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

The Ho(3+)-doped YVO(4) phosphors were successfully prepared via a sol–gel process in which citric acid was used as a chelating agent. X-ray diffraction (XRD) confirmed the effective inclusion of Ho(3+) ions into the host matrix with the formation of single phase YVO(4). 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(4)(3−)) 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 Ω(2) = 0.03 × 10(−20) cm(2), Ω(4) = 0.22 × 10(−20) cm(2), and Ω(6) = 0.23 × 10(−20) cm(2) obtained for the Y(0.97)VO(4):0.03Ho(3+) phosphors were used to obtain the total transition probabilities (A(T)), radiative lifetimes (τ(rad)) and branching ratios (β) for the certain transitions of Ho(3+) 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 σ(P)(λ) was 3.22 × 10(−21) cm(2) and the branching ratio (β) was 0.816; these were investigated to capture the optimal concentration of the Y(0.97)VO(4):0.03Ho(3+) phosphor. The estimated color coordinates were observed in the green region of CIE diagram. Ultimately, the superior properties (σ(P)(λ), β, and color purity) of Y(0.97)VO(4):0.03Ho(3+) phosphor may make it suitable for green emitting devices.