Luminescence behavior of YVO4:Dy3+ phosphors with enhanced photoluminescence on co-doping Bi3+ ions

• Pure tetragonal phase of YVO4 on co-doping Bi3+ ions.
• Effective sensitizer effect of Bi3+ on Dy3+.
• Efficient energy transfer from Bi3+ to Dy3+.
• Emission of pure yellow light on co-doping Bi3+ ions.
• Multi-color phosphors on changing the excitation wavelength.

YVO4:Dy3+, Bi3+ phosphors were prepared successfully by co-precipitation method using ethylene glycol as a capping agent as well as reaction medium at a relatively low temperature of 150 °C. XRD patterns of all samples are well crystallized to a pure tetragonal phase of YVO4. The unit cell volume increases linearly with the Bi3+ ion concentrations suggesting the quantitative incorporation of Bi3+ ions in lattice sites of Y3+ in YVO4 matrix. On introduction of Bi3+ ions, the VO43− excitation band shifts to longer wavelengths. Energy transfer from V5+–Bi3+ CT state to Dy3+ was observed, giving rise to the characteristic visible emissions from Dy3+. The luminous intensity of the electric dipole transition as well as magnetic dipole transitions of Dy3+are enhanced significantly on co-doping of Bi3+ ions. The optimum concentration of Dy3+ for highest luminescence is found to be 1 at.% Bi3+ and the luminescence intensity increases on annealing samples at 500 °C. Furthermore, the emission colors of YVO4:5Dy3+ can be tuned from greenish blue to near white by changing the excitation wavelength and then to yellowish white on co-doping Bi3+ ions, making the phosphors a great potential for applications in fluorescent lamps and field emission displays (FEDs).

Emission spectra of Bi3+ co-doped YVO4:5Dy3+ as-prepared samples (Inset: CIE chromaticity of YVO4:5Dy3+, Bi3+ phosphors) under excitation of 280 nm.Figure optionsDownload as PowerPoint slide