babita tiwari - Academia.edu (original) (raw)
Papers by babita tiwari
Radiation Measurements, 2022
Radiation Measurements, 2016
h i g h l i g h t s Li 2 B 4 O 7 :Ag single crystals are grown by the Czochralski technique. Li 2... more h i g h l i g h t s Li 2 B 4 O 7 :Ag single crystals are grown by the Czochralski technique. Li 2 B 4 O 7 :Ag single crystals are investigated using TSL, OSL techniques. These crystals are found promising for OSL dosimetry.
ABSTRACT High quality lithium tetraborate; Li2B4O7 (LTB) single crystals with varying concentrati... more ABSTRACT High quality lithium tetraborate; Li2B4O7 (LTB) single crystals with varying concentrations of Ag have been grown using the Czochralski technique. Optimized growth parameters enabled us to grow crystals that were transparent, colorless, crack-free, and core-free. The grown LTB:Ag crystals were characterized using UV-VIS-NIR transmission, photoluminescence (PL) and thermoluminescence (TL) measurements. The transmission of about 85 % in the range from 200 nm to 1100 nm revealed a good optical quality of the grown crystals. The TL glow peak of LTB:Ag single crystals at 160°C with an emission at 270 nm is found useful for the dosimetric applications. The dose response is found to be linear in the range from 100 mGy to 50 Gy.
Journal of Materials Science: Materials in Electronics
Physica B: Condensed Matter, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Materials Research Express, 2018
Lead free ceramics Ba1−x Ln2x/3Zr0.3Ti0.7O3 (Ln = La, Nd, Sm, Eu and Sc), x = 0.02–0.10 are inves... more Lead free ceramics Ba1−x Ln2x/3Zr0.3Ti0.7O3 (Ln = La, Nd, Sm, Eu and Sc), x = 0.02–0.10 are investigated for electrostrictive effect and energy storage properties in the proximity of relaxor-paraelectric phase boundary. Relaxor phase evidence from slim hysteresis loop and low remnant polarization are the key parameters responsible for improve the electrostrictive effect and energy storage properties simultaneously. With increase in rare earth content negative strain disappeared and almost hysteresis free strain is achieved. Strain-hysteresis profile in term of S–E, S–E 2 and S–P 2 is used to analyze the electrostrictive behavior of these ceramics. An average strain (S%) ~ 0.03%, is accomplished at initial concentrations of x = 0.02–0.04 and electrostrictive coefficients (Q 11, and M 11) as well as the energy storage density is improved by a factor of 1.2 and 2.6 respectively when compare with pure (x = 0.0) ceramic. Above x ≥ 0.06, all compositions show a stable behavior which suggested the possibilities of these relaxor ceramics towards high precision actuators and energy storage application.
Journal of Alloys and Compounds, 2018
A solid solution of lead-free piezoelectric ceramic (1-x)Bi 0.50 (Na 0.80 K 0.20) 0.50 TiO 3-xBa ... more A solid solution of lead-free piezoelectric ceramic (1-x)Bi 0.50 (Na 0.80 K 0.20) 0.50 TiO 3-xBa 0.90 Ca 0.10 Ti 0.90 Zr 0.10 O 3 (with x=0.00, 0.02, 0.04, 0.06, 0.08) was synthesized by conventional solid-state reaction route. The effect of addition of BCZT on BNKT was investigated on structural, microstructural, dielectric, ferroelectric, piezoelectric and high-density energy storage properties experimentally. Modified Curie Weiss law and Vogel-Fulcher law were employed to study the diffusivity and activation energy. The dielectric dispersion with frequency reveals the relaxor behavior for all compositions. The value of T v (calculated from Vogel-Fulcher relation) decreases while the corresponding value of E a increases with the BCZT composition. The unipolar curve shows the increased strain of 0.15% and corresponding ݀ ଷଷ * (S max /E max =311 pm/V) for x = 0.02 composition among all studied compositions. Furthermore, compositions x = 0.02 and x = 0.04 shows the improved energy storage efficiency ∼50% with respect to pure BNKT.
barc.ernet.in
Device-grade single crystals of technologically important materials for use as scintillators in n... more Device-grade single crystals of technologically important materials for use as scintillators in nuclear radiation detection, lasers and optical devices are grown in Crystal Technology Section of the Technical Physics Division. The expertise has been developed to establish crystal growth ...
