Structural and optical behavior of nano-scaled luminous green-emitting Ca9Y(PO4)7:Tb3+ phosphor for competent lighting devices

Nano-sized Ca9Y(1-x)(PO4)7:xTb3+ phosphor series was synthesized via solution-combustion method for the first time. Rietveld study revealed the incorporation of Tb3+ ions into monoclinic host lattice of R3c(1 6 1) space symmetry. The diffuse reflectance spectral investigations depicted the lowering of band-gap (Eg) value from 4.44 to 4.27 eV for Ca9Y(PO4)7 and Ca9Y0.30Tb0.70(PO4)7, respectively. Under near-Ultraviolet excitation, PL spectra yielded luminous green emission at 544 nm (5D4 → 7F5). For Ca9Y0.30Tb0.70(PO4)7 system, quantum efficiency and CIE chromaticity coordinates were determined to be 96% and (0.252, 0.564), respectively. The results as-obtained predict the potential implications of Ca9Y0.30Tb0.70(PO4)7 nanophosphor as primary green component in WLEDs.