Crystal Phase Refinement and Optical Features of Highly Efficient Green Light Radiating Ca₉Y(VO₄)₇: Er³⁺ Nanophosphors for Emerging Solid-state Lighting Applications

Ca₉Y(VO₄)₇ phosphor activated with Er³⁺ ions have been developed by the urea-aided solution combustion technique. XRD profiles assisted with Rietveld refinement executed over-developed Er³⁺-activated Ca₉Y(VO₄)₇ powder, revealed a trigonal phase with the R3c space group. The electron microscope techniques namely TEM and SEM characterize the size and surface-linked qualities of the developed nanopowder, respectively. The uniform distribution of various elements in the nanocrystalline sample is authenticated by an energy-dispersive spectroscopy (EDS) system. The E_g (band gap) value of 3.64 eV for Ca₉Y_0.9Er_0.1(VO₄)₇ and 3.74 eV for Ca₉Y(VO₄)₇ has been estimated. Upon 382 nm excitation, Er³⁺: Ca₉Y(VO₄)₇ phosphor gives rise to the bright green emission owing to the ⁴S_3/2 → ⁴I_15/2 transition. The concentration quenching after 10 mol% composition of trivalent erbium ions is attributed to dipole-dipole interlinkages in accordance with Dexter's theory. The radiative lifetime (1.1083 ms), non-radiative rates (0.2079 ms^{- 1}), quantum efficiency (79%), along with colorimetric parameters i.e. CIE x (= 0.2577), y (= 0.4566), and CCT quantities offer Ca₉Y_0.9Er_0.1(VO₄)₇ as a proficient green radiating nanomaterial for RGB phosphors in solid-state applications.