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Synthesis and characterization of a Dy3+-activated calcium yttrium oxide (CaY2O4) phosphor are reported. The CaY2O4:Dy3+ (1.5 mol%) phosphor is synthesized using a modified solid-state reaction technique for calcination and sintering. The cubic structure is revealed by the X-ray diffraction technique. The morphology and particle size distribution of the prepared phosphor are investigated by the FEGSEM technique. The chemical bonds and functional group analysis are confirmed by the FTIR. A photoluminescence analysis of the CaY2O4:Dy3+ phosphor shows dual excitation wavelengths at 285 and 348 nm, especially in the ultraviolet region. At 383 nm, three distinct emission peaks are found at the wavelengths 238, 485, and 571 nm. The spectroscopic parameters are calculated using the CIE chromaticity coordinates. The CIE coordinates of the Dysprosium ion-activated CaY2O4 phosphor (1.5 mol%) show an emission near the white light region of the chromaticity diagram, suggesting that it is suitable for W-LED applications. [ABSTRACT FROM AUTHOR]

Europium ion (Eu3+) doped lanthanum cerium phosphate is synthesized using the solid-state reaction method. Phase purity and morphology are assessed via XRD and SEM, respectively. The XRD analysis shows a monophasic crystalline structure with the average crystallite size of 87 nm. SEM images show a tablet-like morphology of phosphor. FTIR spectroscopy confirms the phosphor formation based on stretching, bending, and vibrational modes. The photoluminescence excitation spectrum demonstrates a broad excitation band centered at 277 nm, while emission spectra exhibit narrow luminescent bands at 469 and 544 nm, attributed to intracenter transitions of Eu3+. The thermoluminescence glow curve analysis is performed for the optimized doping ion concentration, and trap parameters are obtained using the computerized glow curve deconvolution technique. These investigations suggest the potential utility of the prepared phosphor for bluish-green emission in diverse display applications, while the trap analysis elucidates the formation of luminescence centers in Eu3+-doped phosphors. [ABSTRACT FROM AUTHOR]

The synthesis and the structural and luminescence studies of samarium-doped calcium aluminate phosphors are reported. These phosphors are synthesized by the solid-state reaction method with a variable concentration of doping ions (0.5–3.0 mol%). The synthesized phosphors are characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. The XRD studies show that the doped phosphors have a cubic structure. The SEM images reveal that the Sm3+- doped Ca3Al2O6 phosphor represents a combination of some rod-like and flower-like structures. The FTIR studies confirm the formation of a Ca3Al2O6:Sm3+ phosphor. The photoluminescence (PL) emission measurements upon excitation by 273 nm (ultraviolet light) show the characteristic emission peaks of Sm3+ at 579, 589, 600 and 619 nm. The characteristic orange-red emission is observed for samarium ion. The excitation spectra of the Ca3Al2O6:Sm3+ phosphor mainly consist of a more intense charge transfer band (CTB) of Sm3+ located at 273 and 395 nm with some peaks centred at 319 and 362 nm. The CIE coordinates are calculated by the spectrophotometric method using the spectral energy distribution of the Ca3Al2O6:Sm3+ sample. The prepared phosphors can act as a single host for orange-red light emission in display devices. [ABSTRACT FROM AUTHOR]

Synthesis and characterization of Eu3+-doped Er2SiO5 phosphor are reported. The samples are prepared using the modified conventional solid-state synthesis technique with variable concentrations of doping ions and their structural studies are carried out by X–ray diffraction (XRD). The information on the morphology of the samples prepared with optimized doping ion concentrations is obtained by scanning electron microscopy (SEM). A photoluminescence (PL) analysis of the phosphor samples is also done for the fixed doping ion concentrations. The identified PL emission bands are attributed to the intra 4f transitions of a Eu3+ ion, such as 5D0→7F1 at 590 nm, 5D0→7F0 at 602 and 5D0→7F2 at 613 nm. The corresponding transitions of the doping ions and the concentration quenching effect are studied in detail. The 1931 Commission Internationale de l'éclairage (CIE) (x, y) chromaticity coordinates show the spectral distribution calculated from the PL emission spectrum. A thermoluminescence (TL) glow curve analysis is performed for variable doping ion concentrations, and the corresponding trap parameters are calculated using the Computerized Glow Curve Deconvolution (CGCD) technique. Our study shows that as-prepared phosphor may be useful for display devices. [ABSTRACT FROM AUTHOR]

