Ferroelectric properties and large electric field-induced strain of Eu3+-doped Na0.5Bi0.5TiO3–BaTiO3 lead-free ceramics

Eu3+-doped lead-free piezoelectric ceramics, 0.937Na0.5Bi0.5−xEuxTiO3-0.063BaTiO3 (abbreviated as NBExT-BT, where x = 0, 0.003, 0.005, 0.01, 0.013, 0.015, 0.017, and 0.02), were synthesized using a conventional solid-state synthesis method. All the component samples were crystallized in a pure perovskite structure without a secondary phase. The introduction of Eu3+ caused the evident variation of the dielectric, ferroelectric and luminescence properties. The remanent polarization and coercive field of the pure NBT-BT are Pr ∼29.24 μC/cm2, Ec∼39.33 kV/cm, respectively. The maximum of the remanent polarization Pr of ∼38.02 μC/cm2 at room temperature and the highest dielectric constant of 6899 with a frequency of 1 kHz were obtained for NBE0.003T-BT. The maximum bipolar strain Smax of ∼0.91% and the minimum of coercive field Ec ∼18.45 kV/cm were achieved by the NBE0.015T-BT, resulting from the formation of a double hysteresis loop. For all the components, Eu3+ doping stabilized the antiferroelectric phenomenon at high temperature. Furthermore, the polarized NBE0.015T-BT had the strongest fluorescence luminescence intensity as well as a fluorescence lifetime reaching 785.98 μs.