Enhanced piezoelectricity and photoluminescence in Dy-modified 0.94(Bi1-xDyx)0.5Na0.5TiO3-0.06BaTiO3 lead-free multifunctional ceramics

Lead-free 0.94(Bi1-xDyx)(0.5)Na0.5TiO3-0.06BaTiO(3) ceramics were prepared by an ordinary sintering method and their piezoelectric and photoluminescent properties were studied. All the ceramics possess a pure perovskite structure with the coexistence of the rhombohedral and tetragonal phase. The partial substitution of Dy3+ for Bi3+ enhanced effectively the piezoelectricity of the materials. The optimum piezoelectricity is obtained at x = 0.025, giving d(33) = 190 pC/N and k(P) = 37.2 %, respectively. After the addition of Dy3+, excellent photoluminescence of the ceramics is induced. The Dy-doped ceramics exhibit strong emissions at similar to 478 nm (blue) and similar to 575 nm (yellow), corresponding to F-4(9/2) -> H-6(15/2) and F-4(9/2) -> H-6(13/2) of Dy3+ transitions, respectively. The optimum photoluminescence of the ceramics is reached at x = 0.025. The ceramics with the doping of 2.5 mol% Dy3+ exhibit simultaneously good piezoelectricity, strong ferroelectricity and excellent photoluminescence, suggesting a promising application in the electro-optic devices.