Investigation on the Stability, Elastic Properties, and Electronic Structure of Mg 2 Si Doped with Different Concentrations of Cu: A First‐Principles Calculation

• Published in: physica status solidi (b) Vol. 258; no. 5
• Main Authors: Ma, Tianyu, Liu, Tongyu, Ren, Yuyan, Li, Yingmin
• Format: Journal Article
• Language: English
• Published: 01.05.2021
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.202000597

Herein, the effects of Cu doping with different concentrations on the stability, elastic properties, and electronic structure of Mg 2 Si are investigated by first‐principles calculations based on density functional theory. The research results show that Mg 2 Si and Mg 8− x Si 4− y Cu x + y ( x , y ) = {(0.125, 0), (0, 0.125), (0.25, 0), (0, 0.25), (0.5, 0), (0, 0.5), (1, 0), (0, 1)} are stable in the system. The Cu atoms tend to preoccupy Mg sites in Mg 2 Si lattices, and the alloying ability is stronger than that of Mg 8 Si 4− y Cu y ( y  = 0.125, 0.25, 0.5, 1). Although all dopants are brittle phases, the doping behavior of Cu atoms improves the elastic and plastic properties of the Mg 2 Si alloy system. The bonding modes of the crystal are also changed. The SiCu covalent bond formed by Mg 8− x Si 4 Cu x ( x  = 0.125, 0.25, 0.5, 1) further increases the structure stability. Meanwhile, Mg 7 Si 4 Cu and Mg 8 Si 3 Cu are changed from semiconducting to metallic state by energy band structure analysis. It not only increases the carrier concentration, but also reduces the free electron transition energy, which improves the conductivity of the intrinsic Mg 2 Si. These investigations will provide some theoretical basis for the application of Mg 2 Si intermetallic compounds in structural materials and thermoelectric materials.