Pb-free semiconductor ferroelectrics: A theoretical study of Pd-substituted Ba(Ti1-xCex)O3 solid solutions

We use first-principles density-functional-theory calculations to investigate the ground state structures of Ba(Ti1-xCex)O-3 solid solutions containing Pd. Previous studies have shown that the properties of BaTiO3, a Pb-free ferroelectric ABO(3) perovskite, can be tailored via B-site substitution. In the present study, we substitute Ce for Ti to increase the overall volume of the perovskite, to then accommodate an O-vacancy-stabilized Pd substitution. Using the LDA + U method, we predict that these proposed materials will display a decreased band gap compared to BaTiO3 while maintaining polarization. These features, combined with their environmentally friendly characteristics make these materials promising candidates for use as semiconducting ferroelectrics in solar-energy conversion devices.