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

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 ⁴F_9/2 → ⁶H_J (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.