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The synthesis and characterization of Dy3+-activated CaSi2O5 phosphor is reported. The phosphors were synthesized using a modified solid-state reaction method with variable concentrations of doping ions (0.1–2.5 mol.%) of Dy3+. The synthesized phosphors were characterized by X-ray diffraction (XRD) analysis and the field emission scanning electron microscopy (FESEM) technique. The XRD pattern revealed that the doped phosphors had a cubic structure. FESEM micrographs clearly indicated that the particles crystallized in inhomogeneous morphology on a micrometer scale with a sporadic and asymmetrical shape. Photoluminescence excitation and emission spectra were monitored for variable doping concentrations and the emission found at 485 and 576 nm (excited at 353 nm). The corresponding transitions of the doping ion and concentration quenching effect were studied in detail. The 1931 CIE (x, y) chromaticity coordinates (x = 0.30 and y = 0.31) showed the distribution of a spectral region calculated from PL emission spectra. On the basis of CIE analysis, the prepared phosphor is useful for white light emission in inorganic light-emitting diodes. As-synthesized phosphor was examined by thermoluminescence glow curve analysis with different doses of gamma and electron beam and corresponding kinetic parameters were calculated using the computerized glow curve deconvolution technique. [ABSTRACT FROM AUTHOR]

A series of Tb3+-doped Li2CaSiO4 phosphors were prepared by high-temperature solid-state reaction method. The structural studies were done using the X-ray diffraction (XRD) technique. The XRD patterns revealed that the sample was monophased and crystallizes in a cubic structure. Scanning electron microscopy (SEM) was used to obtain information about the morphology of the prepared samples. SEM micrographs clearly indicated that the particles crystallized in inhomogeneous morphology, with the particle size ranging from 1 μm to 100 nm. Also, photoluminescence (PL) analysis of the phosphor samples for different concentrations of doping ions with variable excitations were presented. The PL excitation spectrum of Tb3+ ion-doped Li2CaSiO4 has many sharp peaks, mainly at 418 nm (5D3 → 7F5), 436 nm (5D3 → 7F4), 456 nm (5D3 → 7F3), 472 nm (5D3 → 7F2,1,0), 487 nm (5D4 → 7F6), 550 nm (5D4 → 7F5), and 590 nm (5D4 → 7F4), assigned to the transitions of Tb- ion respectively (excited at 237 nm). The 1931 CIE (x, y) chromaticity coordinates showed the distribution of the spectral region calculated from PL emission spectra, and found to be (0.19, 0.22) in a bluish-green region of Tb3+ (0.01 wt (in grams)) Li2CaSiO4 phosphor. Our study shows that as-prepared phosphor may be useful for optical devices, mainly for LEDs, as a bluish-green component. [ABSTRACT FROM AUTHOR]

We present new aspects of erbium- or ytterbium-doped pure gadolinium oxide (Gd2O3:Er3+/Yb3+) as a suitable candidate for drug delivery and magnetic resonance (MR) applications. The samples were prepared using the conventional sol–gel synthesis technique. The structural studies revealed that the prepared sample was monophased and crystallizes in a cubic structure. FTIR measurements confirmed the creation of Gd2O3:Er3+/Yb3+ phosphor. SEM micrographs clearly indicated that the particles crystallized in uniform shape, exhibiting nano-rod formation, with the particle size ranging from 55 to 5 nm. TEM images revealed that Er3+- and Yb3+-co-doped Gd2O3 nanoparticles were the collection of the nano-rods 2–4 nm thick and 18–20 nm long. Also, photoluminescence analysis of the phosphor samples for variable concentrations of doping ions was presented. When doped with Er3+/Yb3+, nano-rod Gd2O3 emits intense green emission and some red emission peaks, under a 980-nm near-infrared laser. Our study shows that as-prepared samples may be useful for optical imaging systems and that nano-rod formation may be used as a major host carrier for drug delivery. [ABSTRACT FROM AUTHOR]

