ABSTRACT
In present work, KNa(SO4 ) phosphors doped with different concentrations of rare earth Eu3+ , Sm3+ and Dy3+ 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 Eu3+ , Sm3+ and Dy3+ -doped phosphors; rare earth ions that retained maximum PL intensity were selected for advanced anionic exchange. In the present investigation, phosphors KNa(SO4 ):Eu3+ (1 mol%), KNa(SO4 ):Dy3 + (0.5 mol%) and KNa(SO4 ):Sm3+ (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(SO4 )1-x (MO4 )x : W (where W = Eu3+ 1 mol%, Dy3+ 0.5 mol% and Sm3+ 0.3 mol%; MO4 = PO4 , VO4 , WO4 ; 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(SO4 ):Eu3+ 1 mol%, KNa(SO4 )0 (PO4 )1 :Eu 1 mol%, KNa(SO4 )0.9 (VO4 )1 :Eu 1 mol%, and KNa(SO4 )0.9 (WO4 )0.1 :Eu 1 mol% were 1:1.15:1.23:0.08. PL intensity ratios for the phosphors KNaSO4 :Dy 0.5 mol% and KNa(SO4 )0.9 (PO4 )0.1:Dy 0.5 mol% was 1:2. The ratio of PL intensity was 1:3.2:0.8 for KNa(SO4 ):Sm 1 mol%, KNa(SO4 )0.5 (PO4)0.5 :Sm 0.3 mol%, and KNa(SO4 )0.7 (VO4 )0.3 :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 Eu3+ -doped and Sm3+ -doped phosphors would be prospective candidates for red and green LEDs, respectively, whereas Dy3+ -doped phosphors showed emission in the blue and yellow regions. The entire study indicated that amalgamation of anionic exchange at a KNaSO4 phosphor activated with Eu3+ , Dy3+ and Sm3+ rare earth ions could generate and enhance white light emission.
Subject(s)
Europium , Luminescence , Dysprosium , Prospective Studies , SulfatesABSTRACT
In this work, RE3+ (Eu, Ce and Sm)-activated Ca10 (PO4 )6 F2 (fluorapatite) phosphors were synthesized by doping with different apatite minerals (SO4 , VO4, WO4 ) using a solid-state diffusion method. Optical and structural characterizations were performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy, and photoluminescence (PL) spectroscopy. XRD characterization showed the crystalline nature of the phosphor. PL properties were investigated under ultraviolet light excitation for all three rare earths. CIE chromaticity revealed the colour emitted in the visible region. Luminescence intensity was enhanced considerably by tuning the host matrices after core-shell formation by substitution with other ions producing promising candidates for white light-emitting diode materials.
Subject(s)
Doping in Sports , Luminescent Agents , Europium , Luminescence , MineralsABSTRACT
Thermoluminescence (TL) materials exhibit a wide range of applications in different areas such as personal dosimetry, environmental dosimetry, medical research etc. Doping of different rare earth impurities in different hosts is responsible for changing the properties of materials useful for various applications in different fields. These materials can be irradiated by different types of beams such as γ-rays, X-rays, electrons, neutrons etc. Various radiation regimes, as well as their dose-response range, play an important role in thermoluminescence dosimetry. Several TL materials, such as glass, microcrystalline, nanostructured inorganic materials and recently developed materials, are reviewed and described in this article.
