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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]

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]

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]

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]

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]