Papers by Ashwitha D'Souza
Indian Journal of Physics, Jan 4, 2023
In the present study, Eu 3?-doped zinc fluoro-telluroborate transparent glasses were prepared by ... more In the present study, Eu 3?-doped zinc fluoro-telluroborate transparent glasses were prepared by the conventional melt-quench technique. Their density and refractive index values were measured, and using these values, different physical parameters (number density, oxygen packing density, no. of bonds/vol, etc.) were calculated and analysed. The XRD pattern displayed a disordered atomic arrangement in the glass network. The EDS spectra proved the purity of the samples exhibiting only those elements used during the synthesis. The good solubility of Eu 3? ions in zinc fluorotelluroborate glasses was analysed through fine absorption peaks in the UV-Vis-NIR range. The absorption intensities increased in all samples up to 3.0 mol% of Eu 3?-doping concentration. The stabilities of the samples, such as DT * (144-156)°C and H r * 2.33-4.00, calculated using characteristic temperatures (T g , T x , T c , T m) from DSC studies exhibited their promising candidature in a high-temperature environment. The Eu7 (Eu 3? with 3.0 mol%) glass confirmed better attenuation properties (LAC, Z eff , HVL, MFP) compared to other composition (0-2.5 mol%) glasses.
Materials Chemistry and Physics
Radiation Physics and Chemistry
Journal of Materials Research and Technology, 2022
Materials Research, 2021
This article contains detailed evaluation of thermal, mechanical, radiation shielding and thermol... more This article contains detailed evaluation of thermal, mechanical, radiation shielding and thermoluminescence (TL) properties of heavy metal oxide (HMO) borosilicate glasses having composition xBi 2 O 3-(60-x) B 2 O 3-20SiO 2-12ZnO-8BaO (with x= 0, 2, 4, 6, 8, 10 and 12 mol%). Gamma shielding capacity of these glasses was examined in terms of mass attenuation coefficient (MAC) values, exposure and energy absorption build-up factor (EBF/EABF). The experimental MAC values were found to agree well with the theoretical results obtained from Photon Shielding and Dosimetry (PSD/Phy-X) software. Geometric Progression fitting method was used for the calculation of build-up factors in the photon energy region of 0.015-15 MeV with the help of five parameters (a, b, c, d and X k). The pattern followed by build-up factors with the gamma energy and their variation for different penetration depths up to 40 mfp was observed and analysed. High values of equivalent atomic number and build up factors for high bismuth sample (12 mol%) gave evidence for its improved radiation shielding capacity. Furthermore, thermoluminescence study was done to assess the suitability of the synthesized glasses as a radiation dosimeter in the gamma dose range of 0.25-30 kGy. Here, 5 kGy irradiation exhibited major quenching in TL signal on adding bismuth to the glass network. TL performance of ZBiB-8 was noteworthy with charges trapped in high temperature trap centres with longer lifetime. TL dose response curve of ZBiB-8 showed good linearity in the dose range of 0.25-5 kGy. Fading analysis was done for this sample to find the loss in TL intensity in the course of one month. Heating the ZBiB-8 sample to 323 K (50 0 C) for 15 min was found to be a proper annealing condition for re-using it as a thermoluminescence dosimeter (TLD).
Journal of Non-Crystalline Solids, 2021
Abstract A series of Tm3+ doped lithium sodium barium borate glasses with following matrix compos... more Abstract A series of Tm3+ doped lithium sodium barium borate glasses with following matrix compositions (50-x) B2O3-10BaO-10MgO-10Li2O-10Na2O-10LiF-xTm2O3 (x=0.25, 0.5, 1.0 and 1.5 mol %) were prepared by melt-quenching technique. The structural, dielectric, optical and luminescence properties of the glasses were studied. FTIR study shows the presence of various vibrational bands and the number of bridging (N4) and non-bridging (N3) oxygens were calculated from the deconvoluted FTIR spectra. The frequency and temperature dependent dielectric properties were analyzed in the frequency range 1Hz-1MHz and the temperature ranges 50 - 400 °C. The UV-Visible-NIR spectrum of the glasses showed the presence of five transition peaks emerging from the ground state (3H6) of Tm3+ ions. Bonding parameter showed the ionic nature exists between Tm3+ ions and its neighbouring ligands. Judd-Ofelt parameters were calculated following the same trend as Ω2 >Ω6> Ω4 for all the prepared glasses. The emission spectra of the glasses were recorded in the visible region and exhibited a strong blue emission at 454 nm from the level 1D2 → 3F4. Also, the prepared glasses have high experimental branching ratio value (~0.9) which suggests that the prepared glasses can be used for blue laser application. Commission Internationale de I'Eclairage (CIE) coordinates and color correlated temperature (CCT) values (~1500K) supported the application of the glasses for cool blue solid-state lighting.
Radiation Physics and Chemistry
Journal of Non-Crystalline Solids
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Papers by Ashwitha D'Souza