Structural and photoluminescence properties of red-light emitting YVO₄:Eu³⁺ phosphor synthesized by combustion and solid-state reaction techniques: a comparative study

In this work, Eu³⁺-doped YVO₄ phosphors were prepared via the solid-state reaction and the combustion method and the role of the synthesis process on the structural and emission properties of YVO₄:Eu³⁺ was investigated. Combustion synthesis yielded tetragonal phase with the space group I41/amd at a relatively low temperature and within short duration. The infrared spectra confirmed the characteristic bands of Y–O and V–O at around 450 and 830 cm⁻¹, while the samples prepared by combustion route exhibited C–O band and O–H–O bending vibrations at 1376 and 1637 cm⁻¹, respectively. The band gap energy of YVO₄, prepared by different methods, was found in the range of 3.6–3.73 eV. Upon UV excitation, the Eu³⁺-activated samples exhibited characteristic red–orange emission lines generated from 5D0 → 7F1,2 transitions of Eu³⁺ ions, respectively. The red-to-orange emission intensity ratio was found to be around 4.6 for all samples and proved to be competitive with the commercially available red phosphors. However, Y_1−xEu_xVO₄ phosphors, synthesized by solid-state reaction technique, exhibited elevated Eu³⁺ solubility and higher emission intensity than the samples prepared by combustion route owing to the larger crystallite size and minor C–O and O–H bonds. The critical concentration of Eu³⁺ ions for the maximum emission was estimated to be 2.0 and 0.5 mol% for the samples obtained by solid-state reaction and combustion method, respectively. The present phosphors were observed to be effectively excitable via the broad range of UV lights and were proved to be compatible with the UV LEDs. (author)