Enhanced photodielectric effect in (0.88-x)Bi0.5Na0.5TiO3-0.12BaTiO3 -xBa(Ti0.5Ni0.5)O3-δ (BNBTNO) ceramics

In this work, solid solutions of (0.88-x)Bi0.5Na0.5TiO3-0.12BaTiO3- xBa(Ti0.5Ni0.5)O3-δ were designed and prepared. These compositions exhibit ferroelectricity at room temperature, with the tetragonal symmetry. The c/a values are varied from ∼1.0067 (x = 0.1) to ∼1.0208 (x = 0.04). A transition from the high-temperature relaxor state to the low-temperature ferroelectric state is demonstrated by the temperature dependence of dielectric data and Raman spectrum. The direct bandgap decreases from 3.40 eV for x = 0 to 3.16 eV for x = 0.1. The Ba(Ti0.5Ni0.5)O3-δ addition leads an additional optical absorption peak in the visible range. The obvious photodielectric effect was discovered. In particular, the relative permittivity of the x = 0.1 composition rises from ∼756 to ∼807 under light illumination.