Optical transitions and radiative properties of green emitting Ho 3+ :YVO 4 phosphor

The Ho -doped YVO phosphors were successfully prepared a sol-gel process in which citric acid was used as a chelating agent. X-ray diffraction (XRD) confirmed the effective inclusion of Ho ions into the host matrix with the formation of single phase YVO . The surface morphology was observed using SEM, the results of which showed a grain growth propensity and the agglomeration of prepared phosphors. The V-O (VO ) vibration mode was analyzed through Fourier transform infrared (FTIR) spectra. The spectroscopic properties were reported through UV-vis-NIR diffuse reflectance and photoluminescence (PL) spectra. The Judd-Ofelt (J-O) intensity parameters = 0.03 × 10 cm , = 0.22 × 10 cm , and = 0.23 × 10 cm obtained for the Y VO :0.03Ho phosphors were used to obtain the total transition probabilities ( ), radiative lifetimes ( ) and branching ratios ( ) for the certain transitions of Ho ions. Under 310 nm UV excitation, the visible emission spectra were measured, and an intense emission was observed around 541 nm (green region) for all the samples. The emission cross-section ( ) was 3.22 × 10 cm and the branching ratio ( ) was 0.816; these were investigated to capture the optimal concentration of the Y VO :0.03Ho phosphor. The estimated color coordinates were observed in the green region of CIE diagram. Ultimately, the superior properties ( ( ), , and color purity) of Y VO :0.03Ho phosphor may make it suitable for green emitting devices.