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

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 degrees 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 degrees C. Furthermore, the emission colors of YVO4:5Dy(3+) can be tuned from greenish blue to near white by changing the excitation wavelength and then to yellowish white on codoping Bi3+ ions, making the phosphors a great potential for applications in fluorescent lamps and field emission displays (FEDs). (C) 2013 Elsevier B.V. All rights reserved.