This work guides ambient-pressure design of high-Tc hydrides.

cond-mat.supr-con↗

arXiv2025

First-Principles Study of High-Temperature Superconductivity in X2MH6 Compounds under 20 GPa

Research on high-temperature superconductors has primarily focused on hydrogen-rich compounds, however, the need for extreme pressures limits their practical applications. The X2MH6-type structure Mg2IrH6 stands out because it exhibits superconductivity at 160 K under ambient pressure. This study investigates methods to increase the superconducting transition temperature of this structure via atomic substitution and low-pressure treatment and assess the mechanical, thermodynamic, and dynamic stability of structures obtained by substituting Mg and Ir atoms in Mg2IrH6 with elements from the same groups using first-principles calculations. The findings identify 11 stable ternary compounds, 10 of which exhibit superconducting transition temperatures, with three compounds, Mg2CoH6, Mg2RhH6, and Mg2IrH6, exceeding 100 K, classifying them as high-temperature superconductors. Their superconducting figure of merit S values are 2.71, 3.35, and 3.83, respectively, suggesting strong practical application potential. The analysis results indicate that mid-frequency hydrogen phonons significantly enhance superconducting properties via electron-phonon coupling. The band structure study highlights the importance of van Hove singularities near the Fermi level. In addition, electron localization function and Fermi surface topology analyses reveal that the Fermi surface shape and density of states are crucial for increasing superconducting transition temperatures.

cond-mat.supr-con↗

arXiv2024

Determination of crystal structure and physical properties of Ru2Al5 intermetallic from first-principles calculations

Novel ordered intermetallic compounds have stimulated much interest. Ru-Al alloys are a prominent class of high-temperature structural materials, but the experimentally reported crystal structure of the intermetallic Ru2Al5 phase remains elusive and debatable. To resolve this controversy, we extensively explored the crystal structures of Ru2Al5 using first-principles calculations combined with crystal structure prediction technique. Among the calculated X-ray diffraction patterns and lattice parameters of five candidate Ru2Al5 structures, those of the orthorhombic Pmmn structure best aligned with recent experimental results. The structural stabilities of the five Ru2Al5 structures were confirmed through formation energy, elastic constants, and phonon spectrum calculations. We also comprehensively analyzed the mechanical and electronic properties of the five candidates. This work can guide the exploration of novel ordered intermetallic compounds in Ru-Al alloys.

cond-mat.mtrl-sci↗

arXiv2020

Accelerating inverse crystal structure prediction by machine learning: a case study of carbon allotropes

Based on structure prediction method, the machine learning method is used instead of the density function theory (DFT) method to predict the material properties, thereby accelerating the material search process. In this paper, we established a data set of carbon materials by high-throughput calculation with available carbon structures obtained from the Samara Carbon Allotrope Database. We then trained an ML model that specifically predicts the elastic modulus (bulk modulus, shear modulus, and the Young's modulus) and confirmed that the accuracy is better than that of AFLOW-ML in predicting the elastic modulus of a carbon allotrope. We further combined our ML model with the CALYPSO code to search for new carbon structures with a high Young's modulus. A new carbon allotrope not included in the Samara Carbon Allotrope Database, named Cmcm-C24, which exhibits a hardness greater than 80 GPa, was firstly revealed. The Cmcm-C24 phase was identified as a semiconductor with a direct bandgap. The structural stability, elastic modulus, and electronic properties of the new carbon allotrope were systematically studied, and the obtained results demonstrate the feasibility of ML methods accelerating the material search process.

cond-mat.mtrl-sci↗

arXiv2017

Pressure and strain effects on the optical properties of K4 phosphorus

An investigation of the mechanical, electronic, and optical properties of the recently reported material K4 phosphorus was made in this work. The K4 phosphorus has been proved to be mechanically and dynamically stable up to 7 GPa under hydrostatic pressure. We compared the elastic anisotropy, average acoustic velocity and Debye temperature of K4 phosphorus at 0 and 7 GPa. The ideal tensile at large strains of K4 phosphorus was also examined, with the results showing that it would cleave under the tensile strength of 8.5 GPa with the strain of 0.3. In addition, the effect of tensile strain and pressure on optical properties and band gap were studied.

cond-mat.mtrl-sci↗