Excitation Induced Mechanical Softening and Plastic Deformation in SiO2 and Al2O3

Abstract

Precise shaping of glass oxides is vital for microelectronics, but it traditionally requires high-temperature processes that can damage components. Recent experiments revealed low-temperature but electron-beam-induced superplastic deformation in amorphous silica, hinting at a nonthermal mechanism, though the role of electronic excitation remains unclear. In this work, we investigated the nonthermal effects of electronic excitation on the mechanical and electronic properties of α-SiO₂, α-Al₂O₃, κ-Al₂O₃, and amorphous SiO₂. While the glass oxides exhibit strong covalent or ionic bonding in the electronic ground state, characterized by high elastic constants and phonon frequencies, both properties significantly decrease under electronic excitation. Based on the results, we found that the superplastic deformation under electron beam irradiation is primarily driven by a bond-switching mechanism. This study provides theoretical insights into the mechanisms underlying superplastic deformation and offers a foundation for developing precise nanoscale shaping techniques for oxide materials.