Structural, thermodynamic, electronic, and optical properties of β-BeO phase ZnO under negative pressure: a first-principles study

This study presents the structural, thermodynamic, electronic, and optical properties of the β-BeO phase of ZnO under negative pressure calculated via first-principles method. We analyzed the phase transition by the local density approximation, and we find that the structural phase transition from wurtzite B4 to metastable β-BeO phase occurred at − 10.2 GPa. We used the Debye model to calculate the thermodynamic properties. The results show that the bulk modulus decreases with increasing temperature or decreasing pressure whereas the heat capacity and thermal expansion coefficient increase with increasing temperature or decreasing pressure. We employed the hybrid functional (Becke-Lee-Young-Parr exchange–correlation functional) method to predict the electronic and optical properties. The band structure calculations confirmed that the β-BeO phase possesses an indirect wider band gap than that of B4 phase. Redshift in band gap energy and optical properties are observed with decreasing pressure. The dielectric function ε1(ω) calculations validate that the β-BeO phase exhibits metallic behaviour at around 16.3 eV, whereas optical constants exploration has confirmed its transparent nature. The present study proves that the β-BeO phase ZnO may be potentially applicable in next-generation electronics. Additionally, it is helpful in material sciences to understand and examine the surrounding pressure during a variety of mineral formation processes.