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A Thorough Investigation of Electronic, Optical, Mechanical, and Thermodynamic Properties of Stable Glasslike Sodium Germanate under Compressive Hydrostatic Pressure: Ab Initio Study

2023-01-01T00:00:00Z

Title: A Thorough Investigation of Electronic, Optical, Mechanical, and Thermodynamic Properties of Stable Glasslike Sodium Germanate under Compressive Hydrostatic Pressure: Ab Initio Study Authors: Devi, Rangeela Y Abstract: In this paper, we have tried to elucidate the variation of structural, electronic, and thermodynamic properties of glasslike Na2GeO3 under compressive isotropic pressure within a framework of density functional theory (DFT). The result shows stable structural (orthorhombic → tetragonal) and electronic (indirect → direct) phase transitions at P ∼ 20 GPa. The electronic band gap transition plays a key role in the enhancement of optical properties. The results of the thermodynamic properties have shown that Na2GeO3 follows Debye’s lowtemperature specific heat law and the classical thermodynamic of the Dulong−Petit law at high temperature. The pressure sensitivity of the electronic properties led us to compute the piezoelectric tensor (both in relaxed and clamped ions). We have observed significant electric responses in the form of a piezoelectric coefficient under applied pressure. This property suggested that Na2GeO3 could be a potential material for energy harvest in future energy-efficient devices. As expected, Na2GeO3 becomes harder and harder under compressive pressure up to the phase transition pressure (∼20 GPa) which can be read from Pugh’s ratio (kH) > 1.75, however, at pressures above 20 GPa kH < 1.75, which may be due to the formation of fractures at high pressure

The dependence of peak intensity of a thermoluminescence (TL) peak under the one- trap-onerecombination centre (OTOR) model on the initial occupancy of electrons/ holes is considered for different heating schemes. It is observed that for linear heating scheme, ImTm 2(Im=peak intensity, Tm =peak temperature) is proportional to initial concentration of trapped electrons (n0) i.e., to radiation dose. For hyperbolic heating scheme, Im is proportional to n0. These results will be of significance in TL dosimetry and dating.

2015-04-15T00:00:00Z

Title: The dependence of peak intensity of a thermoluminescence (TL) peak under the one- trap-onerecombination centre (OTOR) model on the initial occupancy of electrons/ holes is considered for different heating schemes. It is observed that for linear heating scheme, ImTm 2(Im=peak intensity, Tm =peak temperature) is proportional to initial concentration of trapped electrons (n0) i.e., to radiation dose. For hyperbolic heating scheme, Im is proportional to n0. These results will be of significance in TL dosimetry and dating. Authors: Devi, Rangeela Y Abstract: The dependence of peak intensity of a thermoluminescence (TL) peak under the one- trap-onerecombination centre (OTOR) model on the initial occupancy of electrons/ holes is considered for different heating schemes. It is observed that for linear heating scheme, ImTm 2(Im=peak intensity, Tm =peak temperature) is proportional to initial concentration of trapped electrons (n0) i.e., to radiation dose. For hyperbolic heating scheme, Im is proportional to n0. These results will be of significance in TL dosimetry and dating.

On the initial occupancy dependence of thermoluminescence under the OTOR model with different heating profiles

2016-05-01T00:00:00Z

Title: On the initial occupancy dependence of thermoluminescence under the OTOR model with different heating profiles Authors: Devi, Rangeela Y Abstract: The dependence of peak intensity of a thermoluminescence (TL) peak under the one- trap-onerecombination centre (OTOR) model on the initial occupancy of electrons/ holes is considered for different heating schemes. It is observed that for linear heating scheme, ImTm 2(Im=peak intensity, Tm =peak temperature) is proportional to initial concentration of trapped electrons (n0) i.e., to radiation dose. For hyperbolic heating scheme, Im is proportional to n0. These results will be of significance in TL dosimetry and dating.

Effects of annealing temperature on fading characteristics of BaSO4: Dy, Mn phosphor

2013-01-01T00:00:00Z

Title: Effects of annealing temperature on fading characteristics of BaSO4: Dy, Mn phosphor Authors: Devi, Rangeela Y Abstract: This study examines the effect of annealing on TL glow curve structure. For this, studies of Ba0.92SO4:Dy0.04Mn0.04 phosphor subjected to pre-irradiation high temperature treatment was carried out. Analysis of the TL glow curve indicated that there was drastic change in the glow curve structure of the phosphor annealed at high temperature. The TL peak at 401 K disappears, whereas the intensity of the other peaks increases with increase in the annealing temperature in the temperature range 873-1173 K. To test post-irradiation fading, the annealed samples were irradiated with gamma ray and stored at room temperature for 7- 10 days and TL glow curves were recorded everyday over these days