Realizing giant photodielectric effect in Bi₅Ti₃Fe_1-xCr_xO₁₅ solid-solution ceramics by dual-phase structure

Light control of dielectric properties of ferroelectrics is crucial for the development of photoelectric devices. A giant photodielectric effect Δε_r ~ 7.4% was achieved in continuous-component solid-solution ceramics Bi₅Ti₃Fe_1-xCr_xO₁₅ (0 ≤ x ≤ 1) with a dual-phase structure. The decreasing phase fraction of the high-symmetry Fmm2 phase/low-symmetry A2₁am phase induces a linearly narrowing bandgap and improves visible-light absorption. The light-triggered “on-off” switchable photocurrent and the released electron-hole pairs at the phase boundary contribute to the excellent photodielectric effect. Finite element simulations confirmed that microsphere grains play a critical role in generation of photocarriers and photocurrent. These results demonstrate that the dual-phase structure can boost the photoelectric response, endowing potential applications of photodielectric devices.