Fabrication and characterization of Gd2O2SO4:Tb3+ phosphors by sol-gel method (original) (raw)
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Synthesis and characterization of Gd2O2 S: Tb3+ phosphor powder for X-ray imaging detectors
2019
Gadolinium oxysulfide phosphor doped with trivalent terbium have been synthesized using urea homogenous precipitation and followed by sulfurization at 800 °C under argon atmosphere. Structural and morphological of synthesized phosphor powder were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FT-IR). Hexagonal structure of Gd2O2S:Tb3+ phosphor was confirmed by XRD. Compositional analysis were carried out by energy dispersive x-ray (EDX) and particle induced x-ray emission (PIXE). Photoluminescence emission spectra was measured by fluorescent spectrometer. A sedimentation technique is used to deposit the phosphor powder directly on the glass substrate using poly vinyl alcohol as a paste. A number of phosphor layers have been synthesized with the layer thickness ranging from 150 to 268 µm. Measurement results of x-ray conversion efficiency for layers were investigated using 300 kVp X-ray tube in which the maxim...
Acta Physica Polonica A, 2017
Scintillation materials are widely used in digital X-ray imaging applications, radiotherapy applications coupled with suitable photoreceptors. Gd2O2SO4 (GOS) scintillator doped with trivalent praseodymium (Pr 3+) presented high X-ray absorption properties and good spectral compatibility which were utilized extensively for imaging system of X-ray microscopy, soft X-ray phosphor screen for water window. In this study, GOS:0.01Pr 3+ scintillation material was synthesized by unique sol-gel process which was not previously applied and its characterization properties were investigated. Structure and luminescence properties of GOS:Pr 3+ were optimized by utilizing X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and luminescence spectroscopy.
Optical Materials 27 (2004) 559–565, 2004
Abstract: Terbium activated gadolinium oxysulphide phosphor (Gd2O2S:Tb) shows bright green luminescence and high efficiency under X ray excitation. Phosphor utilisation depends on powder characteristics and luminescence properties that are regulated during the synthesis stage. The paper presents some of our new results on the synthesis of Gd2O2S:Tb phosphor by solid-state reaction route from oxide precursors. Efficient luminescent powders utilisable in the manufacture of X-ray intensifying screens for medical diagnosis were prepared from optimised synthesis mixtures containing oxide precursors, alkaline carbonate based flux, alkaline phosphate based mineralising additives and sulphur suppliers.
Journal of Physics: Conference Series
Rare earth activators are impurities added in the phosphor material to enhance probability of visible photon emission during the luminescence process. The main activators employed are rare earth trivalent ions such as Ce +3 , Tb +3 , Pr 3+ and Eu +3. In this work, four terbium-activated Gd 2 O 2 S (GOS) powder screens with different thicknesses (1049 mg/cm 2 , 425.41 mg/cm 2 , 313 mg/cm 2 and 187.36 mg/cm 2) and one europium-activated GOS powder screen (232.18 mg/cm 2) were studied to investigate possible applications for general radiology detectors. Results presented relevant differences in crystallinity between the GOS:Tb doped screens and GOS:Eu screens in respect to the dopant agent present. The AE (Absolute efficiency) was found to rise (i) with the increase of the X-ray tube voltage with the highest peaking at 110kVp and (ii) with the decrease of the thickness among the four GOS:Tb. Comparing similar thickness values, the europium-activated powder screen showed lower AE than the corresponding terbium-activated.
Terbium activated gadolinium oxysulphide phosphor (Gd 2 O 2 S:Tb) shows bright green luminescence and high efficiency under Xray excitation. Phosphor utilisation depends on powder characteristics and luminescence properties that are regulated during the synthesis stage. The paper presents some of our new results on the synthesis of Gd 2 O 2 S:Tb phosphor by solid-state reaction route from oxide precursors. Efficient luminescent powders utilisable in the manufacture of X-ray intensifying screens for medical diagnosis were prepared from optimised synthesis mixtures containing oxide precursors, alkaline carbonate based flux, alkaline phosphate based mineralising additives and sulphur suppliers.
