Microstructure and composition driven ferroelectric properties of Er3+ doped lead-free multifunctional 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 ceramics

The x mol Er3+ doped 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 (BNT-BT:xEr3+) ceramics were prepared and their microstructure, electric and luminescent properties were systematically investigated. The microstructure, electric and photoluminescent properties of BNT-BT:xEr3+ ceramics are strongly dependent on the Er3+ composition. The crystal parameters and grain sizes of BNT-BT ceramics strongly depend on Er3+ composition due to the different replacement positions of Er3+ with the increase of Er3+ composition. The ferroelectric and dielectric properties are firstly enhanced due to the decrease of crystal defects, and then suppressed because of the decrease of grain size and the phase transition from R3c to P4bm phase with the increase of Er3+ composition. The discharge energy storage density is improved with a relative change of 67.58% for BNT-BT:1.0%Er3+ ceramics. Furthermore, the depolarization temperature Td and the relaxor antiferroelectric temperature TRE are decreased with the increase of Er3+ composition. But the Curie temperature Tm is enhanced for x< 0.6% as the A-site doping limits the transition from ferroelectric to paraelectric phase. The BNT-BT:xEr3+ ceramics exhibit a strong green emission at 548 nm under the excitation of 487 nm light. The investigation provides a new opportunity in exploring electro-optical coupling materials.