A b s t r a c t Clear bubble-free phosphate glasses, having composition 40Na 2 O-10Al 2 O 3 -xTiO... more A b s t r a c t Clear bubble-free phosphate glasses, having composition 40Na 2 O-10Al 2 O 3 -xTiO 2 -(50-x)P 2 O 5 , (x = 0-20 mol %), were prepared by conventional melt quench method. Density, molar volume, glass transition temperature (Tg), MicroHardness (MH), and Thermal Expansion Coefficient (TEC) were measured as a function of TiO 2 content. Structural investigation was done using Raman and FTIR spectroscopy. Substitution of TiO 2 for P 2 O 5 up to 10 mol %, in the ternary 40Na 2 O-10Al 2 O 3 -50P 2 O 5 glass increases the density, Tg and MH. Above the 10 mol % TiO 2 content, all these properties show a reverse trend. Spectroscopic investigations reveal the depolymerization of the phosphate glass network by systematic conversion of Q 2 structural units into Q 1 and finally into Q 0 structural units. Even though Q 2 to Q 1 conversion is taking place due to breaking of P-O-P linkages, formation of P-O-Ti and P-O-Al linkages provide cross linking between short P-structural units, ...
Single crystals of Ce doped Li 6 Y(BO 3 ) 3 have potential applications to be used as a scintilla... more Single crystals of Ce doped Li 6 Y(BO 3 ) 3 have potential applications to be used as a scintillator to detect thermal neutrons. These single crystals having an optimum Ce concentration been successfully grown using the Czochralski technique. The crystals have been characterized for optical and scintillation properties. A portable detectors set-up that works from a USB port of a laptop has been developed to detect thermal neutrons. The detection efficiencies in excess of 80% have been achieved even for thin slices of the crystal (1 mm thick) mounted on a photo-multiplier tube (PMT).
Crack-free single crystals of Ce doped Gd 3 Ga 3 Al 2 O 12 have been grown in Ar ambient using th... more Crack-free single crystals of Ce doped Gd 3 Ga 3 Al 2 O 12 have been grown in Ar ambient using the Czochralski technique. These crystals were investigated with a view to improve the scintillation properties by a suitable post-growth annealing treatment. The Gd 3 Ga 3 Al 2 O 12 :Ce crystal scintillators having improved performances were coupled to a PMT to develop a portable gamma-ray spectrometer that could be powered from a USB port of a laptop. The scintillator crystal was also coupled to photodiodes and pulse height characteristics were measured for gamma-rays and charged particles in order to explore the possibility of fabricating detectors with a compact geometry.
Ce doped YAlO3 (YAP:Ce) is one of the excellent scintillators with many advantageous properties l... more Ce doped YAlO3 (YAP:Ce) is one of the excellent scintillators with many advantageous properties like fast decay (~30 ns), good light yield (20-25k photons/MeV), moderate density (5.3 g/cc) and proportional scintillation response. It is useful in various radiation detection applications like imaging, gamma-ray detectors, timing applications and many others [1]. Single crystals of YAP are generally grown by the Czochralski technique. The scintillation properties of the materials are highly dependent on the crystal growth parameters [2]. In this paper we are presenting the effect of variation in stoichiometry of the melt on the scintillation properties of YAP:Ce.
Indian Journal of Dryland Agricultural Research and Development, 2020
International Journal of Current Microbiology and Applied Sciences, 2018
AIP Conference Proceedings, 2012
ABSTRACT High optical quality Li2B4O7 (LTB) single crystals and glassy phases of pure, doped (Cu,... more ABSTRACT High optical quality Li2B4O7 (LTB) single crystals and glassy phases of pure, doped (Cu, Ag) and co-doped with Cu+Ag have been grown by Czochralski crystal pulling and melt quenching techniques respectively. They were characterized through photoluminescence (PL), thermoluminescence (TL), and UV-VIS-NIR transmission measurements. The PL of glass phase shows light yield comparable to that of single crystal. 80-85 % optical transmission in the range 350-800 nm revealed good optical quality of the glasses which is comparable to the single crystals though the glasses have higher cut off wavelength (lower energy). TL glow peaks of Cu doped LTB single crystal at 200 °C and for Cu+Ag co-doped LTB single crystals at around 170°C and 240°C are useful for the dosimetry applications and found to be linear in the range from 1mGy to 1kGy. However, in glasses no TL was observed in spite of a good PL yield.
