Investigation on the Stability, Elastic Properties, and Electronic Structure of Mg2Si Doped with Different Concentrations of Cu: A First-Principles Calculation

Herein, the effects of Cu doping with different concentrations on the stability, elastic properties, and electronic structure of Mg2Si are investigated by first-principles calculations based on density functional theory. The research results show that Mg2Si and Mg8-xSi4-yCux+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 Mg2Si lattices, and the alloying ability is stronger than that of Mg8Si4-yCuy (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 Mg2Si alloy system. The bonding modes of the crystal are also changed. The Si-Cu covalent bond formed by Mg8-xSi4Cux (x = 0.125, 0.25, 0.5, 1) further increases the structure stability. Meanwhile, Mg7Si4Cu and Mg8Si3Cu 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 Mg2Si. These investigations will provide some theoretical basis for the application of Mg2Si intermetallic compounds in structural materials and thermoelectric materials.

Automated summary

The effects of Cu doping with different concentrations on the stability, elastic properties, and electronic structure of Mg2Si were investigated. Cu atoms tend to occupy Mg sites in Mg2Si lattices and form Si-Cu covalent bonds to enhance structure stability. Cu doping improves the elastic and plastic properties of the Mg2Si alloy system and changes Mg7Si4Cu and Mg8Si3Cu from semiconducting to metallic state.