IEEE Transactions on Nuclear Science, 2011
The aim of the present study was to investigate the imaging transfer characteristics and the luminescence efficiency (XLE) of Gd2O2S:Eu powder scintillator for use in X-ray mammography detectors. Gd2O2S:Eu emits in the red part of the visible spectrum, having very good spectral compatibility with optical sensors employed in digital imaging systems. Three Gd2O2S:Eu powder scintillating screens, with coating thicknesses 33.1, 46.4 and 63.1 mg/cm2 , were prepared in our laboratory. The imaging performance of these screens was assessed by experimental determination of the modulation transfer function (MTF), the noise transfer function (NTF) and the detective quantum efficiency (DQE) as well as a single index image quality parameter such as the information capacity (IC). A theoretical model, describing radiation and light transfer, was used to fit experimental MTF data. This has allowed the estimation of optical attenuation coefficients of the scintillator. In addition, a previously validated Monte Carlo code, based on the X-ray attenuation properties and on the Mie light scattering theory, was used to estimate the X-ray detection efficiency, the Swank factor and the zero frequency DQE of the Gd2O2S:Eu scintillator. Results showed that Gd2O2S:Eu exhibits high MTF and DQE values, which are comparable to those of a commercially employed Gd2O2S:Tb screen. In addition Gd2O2S:Eu shows high compatibility (effective gain) to CCDs and to recently introduced CMOS based detectors. Considering our image quality parameters and luminescence efficiency results, this material can potentially be considered for use in digital X-ray mammography detectors.
Evaluation of Gd2O2S:Pr granular phosphor properties for X-ray mammography imaging
Journal of Luminescence, 2016
Gadolinium oxysulfide phosphor doped with trivalent terbium have been synthesized using urea homogenous precipitation and followed by sulfurization at 800 °C under argon atmosphere. Structural and morphological of synthesized phosphor powder were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FT-IR). Hexagonal structure of Gd 2 O 2 S:Tb 3+ phosphor was confirmed by XRD. Compositional analysis was carried out by energy dispersive x-ray (EDX) and particle induced x-ray emission (PIXE). Photoluminescence emission spectra was measured by the fluorescent spectrometer. A sedimentation technique is used to deposit the phosphor powder directly on the glass substrate using poly vinyl alcohol as a paste. A number of phosphor layers have been synthesized with the layer thickness ranging from 150 to 268 µm. Measurement results of x-ray conversion efficiency for layers were investigated using 300 kVp X-ray tube in which the maximum light output and contrast were observed for the layer with a thickness of 193 µm. Oxysulfide phosphor layer was analyzed by ion beam induced luminescence (IBIL). Emitting of green light from phosphor layer confirms its luminescence property.
Measurement of the (Gd,La)2O2S:Tb phosphor efficiency for x-ray imaging applications
Radiation Measurements, 2000
Gd,La) 2 O 2 S:Tb phosphor performance was tested under x-ray excitation for medical imaging applications with tube voltages from 70 to 180 kVp and phosphor coating weights from 20 to 240 mg/cm 2 . The emission spectrum of (Gd,La) 2 O 2 S:Tb was also measured and it was centered at 549 nm. (Gd,La) 2 O 2 S:Tb was found ecient in a wide range of x-ray tube voltages and adequately compatible with photocathodes, photodiodes, and orthochromatic ®lms currently used in x-ray medical imaging. #
UV and gamma ray induced thermoluminescence properties of cubic Gd2O3:Er3+ phosphor
Journal of Radiation Research and Applied Sciences, 2014
This paper reports the thermoluminescence properties of Er 3þ doped gadolinium oxide nanophosphor. The phosphor is prepared by high temperature solid state reaction method. The method is suitable for large scale production. Starting materials used for sample preparation were Gd 2 O 3 , Er 2 O 3 (0.5e2.5 mol%) and fixed concentration of boric acid using as a flux. The prepared samples were characterized by X-ray diffraction technique and the particle size calculated by Scherer's formula. The surface morphology of prepared phosphor is determined by scanning electron microscopic (SEM) technique. Functional group analysis was done by Fourier transform infra-red spectroscopy (FTIR) analysis. The elemental analysis of prepared sample was determined by energy dispersive X-ray analysis (EDX) and the exact particle size of prepared phosphor for the different concentration of dopant (Er 3þ) was evaluated by transmission electron microscopy (TEM) technique. The prepared phosphors for different concentration of Er 3þ were examined by thermoluminescence (TL) glow curve for UV and gamma irradiation. The UV 254 nm source was used for UV irradiation and Co 60 source was used for gamma irradiation. The samples show well resolved broad peak covered the temperature range 50e250 C and the peak temperature found at 126 C for UV irradiation and higher temperature peak at 214 C for gamma irradiation. The effect of heating rate on TL studies was presented for optimized sample. Here UV irradiated sample shows the formation of shallow trap (surface trapping) and the gamma irradiated sample shows the formation of deep trapping. The estimation of trap formation was evaluated by knowledge of trapping parameters. The trapping parameters such as activation energy, order of kinetics and frequency factor were calculated by peak shape method. Here most of the peak shows second order of kinetics. The effect of gamma and UV exposure on TL studies was also examined and it shows linear and sublinear response with dose which indicates that the sample may be useful for TL dosimetry.