Gd₂O₃: A Luminescent Material

Luminescence behavior of the Gd2O3 phosphor is one of the important aspects in the technology of rare earth-based inorganic phosphor materials. The structural and optical behavior of a Gd2O3 nanophosphor will be discussed in detail. Structural characterization of the Gd2O3 was carried out via X-ray diffraction and electron microscopy methods. To detail the photoluminescence behavior, the excitation and emission spectra were recorded and discussed. Thermoluminescence (TL) study and kinetic analysis of the UV- and gamma-irradiated phosphor were also carried out to determine the use of the phosphor for the dosimetric application. Tunned glow peaks were deconvoluted by applying glow curve deconvolution function, and all the trapping parameters were determined

Combustion synthesis and upconversion luminescence properties of Er3+, Yb3+ doped gadolinium oxide nanophosphor

Gd2O3: Er3+, Yb3+ Nanophosphor prepared by combustion synthesis method.  Optical and Upconversion luminescence properties of rare earth doped nanophosphors were studied. The nanophosphors were characterized using Scanning electron microscopy, X-ray diffraction and ultraviolet–visible absorption spectroscopy. The results of XRD show cubic phase can be obtained, the average crystalline size could be calculated as 38 and 49nm respectively, which coincided with the results from SEM images. The UV- Vis optical spectra were also studied. Upconversion luminescence spectra of samples under the range of 980 nm, excitation were investigated. The strong red and weak green emission was observed. The possible upconversion luminescence mechanisms for Er3+, Yb3+ doped gadolinium nanophosphor were also discussed

Effect of firing temperature on the particles size of Gd2O3: Eu doped nanophosphors

The paper reports that synthesis and characterization of Eu2+ doped Gd2O3 nanophosphors prepared by combustion synthesis. It has been reported that the effect of synthesis temperature on particle size dependence phenomenon of rare earth doped nanophosphors. The sample was characterized by XRD pattern and FTIR study. Synthesized sample shows cubic structure verified by the XRD results.  Size of the particle was caculated by scherer equation the avarage size obtained 15, 23 and 55 at 4000C, 5000C and 6000C respectively. In this synthesis urea used as a fuel for created reducing atmosphere during sample preparation.&nbsp

Synthesis, structural characterization and thermoluminescence glow curve study of gadolinium-doped Y2O3 nanophosphor

AbstractGadolinium-doped Y2O3 nanophosphor was synthesized by a solid-state reaction method, which could be used for large-scale production of phosphors. The structure of the phosphor sample was characterized by powder X-ray diffraction, field emission gun scanning electron microscopy and high-resolution transmission electron microscopy. The particle size was calculated from Scherer's formula. X-ray diffraction showed a grain size of 35–55nm, in good agreement with the scanning electron microscopy image. The synthesized sample showed good morphology and connectivity, with grains and formation of a nano-sized prepared sample. The diffraction pattern was measured by transmission electron microscopy with a selected area diffraction pattern. The prepared phosphor was also examined by thermoluminescence; to record the glow curve, 1mg phosphor was irradiated with ultraviolet at 254nm at a fixed heating rate of 7°Cs−1. The sample showed a well-resolved peak at 99°C for 1mol% of Gd3+. A lower temperature peak showed less stability and more fading of the prepared sample. A thermoluminescence glow curve gives information about trapping parameters such as activation energy and trap depth, order of kinetics and frequency. All the kinetics were calculated by the peak shape method

Thermoluminescence glow curve for UV induced ZrO2:Ti phosphor with variable concentration of dopant and various heating rate

The present paper reports the synthesis and characterization of Ti doped ZrO2 nanophosphors. The effects of variable concentration of titanium on thermoluminescence (TL) behaviour are studied. The samples were prepared by combustion a synthesis technique which is suitable for less time taking techniques also for large scale production for nano phosphors. The starting material used for sample preparation are Zr(NO3)3 and Ti(NO3)3 and urea used as a fuel. The prepared sample was characterized by X-ray diffraction technique (XRD) with variable concentration of Ti (0.05–0.5 mol%) there is no any phase change found with increase the concentration of Ti. Sample shows cubic structure and the particle size calculated by Scherer's formula. The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM) technique for optimized concentration of dopant. The good connectivity with grains and the semi-sphere like structure was found by FEGSEM. The functional group analysis was determined by Fourier transform infrared (FTIR) spectroscopic techniques. The prepared phosphor examined by thermoluminescence technique. For recording TL glow curve every time 2 mg phosphor was irradiated by UV 254 nm source and fixed the heating rate at 5 °C s−1. Sample shows well resolved peak at 167 °C with a shoulder peak at 376 °C. The higher temperature peak shows the well stability and less fading in prepared phosphor. Also the effect of Ti concentration at fixed UV exposure time was studied. The effect of UV exposure time and dose versus intensity plot was studied. Sample shows linear response with dose and broaden peak with high temperature shows the more stability and less fading in TL glow curve. The linear dose response, high stability and less fading phenomenon shows the sample may be useful for thermoluminescence dosimetry application. Trapping parameters are calculated for every recorded glow curve. The prepared phosphor with optimized concentration of dopant was studied for various heating rate method. The various heating rate (3 °C s−1 to 5 °C s−1) shows shifting in TL glow peaks at higher temperature side. That is opposite behaviour shows in TL glow curve with various heating rate method. The presence of transition metal ions changes (Ti) the TL glow curve structure either enhancing or quenching the TL efficiency. These changes are a consequence of the crystalline field perturbation due to the different characteristics of the dopant ions which supposedly replaces the Zr4+ sites. The traps and the glow curve structure are also dependent upon the morphology of the surface area which in turn depends on the nanocrystallite size. The nanocrystallite size depends also on the dopant ion. Furthermore, the obtained experimental results show that the presence of dopant ions also modifies the TL recombination efficiency which was found to be different for each irradiation type and the specific exposed material. It is important to notice that using the right dopant concentration, it is possible to maximize the TL efficiency and improve sensitivity and dose linearity for a specific irradiation type. For dual TL glow curve present in the sample it is very difficult to calculate the kinetic parameters from peak shape method. The kinetic parameters are calculated by (Computerized glow curve convolution technique) CGCD technique. Keywords: Thermoluminescence, ZrO2:Ti, Combustion synthesis, CGCD, Effect of dopant concentration, Various heating rat

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

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

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 5.1 eV. 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 0.82–2.24 eV. The frequency factor is of the order of between of 1.78 × 1012 and 9.84 × 1020 s−1. Keywords: Y2O3:Gd3+, XRD, SEM, Thermoluminescence, Gamma ray, CGC

Suitability of leaching test methods for fly ash and slag: A review

Fly ash and slag leachate pollution can be of great environmental concern due to generation of these wastes in huge quantities from their respective industrial units, mainly coal-based thermal power plants and iron and steel plants. For simulation of natural leaching in laboratory, various leaching methods are available, but selection of a method that can exactly simulate the real-life scenario for accurate estimation of various pollutants is challenging; particularly, the heavy metals present and impact due to reuse or disposal of these wastes. For choosing the most suitable leaching method according to specific situation, one must primarily consider the chemical and physical properties of wastes, the composition of the source, age of waste disposal, and the climatic conditions of the disposal area. Since these factors may not be specified, a variety of leaching methods with relevant equipment have been proposed by researchers; that are based on their required information to particular conditions in absence of a prescribed protocol and non standardization of equipment. The present review is an attempt to investigate the suitable leaching method for coal fly ash and slag