Yellowish light emitting Dy3+ doped single phase – BaNb2O6 phosphors for solid state lighting applications

Abstract

BaNb2O6:Dy3+ phosphors that emit cool light has been synthesized via traditional solid-state reaction technique. Developed samples show orthorhombic structure with space group C2221 according to X-Ray Diffraction (XRD) and Rietveld structural refinement. Observations made using a scanning electron microscope (SEM) show densely packed particles with irregular shapes in the micrometre range. Optical bandgap was also determined using Diffuse Reflectance Spectroscopy (DRS). When excited at 389 nm, the as-prepared phosphors show blue (481 nm) and yellow (577 nm) emissions, which correspond to the 4F9/2 → 6HJ (J = 15/2, 13/2) transitions of Dy3+ ions. A thorough investigation has been done on the energy transfer process between Dy3+ ions. The optimized phosphor's computed chromaticity coordinates for the Commission Internationale de L'Eclairage (CIE) are x = 0.392 and y = 0.414. The values of CIE chromaticity coordinates and correlated colour temperature (CCT) of 3995 K endorse near cool light emission from the phosphor. Thermal stability and temperature dependent photoluminescence spectroscopy were studied for optimized phosphor which revealed that the phosphor can be a potential material for lighting applications at higher temperature. The study also reveals that BaNb2O6:Dy3+ phosphor could be a promising candidate for near ultra-violet (NUV) excited, yellowish LED applications.