Band gap narrowing and electrical properties of (1-x)BaTiO3-xSrFe0.5Nb0.5O3 lead-free ceramics

The composite materials in the form of (1- x )BaTiO 3 - x SrFe 0.5 Nb 0.5 O 3 ((1- x )BT- x SFN) are synthesized via the solid-state reaction route. Structure, optical behaviors, and electrical properties of (1- x )BT- x SFN are studied. It can be noted that the structure of the synthesized solid solution changes from the tetragonal phase to the cubic phase with increase of x -value. Due to the increase in content of double perovskite SFN, the optical band gaps of doped BT decrease to a minimum of 2.66 eV, which is smaller than that of pure BT (3.21 eV). However, the ferroelectric property deteriorates with the addition of dopants, which result from the lattice distortion caused by the substitution of Sr 2+ and Fe 3+ /Nb 5+ for Ba 2+ and Ti 4+ , respectively. These results provide new insights into the control of the structure, optical behaviors and ferroelectric properties in BT-based oxides.