Journal of Luminescence, 2015
Single crystals of Li 2 B 4 O 7 (LTB) with varying Ag content were grown using the Czochralski te... more Single crystals of Li 2 B 4 O 7 (LTB) with varying Ag content were grown using the Czochralski technique and studied for their optical absorption, photo-luminescence (PL) and thermally stimulated luminescence (TSL) properties. The optimum Ag concentration in the LTB was found to be about 500 ppm for the best TSL properties. A TSL readout setup has been described that uses a solar blind photo-multiplier tube (PMT) to match the emission from Ag which is in the UV region (peak at 270 nm). This has significantly improved the performance of the TSL setup by lowering dark counts and enhancing the signal due to a better matching between the emission from Ag ions and PMT response. In addition, the use of the solar blind PMT also minimized the thermal noise generated from heating of sample in the TSL setup. Radiation doses lower than 5 μGy could be measured using this setup with small LTB:Ag crystal samples (100 mg). The lower detection limit has been estimated to be 500 nGy.
Advanced Materials Research, 2012
Glasses in the SrO-ZnO-B2O3-SiO2 (SZBS) system with different additives like V2O5, Cr2O3, TiO2, a... more Glasses in the SrO-ZnO-B2O3-SiO2 (SZBS) system with different additives like V2O5, Cr2O3, TiO2, and Al2O3 have been prepared by melt-quench method. Glasses were subjected to controlled heat treatment for conversion into glass-ceramics. Investigated glasses and glass-ceramics have thermal expansion coefficients (TEC) in the range of 95-120 x 10-7/oC (30-600 oC) which closely match with TEC of other SOFC components. XRD indicates the crystallization of Sr2ZnSi2O7 solid-solution phase in glasses upon heat treatment. Structural studies revealed that mainly Q1 and Q2 silicate structural units are present in the glass network and B2O3 enters in the network as triangular borate (BO3) structural units. Only small fraction of B2O3 enters as tetragonal borate (BO4) structural units at higher concentration of B2O3. Glass network depolymerizes with the addition of additives and concentration of Q1 units increases at the expense of Q2 units. Small addition of V2O5 in SZBS glass is beneficial for...
Radiation Measurements, 2022
Radiation Measurements, 2016
h i g h l i g h t s Li 2 B 4 O 7 :Ag single crystals are grown by the Czochralski technique. Li 2... more h i g h l i g h t s Li 2 B 4 O 7 :Ag single crystals are grown by the Czochralski technique. Li 2 B 4 O 7 :Ag single crystals are investigated using TSL, OSL techniques. These crystals are found promising for OSL dosimetry.
ABSTRACT High quality lithium tetraborate; Li2B4O7 (LTB) single crystals with varying concentrati... more ABSTRACT High quality lithium tetraborate; Li2B4O7 (LTB) single crystals with varying concentrations of Ag have been grown using the Czochralski technique. Optimized growth parameters enabled us to grow crystals that were transparent, colorless, crack-free, and core-free. The grown LTB:Ag crystals were characterized using UV-VIS-NIR transmission, photoluminescence (PL) and thermoluminescence (TL) measurements. The transmission of about 85 % in the range from 200 nm to 1100 nm revealed a good optical quality of the grown crystals. The TL glow peak of LTB:Ag single crystals at 160°C with an emission at 270 nm is found useful for the dosimetric applications. The dose response is found to be linear in the range from 100 mGy to 50 Gy.
Journal of Materials Science: Materials in Electronics
Physica B: Condensed Matter, 2019
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Materials Research Express, 2018
Lead free ceramics Ba1−x Ln2x/3Zr0.3Ti0.7O3 (Ln = La, Nd, Sm, Eu and Sc), x = 0.02–0.10 are inves... more Lead free ceramics Ba1−x Ln2x/3Zr0.3Ti0.7O3 (Ln = La, Nd, Sm, Eu and Sc), x = 0.02–0.10 are investigated for electrostrictive effect and energy storage properties in the proximity of relaxor-paraelectric phase boundary. Relaxor phase evidence from slim hysteresis loop and low remnant polarization are the key parameters responsible for improve the electrostrictive effect and energy storage properties simultaneously. With increase in rare earth content negative strain disappeared and almost hysteresis free strain is achieved. Strain-hysteresis profile in term of S–E, S–E 2 and S–P 2 is used to analyze the electrostrictive behavior of these ceramics. An average strain (S%) ~ 0.03%, is accomplished at initial concentrations of x = 0.02–0.04 and electrostrictive coefficients (Q 11, and M 11) as well as the energy storage density is improved by a factor of 1.2 and 2.6 respectively when compare with pure (x = 0.0) ceramic. Above x ≥ 0.06, all compositions show a stable behavior which suggested the possibilities of these relaxor ceramics towards high precision actuators and energy storage application.
