Density Functional Theory Investigation of Bi(Ga,Al)O₃Solid Solution for High-Performance Lead-Free Piezoelectric Materials

Abstract

In this work, we have investigated the ferroelectric property of BiAl_xGa_(1−x)O₃with x = 0.00, 0.25, 0.50, 0.75, and 1.00 for replacement of the widely use, PZT which is toxic. The techniques used are density functional theory with local density approximation (LDA) as well as projector augmented-wave method (PAW). The composition (x) was varied via setting the appropriated supercell. The solid solutions in both tetragonal (P4 mm) and rhombohedral (R3c) phase have been simulated to determine crystal stability, phase transition, and ferroelectric properties. From the results, the expected morphotropic phase boundaries (MPB) have not been observed because all R3c structures are more energetically stable than those of P4 mm. Therefore, Bi(Ga,Al)O₃solid solution cannot display higher ferroelectricity than that of pure BiGaO₃. However, the calculated polarization of Bi(Ga,Al)O₃are still very high compared to other ferroelectric materials, e.g. AgNbO₃and BaTiO₃. This suggests that the considered solid solution could be one of lead-free candidates for future industrial applications.

Keywords:

• Density functional theory
• lead-free piezoelectrics
• local density approximation
• Bi(Ga,Al)O₃solid solution
• augmented-wave method

Acknowledgments

The Graduates School of Chiang Mai University, Development and Promotion of Science and Technology Talents Project (DPST), Department of Physics and materials science, Faculty of Science, Chiang Mai University are acknowledged for the support.