Kanchan Upadhyay

Photoluminescence behavior of ZrO2: Eu3+ with variable concentration of Eu3+ doped phosphor

Abstract The ZrO2 phosphor doped with Eu3+ was synthesized by solid state reaction method which is suitable for large scale production, and high temperature synthesis method. The prepared nanoparticles of ZrO2 phosphor was characterized by X-ray diffraction technique (XRD) for Structural analysis and field emission gun scanning electron microscopy (FEGSEM)) for morphological details. The optical behavior of the prepared phosphor was determined by photoluminescence (PL) spectra recorded in room temperature. The PL excitation spectra was found at 311 nm range and the emission spectra in the range of 400–650 nm.

Gamma ray induced thermoluminescence studies of yttrium (III) oxide nanopowders doped with gadolinium

Abstract Y2O3:Gd3+ nanophosphor was prepared by the solid state reaction method. Systematic studies have been done to investigate the structural and optical properties of the gadolinium doped Y2O3 phosphor. The prepared phosphor was characterized by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy and UV–VIS–NIR spectrophotometer. The XRD patterns reveal that these prepared phosphors have cubic phase crystal structure. SEM and TEM images showed uniform doping of the material over the entire materials. The energy band gap for gadolinium doped Y2O3 phosphor was revealed from the optical studies and was found to 5.1eV. The prepared phosphors were also examined by thermoluminescence technique. The kinetic parameters like trap depth, frequency factor were calculated by using the Peak shape method, which are discussed in details. The TL Glow curves were fitted in CGCD (computerized glow curve convolution deconvolution) technique & trapping parameters calculated. The TL parameters such as activation energy for deconvoluted peak were found in the range of 0.82–2.24eV. The frequency factor is of the order of between of 1.78×1012 and 9.84×1020s−1.

Synthesis and thermoluminescence behavior of ZrO2:Eu3+ with variable concentration of Eu3+ doped phosphor

Abstract Cubical ZrO2 phosphor doped with the europium synthesized by conventional solid state synthesis method. The prepared phosphor was characterized by X-ray diffraction (XRD) technique, field emission gun scanning electron microscopy (FEGSEM) and transmission electron microscopy (TEM). In this paper, we focused on the thermoluminescence glow curves and kinetic parameters, activation energy, order of kinetics, and the frequency factor of ZrO2:Eu3+ phosphor under different doses of UV irradiations at a heating rate of 6.7°C/s. The kinetic parameters activation energy E, the order of kinetics b, and the frequency factor s of synthesized phosphor of ZrO2:Eu3+ have been calculated by using a peak shape method.

Effect of annealing temperature on thermoluminescence glow curve for UV and gamma ray induced ZrO2:Ti phosphor

Abstract The present paper reports the thermoluminescence (TL) properties of combustion synthesized Ti doped ZrO2 nanophosphors the effect of annealing on TL glow curve was also studied. The structural characterizations were done by X-ray diffraction technique (XRD), composition by Fourier transformation infrared spectroscopy and surface morphology was determined by field emission gun scanning electron microscopy (FEGSEM) technique. The prepared phosphor annealed at 600 °C, 700 °C, 800 °C and 900 °C and its thermoluminescence glow curve were recorded. The heating rate effect, the thermal quenching as well as the annealing temperature of the material were optimized for the TL glow curve of the sample. The TL glow curves for different UV, gamma doses and for Ti concentration were studied. The TL glow curve of prepared samples have glow peak at 173 °C. The kinetic parameters was calculated by Computerized glow curve convolution technique (CGCD) technique. Fading and reusability studies of the nanophosphor further confirmed the phosphors suitability for radiation dosimetry. The main conclusion is that Solution Combustion Synthesis is one of the appropriate method for synthesis of Ti doped ZrO2 nanophosphors, which is suitable for temperature sensing applications, the post-synthesis annealing regime being one of the parameters that can affect the intensity and other parameters.

Effect of annealing on down-conversion properties of monoclinic Gd2O3:Er3+ nanophosphors.

Erbium-doped nano-sized Gd2O3 phosphor was prepared by a solution combustion method in the presence of urea as a fuel. The phosphor was characterized by X-ray diffractometry (XRD), Fourier transform infra-red spectroscopy, energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM). The results of the XRD shows that the phosphor has a monoclinic phase, which was further confirmed by the TEM results. Particle size was calculated by the Debye-Scherrer formula. The erbium-doped Gd2O3 nanophosphor was revealed to have good down-conversion (DC) properties and the intensity of phosphor could be modified by annealing. The effects of annealing at 900°C on the particle size and luminescence properties were studied and compared with freshly prepared Gd2O3:Er(3+) nanoparticles. The average particle sizes were calculated as 8 and 20 nm for the freshly prepared samples and samples annealed at 900°C for 1 h, respectively. The results show that both freshly prepared and annealed Gd2O3:Er(3+) have monoclinic structure.

