Solid state diffusion and amalgamating anionic exchange at a KNaSO phosphors activated with Eu , Dy and Sm rare earth ions to enhance w-LED performance.

In present work, KNa(SO ) phosphors doped with different concentrations of rare earth Eu , Sm and Dy ions (0.05, 0.1, 0.3, 0.5, 0.7, 1 mol%) were synthesized using a solid-state diffusion technique. Photoluminescence (PL) investigations were carried out for the whole range of Eu , Sm and Dy -doped phosphors; rare earth ions that retained maximum PL intensity were selected for advanced anionic exchange. In the present investigation, phosphors KNa(SO ):Eu (1 mol%), KNa(SO ):Dy  (0.5 mol%) and KNa(SO ):Sm (0.3 mol%) had the highest PL intensity, and were therefore selected for further anionic substitution of sulphate anions with different concentrations of vanadate, phosphate, and tungstate anions, such as KNa(SO ) (MO ) : W (where W = Eu 1 mol%, Dy 0.5 mol% and Sm 0.3 mol%; MO  = PO , VO , WO ; and x = 0.1, 0.3, 0.5, 0.7, 1). Structural and molecular environments of the substituted phosphors were characterized individually using X-ray diffraction and Fourier transform infrared spectroscopy. In-depth morphological investigations of the prepared phosphors were undertaken using scanning electron microscopy. For the principal investigation on enhancement of white light-emitting diode (w-LED) performance, the PL properties of all the synthesized phosphors were studied analytically. Emission intensity ratios for KNa(SO ):Eu 1 mol%, KNa(SO ) (PO ) :Eu 1 mol%, KNa(SO ) (VO ) :Eu 1 mol%, and KNa(SO ) (WO ) :Eu 1 mol% were 1:1.15:1.23:0.08. PL intensity ratios for the phosphors KNaSO :Dy 0.5 mol% and KNa(SO ) (PO )0.1:Dy 0.5 mol% was 1:2. The ratio of PL intensity was 1:3.2:0.8 for KNa(SO ):Sm 1 mol%, KNa(SO ) (PO4) :Sm 0.3 mol%, and KNa(SO ) (VO ) :Sm 0.3 mol% phosphors, respectively. Chromaticity investigations were carried out using Commission Internationale de l'Éclairage colour co-ordinate diagrams, which suggested that the prepared Eu -doped and Sm -doped phosphors would be prospective candidates for red and green LEDs, respectively, whereas Dy -doped phosphors showed emission in the blue and yellow regions. The entire study indicated that amalgamation of anionic exchange at a KNaSO phosphor activated with Eu , Dy and Sm rare earth ions could generate and enhance white light emission.