Tunable white light emitting Sr2V2O7:Bi3+ phosphors: Role of bismuth ion

Phase purity, optical properties and defects in new near white light emitting rare earth free Sr2V2O7:Bi-3(+) phosphors were investigated. Emission spectrum of Sr2V2O7 displayed two peaks at all excitation wavelength approximately around 450 (P-1) and 600 nm (P-2). With increase in the excitation wavelength; emission intensity increases and there is a red and blue shift in Peak P-1 and P-2, respectively. On bismuth doping, the two Peaks P-1 and P-2 slowly starts merging and become a single broad peak at 5% doping. Bismuth doping also reduces the emission peak energy. This is attributed to substitution of Bi3+ at Sr2+ site which would distort VO4 tetrahedra, thereby reducing the energy difference between the T-3 and (1)A levels of VO43- distorted tetrahedral. This dual role of bismuth doping and excitation energy leads to interesting tunability in white emission from cool to warm white. This opens a new arena in phosphor research because of great role of white LEDs (both warm and cool) in outdoor and indoor lighting. [GRAPHICS] .