S.J. Dhoble

Combustion synthesis of Ce3+, Eu3+ and Dy3+ activated NaCaPO4 phosphors

Abstract The preparation of NaCaPO4 doped with rare earth (RE) ions Ce3+, Eu3+ and Dy3+ by combustion method was described. Under UV excitation (251 nm) of NaCaPO4:Ce3+ showsd emission (367 nm) in UV range. When NaCaPO4:Dy3+ phosphor was excited at 349 nm, the emission spectrum showed intense bands at 482 nm (blue) and 576 nm (yellow). In Eu activated NaCaPO4 phosphor, the emission spectrum showed a dominant peak at 594 nm (orange) while others were at 614 and 621 nm (red) when excited at 393 nm. The prepared phosphor was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL) measurement. Thus, the photoluminescence behavior of NaCaPO4:Ce3+ was strongly suggested for scintillator. Likewise, Eu3+ and Dy3+ activated NaCaPO4 phosphors were recommended for near-UV white light-emitting diodes (LEDs).

Combustion synthesis of Na2Sr(PO4)F:Dy3+ white light emitting phosphor

The synthesis, X-ray diffraction, photoluminescence, TGA/DTA and FTIR techniques in Dy(3+) activated Na(2)Sr(PO(4))F phosphor are reported in this paper. The prepared phosphor gave blue, yellow and red emission in the visible region of the spectrum at 348 nm excitation. CIE color co-ordinates of Na(2)Sr(PO(4))F:Dy(3+) are suitable as white light-emitting phosphors.

Photoluminescence and thermoluminescence characteristics of KXSO4Cl : Eu (X = Zn or Mg) halosulfate phosphor

Polycrystalline KZnSO4Cl : Eu and KMgSO4Cl : Eu prepared by a wet chemical method have been studied for their thermoluminescence (TL) and photoluminescence (PL) characteristics. The PL emission spectra of the phosphor suggests the presence of Eu2+ and Eu3+ in the host compound occupying two different lattice sites. The TL glow curve of the KZnSO4Cl : Eu compounds has a simple structure with prominent peaks at 200 and 290 °C, while KMgSO4Cl : Eu peaks at 165 and 265 °C. The TL sensitivity of the phosphors is compared with CaSO4 : Dy and is found to be 3.4 and 2.4 times less in KZnSO4Cl : Eu and KMgSO4Cl : Eu phosphors, respectively.

Photoluminescence enhancement of red-emitting GdVO4:Eu and YVO4:Eu phosphors by adding zinc

Abstract We synthesized the rare-earth activated R 0.94- x Eu 0.06 Zn x VO 4 (R: Gd and Y; 0≤ x ≤0.08) phosphors with a spherical morphology and a smooth surface by the ultrasonic spray pyrolysis. The annealed R 0.94- x Eu 0.06 Zn x VO 4 crystallized in the tetragonal zircon type structure, belonging to the space group of I 4 1 / amd . The incorporation of a small amount of Zn to R 0.94 Eu 0.06 VO 4 improved the emission characteristics. The emission intensities of the Gd 0.88 Eu 0.06 Zn 0.06 VO 4 and Y 0.9 Eu 0.06 Zn 0.04 VO 4 phosphors at 619 nm were 72% and 21% stronger than those of the Gd 0.94 Eu 0.06 VO 4 and Y 0.94 Eu 0.06 VO 4 phosphors, respectively. We demonstrated that the addition of Zn to R 0.94 Eu 0.06 VO 4 was quite effective for improving the photoluminescent properties.

Lyoluminescence, thermoluminescence and photodecomposition in microcrystalline powder of KCl, KBr, KI and KI:KNO3 crystals

Abstract Particle size effect in γ-radiolysis of KCl, KBr, KI and KI:KNO 3 single crystal and microcrystalline powders has been studied using optical absorption, thermoluminescence and lyoluminescence (LL) techniques. Colouration characteristics in KCl, KBr microcrystalline powders are reported to be different from KI and KI:KNO 3 for various particle sizes. F centre concentration decreases with decreasing particle size in KCl and KBr. While in KI and KI:KNO 3 , V centre concentration increases, on the other hand F centre concentration decreases with decreasing particle size. Rate of formation of I 3 − is 100 times less in KI:KNO 3 as compared to KI crystal and powders. This is attributed to the higher rate of F-H recombination due to the impurity ions in KI:KNO 3 . Colour centre concentration, particle size and dissolution rate, all three factors affect LL intensity together. The results presented here may be considered as of only academic interest in solid state materials.

Photoluminescence in rare earth-doped complex hexafluoride phosphors

In this study, using a simple combustion process and a wet chemical process, fluorides showing intense photoluminescence were prepared and developed as low-cost phosphors. The prepared phosphors were characterized by photoluminescence (PL) techniques. PL emission spectra of the phosphor suggest the presence of Eu(3+) as well as Eu(2+) ions in LiMgBF(6):Eu and Li(2) NaBF(6):Eu lattice sites. This article summarizes the fundamentals and possible applications of optically useful inorganic fluoride with visible photoluminescence of doped Eu(3+) and Eu(2+) ions. Our results on LiMgBF(6):Ce and Li(2) NaBF(6):Ce are also reported.

Eu3+ (orange/red) luminescence in LiXSO4Cl (X = Mg, Zn) halosulfate phosphor.

The wet chemical synthesis, X-ray diffraction and photoluminescence characteristics in alkaline halosulfate phosphors such as LiMgSO4Cl:Eu and LiZnSO4Cl:Eu are reported in this paper. The effect of Li ion on Eu3+ luminescence (5D(0) --> 7F(2) electronic transition) and incorporation of Eu3+ ion in lithium base alkaline halosulfate phosphor has been studied.

Solid-State Lighting

Solid-state lighting (SSL) is energy-saving, energy-efficient green technology that has the potential to replace conventional lighting systems through the use of light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), and polymer light-emitting diodes (PLEDs). The future potential of this cutting-edge research can be used to creating lighting that is not only environmentally friendly but that is also cost efficient. In this chapter, new advances in SSL such as OLEDs, LEDs, and PLEDs are discussed along with the challenges that must be overcome to fully implement them in the lighting industry.