Optical properties of sonochemically synthesized rare earth ions doped BaTiO3 nanophosphors: Probable candidate for white light emission

Undoped BaTiO3 and doped BaTiO3:RE (where RE=Sm3+, Ce3+, Dy3+, Tb3+and Eu3+) nanophosphors were synthesized sonochemically and characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), EDX (energy dispersive X-ray spectroscopy) and photoluminescence (PL) spectrophotometry. The resultant nanophosphors are single phase and rod shaped. The doped samples showed multicolor emission on single wavelength excitation. The luminescence decay curves for all the BaTiO3:RE3+ (RE3+=Eu3+, Dy3+, Sm3+, Tb3+) samples fitted well into bi-exponential decay fit indicating availability of the dopant ions on surface and core regions of the sample. In case of the double doped BaTiO3:Sm3+(2.5%):Tb3+(2.5%) sample, the green emission from Tb3+ was almost negligible. However, addition of Ce3+ ions in the Sm3+ and Tb3+ double doped host yielded relatively stronger green emission which has been assigned to energy-transfer between the Ce3+ and Tb3+ ions. The CIE coordinates of this triple doped BaTiO3:Ce3+(2%): Tb3+(2%):Sm3+(1%) sample lie in the white light region of the chromaticity diagram and has a quantum efficiency of 58%. Thus, this sample shows promise as good phosphor material for new lighting devices.