A. Choubey

Spectral and trapping parameters of Eu3+ in Gd2O2S nanophosphor

This paper reports the structural, photometric, spectral and trapping parameters of Eu3+-doped gadolinium oxysulphide nanophosphor. The X-ray diffraction (XRD) data show the presence of the hexagonal phase of Gd2O2S and a crystallite size in nanometre range. Different structural parameters were calculated from XRD data. The Fourier transform infrared (FTIR) spectrum also confirms the formation of a compound. Scanning electron microscope studies reveal the morphology and crystallite size of the prepared phosphor. The band gap of the phosphor was calculated from diffuse reflectance spectra using the Kubelka–Munk function at 4.76 eV. The phosphor was illuminated with ultraviolet light and shows the characteristic red luminescence corresponding to 5D0→7FJ transitions of Eu3+. The Judd–Ofelt intensity parameters and spectral parameters were estimated from the photoluminescence data. The nanophosphor was irradiated with γ-rays in the dose range 15–50 Gy for thermoluminescence (TL) studies and a shifting of the peak towards lower temperatures was observed with increasing γ-dose. Trapping parameters were calculated from TL data using various glow curve analysis methods.

Effect of ion irradiation on the thermoluminescence properties of K2Ca2(SO4)3 phosphor

This paper presents the thermoluminescence (TL) studies of ion-irradiated potassium–calcium mixed sulfate phosphor. The sample was prepared by the solid-state diffusion method. The X-ray diffraction study of the prepared sample suggests an orthorhombic structure with an average particle size of 0.16 μ m. The samples were irradiated with 1.2 MeV argon ions at fluences varying between 1011 and 1015 ions/cm2. The argon ions penetrate to a depth of 1.93 μ m and lose their energy mainly via electronic stopping. Due to ion irradiation, a large number of defects such as oxygen vacancies, radicals and color centers are formed in the sample. TL glow curves were recorded for each of the ion fluences. A linear increase in the intensity of TL glow peaks was found with an increase in the ion dose from 72 kGy to 720 MGy. The kinetic parameters associated with the prominent glow peaks were calculated using glow curve deconvolution, different glow curve shapes and sample heating rate methods.

Study of kinetic parameters of K 2Ca 2(SO 4)3 thermoluminescence dosimeter

The dosimetry study of thermoluminescence materials is based on a good knowledge of its kinetics para-meters. A polycrystalline sample of K 2Ca 2(SO 4)3 was prepared by the solid-state diffusion method. Formation of the compound was checked by using X-ray diffraction and Fourier-transform infrared spectroscopy. Thermally stimulated luminescence (TSL) glow curves of X-ray-irradiated K 2Ca 2(SO 4)3 phosphor exhibit one glow peak at 195 °C and a shoulder at around 120 °C, indicating that two different sets of traps are being activated within the particular temperature range, each with its own value of activation energy (E) and frequency factor (s). The kinetic parameters associated with the prominent glow peak of K 2Ca 2(SO 4)3 were calculated using the isothermal luminescence decay method. The electron spin resonance study of the prepared compound exhibits the presence of and radical ions that are responsible for the observed TSL glow peaks. The release of hole/electron from trap centres at the characteristic trap site initiates the luminescence process in these materials.