TUNABLE EMISSION COLOR OF NOVEL Y3NbO7:xDy3+ PHOSPHOR

Powders of Y3NbO7:xDy(3+) (x = 0.5, 1, 1.5, 3 and 5 mol%) were produced through a solid-state process. X-ray diffraction investigations confirm the fluorite-type structure (space group F-m (3) over barm) of powders with crystallite size in the range of 19-60 nm. Both the photoluminescence excitation and emission spectra revealed the presence of defects within the material. With different excitation wavelengths, the emission spectra exhibited distinct emission patterns. At each excitation wavelength, the emission was quenched at Dy3+ concentration higher than 1 mol%. The decay time measurements of the highest intensity emission revealed a progressive decrease from 0.472 milliseconds for x = 0.5 mol% to 0.246 milliseconds for x = 5 mol%. The CIE chromaticity coordinates investigation revealed that the emission color may be altered by varying the excitation wavelength, ranging from blue (excitation at 333 nm) and near-white (excitation at 353 nm and 390 nm) to orange (excitation at 457 nm). The chromaticity of emission under 353 nm and 390 nm excitation validated the material's suitability as an almost-white phosphor.