In this article, thermoluminescence (TL) and photoluminescence (PL) of Eu3+ doped La2Zr2O7 (LZO) phosphor with various concentrations were reported. A conventional solid-state reaction method was used for the preparation of phosphor. Boric acid is used as a flow and the materials are required for the formulation of phosphor with varying concentrations of Eu3+ (0.2 - 2 mol %) in Eu2O3, ZrO2, and La2O3. For the investigation of morphology, structural and luminescence properties of the sample, techniques used were X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectra (PL), thermoluminescence (TL), and Commission Internationale de I'Eclairage (CIE) chromaticity diagram. The results of the XRD analysis obtained for La2Zr2O7 :Eu3+ phosphors are disclosed average crystalline size (~38 nm) with its cubic crystal structure. The SEM images confirmed flaky morphology particle as well as connectivity with the grain. At the excitation of 395 nm, phosphor expressed many emission peaks at 591, 595, 615, and 626 nm, corresponding to the respective transitions 5D0 → 7FJ (J= 1-4) of Eu3+. The impact of the various doping concentration of europium on the photoluminescence properties of the sample was also discussed. During the recording of the TL glow curve, the heating rate used was 5°C s-1 for UV exposure of different doses. Here also discussed the consequences of various concentrations on TL intensity, where it's noticed that the intensity increased collinearly with increases in Eu3+ ion concentration, up to 1.5 mol %, and further decreased with increase in concentration. [ABSTRACT FROM AUTHOR]

[Display omitted] The LaCePO 4 :Dy3+ luminescence experiments revealed the excitation peak at 275 nm which gives the emission spectra in visible region with intensive peaks centered at 475 and 573 nm. The emission spectra showed the transition from 4F 9/2 to the ground energy state. The prepared phosphor may be useful for display applications in white light emission and thermoluminescence dosimeters. [ABSTRACT FROM AUTHOR]

[Display omitted] The experimental results of luminescence measurements in Ca 3 Al 2 O 6 : Tb showed single excitation wavelengths at 246 and 278 nm in the UV region. For the 278 nm excitation, six distinct emission peaks were found at 378, 419, 437, 447, 487 and 544 nm. Some spectroscopic parameters were calculated using CIE coordinates showing emission in the near-blue region, which may be useful for various display devices. [ABSTRACT FROM AUTHOR]

The near-infrared-to-visible upconversion luminescence behaviour of Er3+-doped CaZrO3 phosphor is discussed in this manuscript. The phosphor was prepared by a combustion synthesis technique that is suitable for less-time-taking techniques for nanophosphors. The starting materials used for sample preparation were Ca(NO3)2.4H2O, Zr(NO3)4 and Er(NO3)2, and urea was used as a fuel. The prepared sample was characterized by X-ray diffraction (XRD). The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM). The functional group analysis was determined by Fourier transform infrared (FTIR) spectroscopy. All prepared phosphors with variable Er3+ concentrations (0.5-2.5 mol%) were studied by photoluminescence analysis. It was found that the excitation spectra of the prepared phosphor showed a sharp excitation peak centred at 980 nm. The emission spectra with variable Er3+ concentrations showed strong peaks in the 555 nm and 567 nm range, with a dominant peak at 555 nm due to the (2H11/2,4S3/2) transition and a weaker transition at 567 nm associated with 527 nm. Spectrophotometric determination of the peak was evaluated by the Commission Internationale de I'Eclairage (CIE) method These upconverted emissions were attributed to a two-photon process. The excitation wavelength dependence of the upconverted luminescence, together with its time evolution after infrared pulsed excitation, suggested that energy transfer upconversion processes were responsible for the upconversion luminescence. The upconversion mechanisms were studied in detail through laser power dependence. Excited state absorption and energy transfer processes were discussed as possible upconversion mechanisms. The cross-relaxation process in Er3+ was also investigated. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Ce 3+ -doped CaAl 12 O 19 phosphors with different Ce 3+ contents, as well as those with Mg 2+ codoped powders, were successfully synthesized using a rapid combustion method (<5 min) for this paper. The powders were well characterized by the X-ray diffraction (XRD) and photoluminescence (PL) techniques. The emission measurements upon a UV-light excitation (262 nm) showed the emission characteristics of the Ce 3+ ion that are due to the 5d–4 f transitions. The emission and excitation spectra were recorded as the Ce 3+ concentration was kept constant and the Mg 2+ concentration was varied. It became evident that the addition of the Mg 2+ along with the Ce 3+ resulted in increases of the PL intensity, and the reasons for this behavior are discussed. [ABSTRACT FROM AUTHOR]

Yttrium aluminum perovskite (YAP) is a promising high temperature ceramic material, known for its mechanical, structural and optical properties. YAP’s also known as an ideal host material for solid-state lasers and phosphors. In this work, Ce 3+ doped YAlO 3 phosphors were synthesized by solid state reaction method, which is very suitable technique for large scale production. A prepared phosphor was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Photoluminescence spectra and Thermoluminescence (TL) glow curve study. The starting reagents used for sample preparation are Y 2 O 3 , Al 2 O 3 and CeO 2, boric acid used as a flux. Ratio of Y:Al was 1:1 which shows perovskite structure confirmed by the X-ray diffraction (XRD) study. The entire prepared sample was studied by PL excitation and emission spectra. Prominent peak at 446 nm (blue emission) which shows broad emission spectra of photoluminescence. It proves that prepared phosphor can act as a single host for blue emission of light and can be used for display applications. Commission Internationale de I’Eclairage (CIE) techniques proves the blue emission of light ( x = .148, y = .117). TL glow curve analysis of prepared phosphor shows the prominent peak at 189 °C for the variable UV exposure time and high temperature peak shows the more stability and less fading in the prepared phosphor. Kinetic data of prepared phosphor were evaluated by peak shape method for variable UV exposure time (5–25 min). [ABSTRACT FROM AUTHOR]