Journal of Alloys and Compounds, 2018
A solid solution of lead-free piezoelectric ceramic (1-x)Bi 0.50 (Na 0.80 K 0.20) 0.50 TiO 3-xBa ... more A solid solution of lead-free piezoelectric ceramic (1-x)Bi 0.50 (Na 0.80 K 0.20) 0.50 TiO 3-xBa 0.90 Ca 0.10 Ti 0.90 Zr 0.10 O 3 (with x=0.00, 0.02, 0.04, 0.06, 0.08) was synthesized by conventional solid-state reaction route. The effect of addition of BCZT on BNKT was investigated on structural, microstructural, dielectric, ferroelectric, piezoelectric and high-density energy storage properties experimentally. Modified Curie Weiss law and Vogel-Fulcher law were employed to study the diffusivity and activation energy. The dielectric dispersion with frequency reveals the relaxor behavior for all compositions. The value of T v (calculated from Vogel-Fulcher relation) decreases while the corresponding value of E a increases with the BCZT composition. The unipolar curve shows the increased strain of 0.15% and corresponding ݀ ଷଷ * (S max /E max =311 pm/V) for x = 0.02 composition among all studied compositions. Furthermore, compositions x = 0.02 and x = 0.04 shows the improved energy storage efficiency ∼50% with respect to pure BNKT.
barc.ernet.in
Device-grade single crystals of technologically important materials for use as scintillators in n... more Device-grade single crystals of technologically important materials for use as scintillators in nuclear radiation detection, lasers and optical devices are grown in Crystal Technology Section of the Technical Physics Division. The expertise has been developed to establish crystal growth ...
A b s t r a c t Clear bubble-free phosphate glasses, having composition 40Na 2 O-10Al 2 O 3 -xTiO... more A b s t r a c t Clear bubble-free phosphate glasses, having composition 40Na 2 O-10Al 2 O 3 -xTiO 2 -(50-x)P 2 O 5 , (x = 0-20 mol %), were prepared by conventional melt quench method. Density, molar volume, glass transition temperature (Tg), MicroHardness (MH), and Thermal Expansion Coefficient (TEC) were measured as a function of TiO 2 content. Structural investigation was done using Raman and FTIR spectroscopy. Substitution of TiO 2 for P 2 O 5 up to 10 mol %, in the ternary 40Na 2 O-10Al 2 O 3 -50P 2 O 5 glass increases the density, Tg and MH. Above the 10 mol % TiO 2 content, all these properties show a reverse trend. Spectroscopic investigations reveal the depolymerization of the phosphate glass network by systematic conversion of Q 2 structural units into Q 1 and finally into Q 0 structural units. Even though Q 2 to Q 1 conversion is taking place due to breaking of P-O-P linkages, formation of P-O-Ti and P-O-Al linkages provide cross linking between short P-structural units, ...
Single crystals of Ce doped Li 6 Y(BO 3 ) 3 have potential applications to be used as a scintilla... more Single crystals of Ce doped Li 6 Y(BO 3 ) 3 have potential applications to be used as a scintillator to detect thermal neutrons. These single crystals having an optimum Ce concentration been successfully grown using the Czochralski technique. The crystals have been characterized for optical and scintillation properties. A portable detectors set-up that works from a USB port of a laptop has been developed to detect thermal neutrons. The detection efficiencies in excess of 80% have been achieved even for thin slices of the crystal (1 mm thick) mounted on a photo-multiplier tube (PMT).
Crack-free single crystals of Ce doped Gd 3 Ga 3 Al 2 O 12 have been grown in Ar ambient using th... more Crack-free single crystals of Ce doped Gd 3 Ga 3 Al 2 O 12 have been grown in Ar ambient using the Czochralski technique. These crystals were investigated with a view to improve the scintillation properties by a suitable post-growth annealing treatment. The Gd 3 Ga 3 Al 2 O 12 :Ce crystal scintillators having improved performances were coupled to a PMT to develop a portable gamma-ray spectrometer that could be powered from a USB port of a laptop. The scintillator crystal was also coupled to photodiodes and pulse height characteristics were measured for gamma-rays and charged particles in order to explore the possibility of fabricating detectors with a compact geometry.