TL glow curve analysis of UV, beta and gamma induced limestone collected from Amarnath holy cave

Abstract The paper reports themoluminescence glow curve analysis of UV (ultraviolet), β (beta) and γ (gamma) induced limestone collected from Amarnath holy cave. The collected natural sample was characterized by X-ray diffraction (XRD) technique and crystallite size calculated by Scherers formula. Surface morphology and particle size was calculated by transmission electron microscopy (TEM) study. Effect of annealing temperature on collected lime stone examined by TL glow curve study. The limestone was irradiated by UV radiation (254 nm source) and the TL glow curve recorded for different UV exposure time. For beta irradiation Sr90 source was used and is shows intense peak at 256 °C with a shoulder peak at higher temperature range. For gamma radiation Co60 source and TL glow curve recorded for different doses of gamma. The kinetic parameters calculation was performed for different glow curve by computerized glow curve deconvolution (CGCD) technique. The chemical composition of natural limestone was analyzed by energy dispersive X-ray spectroscopy (EDXS).

The down conversion properties of a Gd2O3:Er3+ phosphor prepared via a combustion synthesis method

Er3+ doped Gd2O3 phosphors were prepared via solution combustion synthesis method. Structural characterization and the luminescence behaviour of the prepared phosphors were determined and compared. The average crystal size for the phosphors yielded was in the nanometre range, which was calculated using XRD and confirmed by SEM and TEM techniques. Compositional analysis was carried out using FTIR. Qualitative and quantitative information regarding the powder sample were measured using EDX spectroscopy. The EDX and FT-IR spectra confirm the Er3+ element was present in the Gd2O3:Er3+ phosphors. For the photoluminescence studies the emission spectra were recorded under excitation at 275 nm. All the phosphors give emission peaks in the visible region. The effect of annealing and the Er3+ concentration on the emission spectra was studied for the prepared phosphors. The specific colours produced by the prepared phosphors were determined using the CIE chromaticity technique. The emitted coloured was tuned by determining the CIE coordinates for different concentrations of Er3+.

The effect of annealing and irradiation dose on the thermoluminescence glow peak of a monoclinic Gd2O3:Yb3+ phosphor

A monoclinic Gd2O3:Yb3+ phosphor was prepared using the combustion synthesis method. This study is mainly centered on the thermoluminescence behaviour of this monoclinic Gd2O3:Yb3+ phosphor. TL glow curves were recorded for two different irradiations, UV and gamma irradiation. The effect of annealing temperature, irradiation dose and Yb3+ concentration on thermoluminescence behaviour is studied. Computerized glow curve deconvolution (CGCD) was applied using the peak fit method on the TL glow curve for optimized conditions. Kinetic parameters were calculated for the optimized TL glow curve as well as for the deconvoluted glow curve. The activation energy calculated for the gamma irradiated samples is greater than the UV irradiated samples, which is due to the deeper traps formed by gamma irradiation.

Infrared spectroscopy and luminescence spectra of Yb3+ doped ZrO2 nanophosphor

Abstract The present paper reports infrared spectroscopy and luminescence spectra of Yb3+ doped ZrO2 nanophosphor. Sample was prepared by combustion synthesis method (CSM) for the variable concentration of ytterbium. The low temperature synthesis method was suitable for large scale production present method is an eco-friendly method as well as less time taking method as compared to other methods. The synthesized samples were characterized by X-ray diffraction (XRD) technique; scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) technique. The crystal size was calculated by Scherers formula. The particle size distribution in prepared sample was determined by SEM and TEM study. The photoluminescence spectra was recorded under the 980nm laser excitation with the variable concentration of ytterbium. Here the PL intensity increases with increasing the concentration of ytterbium. No concentration quenching were observed. The PL emission spectra shows intense emission peaks at 987, 998 and 1021nm all in infrared regions.

Structural Characterization of Gd 2 O 3 Phosphor Synthesized by Solid-State Reaction and Combustion Method Using X-Ray Diffraction and Transmission Electron Microscopic Techniques

The combustion synthesis and conventional solidstate reaction method was used to synthesize Gadolinium oxide (Gd2O3) phosphor. Nanoranged Gd2O3 was successfully synthesized by ignition of gadolinium nitrate followed by combustion in the presence of urea, and for the solid-state reaction method, boric acid was used as a flux at high temperature of 1400°C monoclinic and cubic phase gadolinium oxide (Gd2O3) phosphor was obtained for combustion and solid-state reaction method, respectively. Samples prepared by both the methods were characterized by using X-ray diffraction (XRD) spectroscopy, and transmission electron microscopy (TEM). The crystallite size and grain size of these phosphors are compared by using XRD profile analysis as well as by TEM. Other physical parameters such as strain, stress, and deformation energy density are also estimated precisely for the prominent XRD peaks of Gd2O3 powder in the range 2θ by using a modified Williamson-Hall analysis assuming uniform deformation model.