Cerium doped yttrium oxy-orthosilicate (Y 2 SiO 5 :Ce 3+ ) phosphor was synthesized by modified solid state reaction method, which is low cost and useful for large scale production. A sample was characterized by X-ray diffraction (XRD) technique as well as field emission gun scanning electron microscopy. The crystallite size was calculated by Scherer׳s formula. The effect of Ce 3+ concentration on photoluminescence studies was interpreted. The sample shows good PL spectra in the violet and blue region. The excitation spectra monitored at 400 nm and emission spectra monitored at 360 nm. The spectrophotometric determination was calculated by Commission Internationale de I’Eclairage technique. Using this phosphor, the desired CIE values including emissions throughout the violet (360 nm) and blue (427 nm) of the spectra were achieved. Efficient blue light emitting diodes were fabricated using Ce 3+ doped phosphor based on near ultraviolet (NUV) excited LED lights. [ABSTRACT FROM AUTHOR]

Gadolinium monoaluminate is successfully synthesized by the high solid state reaction method. The method is suitable for large scale production. The high temperature synthesis techniques have some advantages to enhance the efficiency of luminescence. Samples were prepared with variable concentration of europium (0.5–6 mol%) all the prepared sample were characterized by X-ray diffraction technique (XRD) and transmission electron microscopic (TEM) technique. The particle size was evaluated by Scherer’s formula and found around 55.16 nm and having orthorhombic phase. The surface morphology of prepared phosphor was determined by TEM and it shows good connectivity with grain and formation of nano sized crystal. The photoluminescence with variable concentration of europium shows very good excitation and emission spectra. The excitation spectra monitored at 612 nm excitation and excitation found with broad peaks at 266 nm with shoulder peak at 274 nm. The emission spectra monitored at 266 nm and it shows all peaks in visible region (583, 594, 599, 613 and 630 nm) with intense peak at 613 nm (red emission). The intensity of PL spectra increases with increasing the concentration of europium, up to 5 mol% after this concentration intensity decreases due to concentration quenching occurs. The spectrophotometric determination was determined by Commission Internationale de I’Eclairage (CIE) technique. [ABSTRACT FROM AUTHOR]

Phosphors with the composition La 1-x Gd x Al 11 O 18 (x = 0.01–0.10) were synthesized by combustion at a furnace temperature of 500 °C. The formation of the as-prepared combustion products was confirmed by X-ray diffraction analysis. On excitation with 273 nm, an emission band for the Gd 3+ ion was observed at 314 nm. This band progressively enhanced with increasing Gd 3+ concentration. The phosphor with low concentrations of Gd 3+ ions exhibits prominent ESR lines with g eff  ∼ 1.9, 2.0, 4.7, and 5.9. With high dopant concentrations, the spectrum shows features similar to those of a U-spectrum with dominant lines with g eff  ∼ 2.0, 2.9, 4.6, and 6.1. Low field lines arise from distortions in the immediate environment of the Gd 3+ ion. [ABSTRACT FROM AUTHOR]

A successful preparation of a Tb 3+ -doped LiBaB 9 O 15 phosphors was achieved through the use of a solution-combustion method. The preparation of the powders of the Tb 3+ -doped LiBaB 9 O 15 phosphor was confirmed by X-ray diffraction (XRD) results; furthermore, the size and morphology of these powders were further examined using a scanning electron microscope (SEM). A study of the luminescent proprieties under a UV excitation showed a dominant and strong green luminescent peak at 542 nm that is due to the d–f transition. When monitored at 542 nm, the excitation spectrum exhibited a broad band centered at 230 nm and several weak peaks in the wavelength range of 300–400 nm that are attributed to the f-d transitions and the intra-4f-4f transitions of the Tb 3+ ions, respectively. The addition of the Tb 3+ concentration greatly improved the photoluminescent properties of the present phosphors, and the Commission International de I’Eclairage (CIE) chromaticity coordinates are located in the green region. The present study suggests that the potential applications of the Tb 3+ -doped LiBaB 9 O 15 phosphors might be in the lighting and display fields. [ABSTRACT FROM AUTHOR]

The solid state reaction technique was used to successfully produce Yttrium Zirconate Y2Zr2O7:Gd3 +doped phosphors at 13500 C for 3 h. X-ray diffraction (XRD) and scanning electron microscopy were used to examine the structure and morphology. At room temperature, thermoluminecsence qualities were measured by irradiating with UV-radiate at a heating rate of 50 Cs-1, reaching a peak at 1940 C. Chen's glow peak approach was used to determine kinetic parameters such as activation energy, frequency factor, and trap depth, and the results are presented in detail. The results show that the synthesised phosphors are a procurement of materials for dosimetric applications. [ABSTRACT FROM AUTHOR]