Y2Sr3B4O12 phosphors doped with europium ions were synthesized by a modified conventional solid-state reaction method. Characterizations of the prepared samples, viz., X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL), and Commission Internationale de I'Eclairage were studied. The XRD analysis confirmed the formation of mixed phase due to polyborate and has a hexagonal crystalline yttrium orthoborate phosphor. SEM images showed the irregular morphology of the sample. The grain size distribution was broad and the average size was found to range from 2 μm to 100 nm. PL measurements showed excitation and emission characteristics of the prepared phosphor with different concentrations of the doping ion. From the emission spectra, it was clearly observed that the emission intensity of the magnetic dipole was higher than that of electric dipole transition owing to the Eu3+ ions occupying a higher symmetry site in the Y2Sr3B4O12 host. The intensity of PL increased with increasing concentration of the doping ion up to 2.0 mol.%; after that, the PL intensity decreased owing to the concentration-quenching phenomenon. The results indicated that Y2Sr3B4O12:Eu3+ phosphors can be selected as a potential candidate for solar cell/photovoltaic application. [ABSTRACT FROM AUTHOR]

The synthesis and luminescence analysis of Tb3+-activated phosphors were reported. Y2SiO5 phosphors were synthesized by a modified solid-state reaction method with a variable doping concentration of Tb3+ ion (0.5–2.5 mol.%). As synthesized, the phosphors were characterized by X-ray diffraction (XRD) analysis. The XRD pattern confirmed the monoclinic structure of the prepared phosphor. Scanning electron microscopy and High-Resolution Transmission Electron Microscopy (HRTEM) studies revealed nearly uniform particle size distribution in the prepared phosphors. The photoluminescence excitation spectra of the Y2SiO5:Tb3+ (0.5–2.5 mol.%) phosphor displayed one broad, intense peak at 258–277 nm. When excited at the 258 nm wavelength, the phosphors showed emission peaks at 553 nm (5D4 → 7F5), 544 nm (5D4 → 7F5) and 489 nm (5D4 → 7F6). The 1931 CIE (x,y) chromaticity coordinates showed the distribution of the spectral region calculated from the photoluminescence emission spectra. The values of x = 0.25 and y = 0.46 were very close to light green emission. Therefore, the prepared phosphor is very useful for light-emitting diode (green component) applications. [ABSTRACT FROM AUTHOR]

We discuss new features of Sm3+-doped LaCePO4 phosphor as a potential candidate for display applications. Mainly, the traditional modified solid-state synthesis technique was used to prepare the samples. The X-ray diffraction technique was used for the structural studies. LaCePO4:Sm3+ phosphor production was verified by Fourier transform infrared studies. It was customary to use scanning electron microscopy to learn more about the morphology of the prepared samples. Additionally, photoluminescence (PL) analysis of the phosphor samples was presented for different doping ion concentrations with various excitations. In the presence of Sm3+, LaCePO4 emits powerful blue and orange emissions. In-depth research was carried out on the transitions between the concentration quenching effect and the doping ion. The distribution of the spectral region estimated from PL emission spectra was shown in the 1931 Commission International de l'Éclairage (x, y) chromaticity coordinates and was located (0.20, 0.22) in the blue region. According to our research, as-prepared phosphor may find useful application in display devices, especially because of its blue and orange content. [ABSTRACT FROM AUTHOR]

Li2CaSiO4:Eu3+ phosphors with single phase were successfully synthesized by the solid state reaction method. Characterizations XRD, SEM, FTIR, Photoluminescence and CIE were studied of the prepared samples. SEM images showed irregular, non-homogeneous morphology and relatively big grain size of the samples. From the FTIR, it was observed that most of the bands are due to ligand ions (Ca–O, Si–O, Li–O) stretching or bending vibrations. The authors are interested in investigating the concentration effect of the activator ion in the host and also in the effect of the excitation wavelength on emission intensity of the synthesized phosphors. The experimental results of Li2CaSiO4:Eu3+ showed the different excitation wavelengths in the range 200–500 nm, especially in the ultraviolet region. Strong and sharp excitation peak was observed at 394 nm. The emission in the red spectrum and the CIE Chromaticity coordinate (0.68, 0.31) indicated that the phosphor has great potential in UV chip pumped white LEDs. A comparative investigation of the excitation and emission intensities of Li2CaSiO4:Eu3+ were studied. The CIE study of Li2CaSiO4:Eu3+ under the excitation of 394 nm was also studied. The CIE Chromaticity coordinates (0.68, 0.31) and (0.60, 0.39), (0.60, 0.38) indicated orange/red color. They are useful for the generation of white light for ultra-violet (394 nm) chip when pumped and multi-phosphors are converted into white LEDs. [ABSTRACT FROM AUTHOR]