White light emission characteristics of Tb3+ and Sm3+ co-doped CaYAlO4 nanocrystalline phosphors for solid-state lighting (original) (raw)
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Tb3+/Sm3+ ions co-doped Ca2La8(GeO4)6O2 (CLGO) phosphors are prepared by a pechini-type sol-gel technique. The nanocrystalline phosphors are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The photoluminescence emission and excitation spectra are measured for individually Tb3+, Sm3+ ions doped and Tb3+/Sm3+ ions co-doped phosphor samples. For the Tb3+/Sm3+ ions co-doped samples, we can observe emission covering the entire visible region with sharp peaks in green, orange, and red regions. As the Sm3+ ion concentration increases, the Commission International de I’Eclairage chromaticity coordinates shift towards warm white-light region due to the energy transfer from Tb3+ to Sm3+ ions. This energy transfer property is clearly visible in the emission spectra under 374 nm excitation.
Synthesis and luminescent properties of Tb3+ activated cadmium silicate nanophosphor
Journal of Alloys and Compounds, 2014
Optically efficient terbium activated alkaline earth metal tungstate nano phosphors (AWO 4 [A = Ca, Sr]) with different doping concentrations have been prepared by mechanochemically assisted solid state metathesis reaction at room temperature for the first time. The prepared phosphors were characterized by the X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), Fourier transform Raman (FT-Raman) spectroscopy, photoluminescence and diffuse reflectance spectroscopy measurements. The XRD and Raman spectra results showed that the prepared powders present a scheelite-type tetragonal structure. FTIR spectra exhibited a high absorption band situated at around 850 cm-1 , which was ascribed to the W-O antisymmetric stretching vibrations into the [WO 4 ] 2tetrahedron groups and the SEM images reveal that the particle sizes were in the range of 20-60 nm. The excitation and the emission spectra were measured to characterize the luminescent properties of the phosphors. The excitation spectrum exhibits a charge transfer broad band along with some sharp peaks from the typical 4f-4f transitions of Tb 3?. Under excitation of UV light, these AWO 4 :xTb 3? (A = Ca, Sr) phosphors showed a strong emission band centered at 545 nm (green) which corresponds to 5 D 4 ? 7 F 5 transition of Tb 3?. Analysis of the emission spectra with different Tb 3? concentrations revealed that the optimum dopant concentration for CaWO 4 :xTb 3? and SrWO 4 :xTb 3? phosphors are about 8 and 6 mol% of Tb 3?. The green emission intensity of the solid state meta-thesis prepared CaWO 4 :0.08Tb 3? and SrWO 4 :0.06Tb 3? phosphors are 1.5 and 1.2 times greater than that of the commercial LaPO 4 :Ce, Tb green phosphor. All properties show that AWO 4 :Tb 3? (A = Ca, Sr) is a very appropriate green-emitting phosphor for fluorescent lamp applications.
Optical Materials, 2017
Phosphors of CaLa 4 Si 3 O 13 singly-and co-doped with Ce 3þ and Tb 3þ , which are suitable for application in white LEDs, were successfully produced by using a high temperature solid state reaction method. Their apatite crystalline structure as well as their photoluminescent properties both at room temperature and at higher temperatures (up to 150 C) were experimentally determined, which also allowed the determination of the energy transfer efficiency and mechanism in the host lattice from the sensitizer Ce 3þ ions to the activator Tb 3þ ions. The excitation spectra of the doped phosphors exhibited an intense, broad band from 200 to 420 nm, which is a good match for the UV and near-UV chip (350e420 nm). Under excitation with UV light, two distinct luminescence bands were recorded; a blue one centered at 433 nm, which is typical for Ce 3þ emission, and a green one, which peaks at 552 nm, originated from 5 D 4 / 7 F 5 transition in Tb 3þ .
White‐ and blue‐light‐emitting dysprosium(III) and terbium(III)‐doped gadolinium titanate phosphors
Luminescence, 2016
Here we report the synthesis and structural, morphological, and photoluminescence analysis of white‐ and blue‐light‐emitting Dy3+‐ and Tm3+‐doped Gd2Ti2O7 nanophosphors. Single‐phase cubic Gd2Ti2O7 nanopowders consist of compact, dense aggregates of nanoparticles with an average size of ~25 nm for Dy3+‐doped and ~50 nm for Tm3+‐doped samples. The photoluminescence results indicated that ultraviolet (UV) light excitation of the Dy3+‐doped sample resulted in direct generation of white light, while a dominant yellow emission was obtained under blue‐light excitation. Intense blue light was obtained for Tm3+‐doped Gd2Ti2O7 under UV excitation suggesting that this material could be used as a blue phosphor.
