Optimization of energy storage characteristics of xBiInO₃-(1-x)BiFeO₃ solid-solution thin films by controlling BiInO₃ concentration

We optimized the energy storage properties of xBiInO₃-(1-x)BiFeO₃ (BIO) solid solution thin films on Pt/TiO₂/SiO₂/Si substrates by controlling the BiInO₃ concentration. The BIO thin films with BiInO₃ concentrations ranging from 10 to 50 mol% deposited by pulsed laser deposition were preferentially grown as c-oriented polycrystalline thin films. As the BOI concentration increases, the BIO thin films change from the rhombohedral (R) phase to a mixed phase of the R-phase and orthorhombic (O)-phase with reduced ferroelectric polarization, and then to the O-phase. At the same time, the grains become smaller and the distribution of a-domains increases, resulting in the relaxor ferroelectric properties. Therefore, the change of the BIO thin films from ferroelectric properties to the relaxor ferroelectric properties is due to a combination of phase changes, grain size changes, and a-domain formation. These relaxor ferroelectric properties enable the BIO thin films to have improved energy storage efficiency by improving recoverable energy density and reducing loss energy density. In particular, the BIO thin film with a BiInO₃ concentration of 40 mol% showed a high recoverable energy density of about 50.7 J/cm³ and a high energy storage efficiency of about 78.5 %.