Ce doped YAlO3 (YAP:Ce) is one of the excellent scintillators with many advantageous properties l... more Ce doped YAlO3 (YAP:Ce) is one of the excellent scintillators with many advantageous properties like fast decay (~30 ns), good light yield (20-25k photons/MeV), moderate density (5.3 g/cc) and proportional scintillation response. It is useful in various radiation detection applications like imaging, gamma-ray detectors, timing applications and many others [1]. Single crystals of YAP are generally grown by the Czochralski technique. The scintillation properties of the materials are highly dependent on the crystal growth parameters [2]. In this paper we are presenting the effect of variation in stoichiometry of the melt on the scintillation properties of YAP:Ce.
Indian Journal of Dryland Agricultural Research and Development, 2020
International Journal of Current Microbiology and Applied Sciences, 2018
AIP Conference Proceedings, 2012
ABSTRACT High optical quality Li2B4O7 (LTB) single crystals and glassy phases of pure, doped (Cu,... more ABSTRACT High optical quality Li2B4O7 (LTB) single crystals and glassy phases of pure, doped (Cu, Ag) and co-doped with Cu+Ag have been grown by Czochralski crystal pulling and melt quenching techniques respectively. They were characterized through photoluminescence (PL), thermoluminescence (TL), and UV-VIS-NIR transmission measurements. The PL of glass phase shows light yield comparable to that of single crystal. 80-85 % optical transmission in the range 350-800 nm revealed good optical quality of the glasses which is comparable to the single crystals though the glasses have higher cut off wavelength (lower energy). TL glow peaks of Cu doped LTB single crystal at 200 °C and for Cu+Ag co-doped LTB single crystals at around 170°C and 240°C are useful for the dosimetry applications and found to be linear in the range from 1mGy to 1kGy. However, in glasses no TL was observed in spite of a good PL yield.
Journal of Luminescence, 2015
Single crystals of Li 2 B 4 O 7 (LTB) with varying Ag content were grown using the Czochralski te... more Single crystals of Li 2 B 4 O 7 (LTB) with varying Ag content were grown using the Czochralski technique and studied for their optical absorption, photo-luminescence (PL) and thermally stimulated luminescence (TSL) properties. The optimum Ag concentration in the LTB was found to be about 500 ppm for the best TSL properties. A TSL readout setup has been described that uses a solar blind photo-multiplier tube (PMT) to match the emission from Ag which is in the UV region (peak at 270 nm). This has significantly improved the performance of the TSL setup by lowering dark counts and enhancing the signal due to a better matching between the emission from Ag ions and PMT response. In addition, the use of the solar blind PMT also minimized the thermal noise generated from heating of sample in the TSL setup. Radiation doses lower than 5 μGy could be measured using this setup with small LTB:Ag crystal samples (100 mg). The lower detection limit has been estimated to be 500 nGy.
Advanced Materials Research, 2012
Glasses in the SrO-ZnO-B2O3-SiO2 (SZBS) system with different additives like V2O5, Cr2O3, TiO2, a... more Glasses in the SrO-ZnO-B2O3-SiO2 (SZBS) system with different additives like V2O5, Cr2O3, TiO2, and Al2O3 have been prepared by melt-quench method. Glasses were subjected to controlled heat treatment for conversion into glass-ceramics. Investigated glasses and glass-ceramics have thermal expansion coefficients (TEC) in the range of 95-120 x 10-7/oC (30-600 oC) which closely match with TEC of other SOFC components. XRD indicates the crystallization of Sr2ZnSi2O7 solid-solution phase in glasses upon heat treatment. Structural studies revealed that mainly Q1 and Q2 silicate structural units are present in the glass network and B2O3 enters in the network as triangular borate (BO3) structural units. Only small fraction of B2O3 enters as tetragonal borate (BO4) structural units at higher concentration of B2O3. Glass network depolymerizes with the addition of additives and concentration of Q1 units increases at the expense of Q2 units. Small addition of V2O5 in SZBS glass is beneficial for...