Energy transfer process in a rare earth (Ce3+ , Dy3+ , Sm3+ )-doped nanocrystalline phosphate phosphor.

This work presents the optimized luminescence spectra for the Ce3+ ,Sm3+ -doped NaSrPO4 phosphor that was synthesized using a wet chemical method. Ce3+ and Sm3+ are activator impurities that show spectral splitting bands that corresponds to the d-f and f-f transitions, respectively. These impurity elements shows the characteristics spectral bands when doped with the NaSrPO4 host lattice. Spectral splitting in the Ce3+ excitation band was monitored in the 240-340 nm range, in which the observed bands were located at 269 nm, 292 nm and 321 nm, and emission bands were observed in the broad spectral range 330-430 nm. However, when Sm3+ ion was doped in the same host lattice we obtained a characteristic emission band at 590 and 645 nm in the orange-red region, under sharp excitation bands located at 345, 361, 375, and 403 nm respectively. Also, we carried out energy transfer analysis in the Ce3+ /Dy3+ -doped NaSrPO4 phosphor. Further crystalline phase and the nanophase nature of the phosphor compound were confirmed using X-ray diffraction and transmission electron microscopy analyses.

Intense green-, red-emitting Tb3+ , Tb3+ /Bi3+ -doped and Sm3+ , Sm3+ /La3+ -doped Ca2 Al2 SiO7 phosphors.

This paper focuses on an optical study of a Tb3+ /Bi3+ -doped and Sm3+ /La3+ - doped Ca2 Al2 SiO7 phosphor synthesized using combustion methods. Here, Ca2 Al2 SiO7 :Sm3+ showed a red emission band under visible light excitation but, when it co-doped with La3+ ions, the emission intensity was further enhanced. Ca2 Al2 SiO7 :Tb3+ shows the characteristic green emission band under near-ultraviolet light excitation wavelengths, co-doping with Bi3+ ions produced enhanced photoluminescence intensity with better colour tunable properties. The phosphor exhibited better phase purity and crystallinity, confirmed by X-ray diffraction. Binding energies of Ca(2p), Al(2p), Si(2p), O(1s) were studied using X-ray photoelectron spectroscopy. The reported phosphor may be a promising visible light excited red phosphor for light-emitting diodes and energy conversion devices.

Ultrasound assisted synthesis of CaF2 :Eu3+ phosphor nanoparticles.

In this work, the optical and structural properties of ultrasonically prepared CaF2 :Eu3+ nanoparticles have been reported. Ultrasonically prepared CaF2 :Eu3+ phosphor shows orange, red emission bands at 591 nm and 612 nm, respectively, when it is excited by 394 light-emitting diode (LED) excitation wavelengths. Further phosphor materials are well characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) techniques to confirm the phase purity, metal oxygen (MO) bonding and crystallites size of the materials. Here synthesized materials show a tube-like structure under 100 nm resolution and 0.1 mol% is the best doping value of the europium ion (Eu3+ ) in calcium fluoride (CaF2 ) that shows highest intensity when prepared with an ultrasound assisted method.

Novel optical properties of Ca12 Al10.6 Si3.4 O32 Cl5.4 :Ce3+ ,Li+ phosphor for solid-state lighting.

This article reports a novel blue emission in a series of Ca12 Al10.6 Si3.4 O32 Cl5.4 :Ce3+ phosphor under excitation in the near-UV wavelength range. This phosphor was prepared using the combustion method. Here, the Ce3+ emission band is observed over a broad range of 380-550 nm, under 365 nm excitation, and is due to 5d-4f transition. The effect of a Li+ charge compensator on the emission properties of the phosphor was also investigated for the first time. X-Ray diffraction confirmed the phase purity of the synthesized phosphor. The surface morphology and elemental composition of the phosphor were studied using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Copyright © 2016 John Wiley & Sons, Ltd.

Impact of temperature on Na2 Sr(PO4)F:Eu3+ phosphor.

In this article, we report the synthesis of Na2 Sr1-x (PO4)F:Eux phosphor via a combustion method. The influence of different annealing temperatures on the photoluminescence properties was investigated. The phosphor was excited at both 254 and 393 nm. Na2 Sr1-x (PO4)F:Eux (3+) phosphors emit strong orange and red color at 593 and 612 nm, respectively, under both excitation wavelengths. Na2 Sr1-x (PO4)F:Eux (3+) phosphors annealed at 1050°C showed stronger emission intensity compared with 600, 900 and 1200°C. Moreover, Na2 Sr1-x (PO4)F:Eux (3+) phosphor was found to be more intense when compared with commercial Y2 O3:Eu(3+) phosphor.

Photoluminescence in K3 Ca2 (SO4 )3 Cl-doped Eu(3+) phosphor.

In this article we report Eu(3+) luminescence in novel K3 Ca2 (SO4 )3 Cl phosphors prepared by wet chemical methods. The Eu(3+) emission was observed at 594 nm and 615 nm, keeping the excitation wavelength constant at 396 nm nearer to light-emitting diode excitation, Furthermore, phosphors were characterized by X-ray diffraction for the confirmation of crystallinity. The variation of the photoluminescence intensity with impurity concentration has also been discussed. Thus, prominent emission in the red region makes prepared phosphors more applicable for white light-emitting diodes.

Solution combustion synthesis of Dy(3+) and Ce(3+) activated Na2ZnSi2O6 phosphors.

Here we first time reported Dy(3+) and Ce(3+) luminescence in novel Na2ZnSi2O6 phosphors by solution combustion synthesis prepared at 550 °C. Emission spectra of Na2ZnSi2O6:Dy(3+) phosphor was observed at 470 nm and 576 nm keeping excitation wavelength at 350 nm, where as Na2ZnSi2O6:Ce(3+) shows emission band at 452 nm monitoring excitation at 354 nm. XRD analysis was carried out to observe crystalline nature of the prepared phosphor.

Investigation on luminescence properties of Eu2+-doped Ba3Al2O5Cl2 phosphor for near-UV-excited white LEDs.

Ba3Al2O5Cl2:Eu(2+) phosphor was prepared by combustion synthesis (CS). The prepared phosphor was excited at 329 nm; the phosphors shows an efficient bluish-green wide-band emission centred at 490 nm, which originates from the 4f(6)d(1) → 4f(7) transition of Eu(2+) ions. The excitation spectra of the phosphors have a band centred at 329 nm. It was also characterized by XRD, FT-IR for confirmation of phase purity, and FT-IR analysis indicated the vibrations of metal-oxygen (M-O) groups. SEM shows the morphology of the phosphor at the submicron scale. The results indicate that Ba3Al2O5Cl2:Eu(2+) phosphor may be applicable for solid-state lighting purposes.

Novel blue-emitting SrMg2Al16O27:Eu2+ phosphor for solid-state lighting.

Eu(2+)-activated SrMg(2)Al(16)O(27) novel phosphor was synthesized by a combustion method (550°C furnace). The prepared phosphor was first characterized by X-ray diffraction (XRD) for confirmation of phase purity. SEM analysis showed the morphology of the phosphor. The photoluminescence characteristics showed broad-band excitation at 324 nm, which was monitored at 465 nm emission wavelength. The SrMg(2)Al(16)O(27):Eu(2+) phosphor shows broad blue emission centred at 465 nm, emitting a blue light corresponding to 4f(6) 5d(1) → 4f(7) transition. Here we report the photoluminescence characteristics of the prepared phosphor and compare it with commercial BAM:Eu(2+) phosphor.

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.