The present paper reports synthesis and photoluminescence studies of cadmium tungstate (CdWO 4 ) and cerium-doped cadmium tungstate. The samples were synthesised by low cost and low temperature hydrothermal method and characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and photoluminescence analysis. XRD pattern reveals that the CdWO 4 has monoclinic wolframite structure. The FTIR spectrum of cerium-doped CdWO 4 exhibits broadband below 700 cm À1 which is due to the d (Ce-O-C) mode. The TEM images show that size of particle is approximately 60-120 nm in both samples. A broad intense peak was observed at 474 nm when the samples were excited with 263 nm. A broad intense peak was observed at 475 nm when the samples were excited with 600 nm. The intensity of the 474 nm peak decreases with increase in cerium doping concentration. The observation of 475 nm peak when excited with 600 nm is upconversion luminescence. This upconversion emission is due to energy transfer upconversion process involving Cd 2þ ions and [WO 6 ] 6À ions. Ce 3þ ion is responsible for the peak shift of 6 nm.

We report synthesis of a cerium-activated strontium pyrophosphate (Sr2 P2 O7 ) phosphor using a high-temperature combustion method. Samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) and thermoluminescence (TL). The XRD pattern reveals that Sr2 P2 O7 has an α-phase with crystallization in the orthorhombic space group of Pnam. The IR spectrum of α-Sr2 P2 O7 displays characteristic bands at 746 and 1190 cm(-1) corresponding to the absorption of (P2 O7 )(-4) . PL emission spectra exhibit a broad emission band around 376 nm in the near-UV region due to the allowed 5d-4f transition of cerium and suggest its applications in a UV light-emitting diode (LED) source. PL also reveals that the emission originates from 5d-4f transition of Ce(3+) and intensity increases with doping concentration. TL measurements made after X-ray irradiation, manifest a single intense glow peak at around 192°C, which suggests that this is an outstanding candidate for dosimetry applications. The kinetic parameters, activation energy and frequency factor of the glow curve were calculated using different analysis methods.

No abstract

The luminescence properties of Sr2GdTaO6 have been studied by keeping Eu(3+) as constant concentration and varying Er(3+) concentration. Sr2GdTaO6 phosphor doped with rare earth ions of Eu and Er having monoclinic phase of space group P21/n was synthesized, and their photoluminescence properties have been examined under UV excitation of wavelength 265 nm and 275 nm. PL emission exhibited around 468, 475, 580, 596, and 610 nm wavelength subsequently for various concentrations of Er(3+) for two different excitation wavelengths. By using xenon lamp as source and corresponding wavelength having excitation wavelength 265 and 275 nm, it is observed that the maximum light emission yield in region presenting a color-correlated temperature in the range of 1500-1900 K and 3000-6000 K.

Strontium pyrophosphate (Sr2P2O7) doped with various concentrations of Eu3+ as a doping agent is synthesized using a combustion method and to study the thermoluminescence dosimetry [TLD] and applications.