Dy 3+-doped CaAl 12 O 19 phosphors were synthesized utilizing a combustion method. Crystal structure and morphological examinations were performed respectively using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques to identify the phase and morphology of the synthesized samples. Fourier transform infrared spectroscopy (FTIR) estimations were carried out using the KBr method. Photoluminescence properties (excitation and emission) were recorded at room temperature. CaAl 12 O 19 :Dy 3+ phosphor showed two emission peaks respectively under a 350-nm excitation wavelength, centered at 477 nm and 573 nm. Dipole-dipole interaction via nonradiative energy shifting has been considered as the major cause of concentration quenching when Dy 3+ concentration was more than 3 mol%. The CIE chromaticity coordinates positioned at (0.3185, 0.3580) for the CaAl 12 O 19 :0.03Dy 3+ phosphor had a correlated color temperature (CCT) of 6057 K, which is situated in the cool white area. Existing results point out that the CaAl 12 O 19 :0.03Dy 3+ phosphor could be a favorable candidate for use in white light-emitting diodes (WLEDs). KEYWORDS aluminate, concentration quenching, Dy 3 + , photoluminescence, WLEDs 1 | INTRODUCTION At the present time, the development of energy-saving lighting is an essential core interest for researchers. Large amounts of power can be saved by using efficient energy-saving light sources. Traditional incandescent and fluorescent lamps, with their resulting heat or gas release, have related colossal energy losses. [1] The use of energy proficient solid-state lighting appliances, for example compact fluorescent lamps (CFLs) and light-emitting diodes (LEDs), to deliver white light is an attractive alternative. Due to the above concern, the production of phosphors with excellent properties is an essential prerequisite. The efficacy of white light-emitting diodes (WLEDs) has surpassed that of incandescent lamps and fluorescent lamps. Due to their exceptional luminescence features, improved stability, energy-efficient nature, prominent luminescence efficiency, ecological amicability, and low cost, research into WLEDs has become more important. [2-4] WLEDs are mostly fabricated by applying three different techniques: (i) by making use of a mixture of red-green-blue (RGB) LEDs; (ii) through the utilization of ultraviolet (UV) LEDs to excite RGB phos-phors; and (iii) by employing blue LEDs to pump single-phase yellow or blended green and red phosphors. [1,5] At the present time, blue emitting chips combined with yellow phosphors (YAG:Ce 3+) are acknowledged as existing industrial WLEDs. Nevertheless, inferable from red light effect insufficiency, low color rendering index and high correlated color temperature (CCT) are commonly experienced by phosphors in this group. High CCT and low color rendering index (CRI) are not good factors when providing domiciliary or office lighting. This hindrance can be resolved by utilizing tricolor WLEDs dependent on red, green, and blue phosphors [6-8]. This purpose can be achieved by spreading these three phosphors on a transpicuous silicone that is then enclosed and then combined with blue or UV chips to excite the phosphors [1]. This factor is a major obstacle in field of materials science for the
Green Light Emitting Tb3+ Doped Phosphors - A Review
Material Science Research India, 2018
WLEDs were the potential materials for significantly improving lighting efficiency, resulting in reduction of the excitation energy and also reduction in pollution from fossil fuel power plants. To enhance the quality of white-light, the researches on single-component phosphor are very much essential. Green light emitting phosphors are widely used in solid state lighting technology. Tb3+ ions are doped into different hosts and they are excited by UV or NUV light to emit green light. This review presents, different hosts like silicates, oxides, phosphates and titanates based Tb3+ ions doped phosphor. Attempts were made to analyse preparation technique and photoluminescence characteristics of phosphors. Finally potential material among selected materials is identified for light emitting display device applications.
RSC Advances, 2022
The polychromatic phosphor with an apatite structure Ca 2 La 3 (SiO 4) 3 F:0.15Tb 3+ ,xSm 3+ (CLSOF:0.15Tb 3+ ,xSm 3+) was synthesized via a solid-state route. The phase and morphology of the phosphor has been investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The structures of the as-prepared phosphor were verified by means of the Rietveld method. The optical performance was investigated thoroughly and the phosphors could emit multicolor light from short wavelengths to long wavelengths by gradually increasing the doping contents of samarium. All the results support that the energy transfer in CLSOF:0.15Tb 3+ ,xSm 3+ contributes to the color tunable property of the phosphor. to generate red light when used as a phosphor activator, whereas terbium has the potential to emit green light when used as a phosphor sensitizer. 11-13 An apatite compound is oen selected to serve as the host because of its changeable crystal eld environment and its strong chemical stability, which is unaffected by the former. M 10 (XO 4) 6 Y 2 is the chemical formula for the apatite structural compound and M might serve as a monovalent cationusually an alkali metalbut also a trivalent cation like a lanthanide element, or even a divalent cation like an alkaline earth metal; X denotes S, Ge, Si, and P, among others; Y is most commonly shorthand for the element halogen and the element oxygen, both of which function as channel anions. 14-16 Compounds of apatite have been the subject of much research in a variety of elds and for several different usages. For instance, Sr 9-Gd(PO 4) 5 (SiO 4)F 2 , 17 Ba 2 La 3 (SiO 4) 3 F, 18 Ba 2 La 3 (SiO 4) 3 Cl, 19 etc. Considering that several single-phase multicolor phosphors may be generated via the transfer of energy between rare earth ions, structure regulation allows for the production of many variations that may be generated from the crystal structure of apatite, which has the potential to remarkably increase the variety of luminous materials and give other alternatives for the sector of solid-state lighting. However, as far as we are aware, there have been no reports concerning Ca 2 La 3 (SiO 4) 3 F (CLSOF) doped with samarium and terbium as of yet. We generated the Tb 3+ /Sm 3+ doped with Ca 2 La 3 (SiO 4) 3 F phosphor that features an apatite structure so that we could examine its structure as well as its luminescence characteristics, particularly the energy transmission. Adjustable phosphors in the colors green, yellow, orange, and red were produced by progressively modifying the doping ratio of rare earth ions. The host material remained unchanged during this process.
CaYAl 3 O 7 : Eu 3þ phosphor sample is synthesized through solid state method. The structural property of synthesized material is analyzed by using XRD patterns. The AFM image analysis shows the topography of samples with formation of nano-structure and spherical shape. The optical property of a sample is monitored by using 260 nm excitation sources. The dominant peak of red hue is found at 620 nm due to 5 D 0 / 7 F 2 manifold. The stability of samples is investigated for two different conditions by measuring photoluminescence emission spectra and time resolved spectroscopy. The CIE color co-ordinate diagram shows the emission of light in pure red region thus it may be potential candidate for single light emitting source in red regime.