Browsing by Author "Mishra, Rajat Kumar"

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    Doping impacts of La2O3 on physical, structural, optical and radiation shielding properties of (30-x)BaCO3-30TiO2-40SiO2-xLa2O3 (0 ? x ? 6) glasses for optoelectronic applications
    (Institute of Physics, 2023) Mishra, Rajat Kumar; Kumari, Savita; Shweta; Sen, Prince; Avinashi, Sarvesh Kumar; Fatima, Zaireen; Thomas, Harel; Ghosh, Manasi; Dey, Krishna Kishor; Gautam, Chandkiram
    Herein, synthesis of novel barium silicate glasses doped with La2O3 in the system (30-x)BaCO3-30TiO2-40SiO2-xLa2O3, BTSL (0 ? x ? 6) via fast melt-quenching technique was carried out. Further, to confirm the amorphous behaviour of prepared glass samples, x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were carried out. The density of all prepared glasses was determined using Archimedes� principle and found to be in an increasing manner. To investigate the doping influence of La2O3 on the glasses, few more physical properties like molar volume (Vm), polaron radius (rp), and field strength (Fs) were also studied and found to be increased due to incorporation of La2O3 into BTSL glassy system. Moreover, to explore the structural, functional, and bonding mechanism of the glasses, FTIR, Raman and 29Si-MAS-ssNMR spectroscopies were performed. Further, to investigate the numerous optical parameters, UV-visible spectroscopy was executed, and energy band gaps were found in the decreasing manner as increasing the La2O3 concentrations. Additionally, to study the optoelectronic properties, refractive indices (?) and optical dielectric constant (?) were determined and revealed the increasing behaviour and found suitable material for optoelectronic devices. Furthermore, the radiation shielding parameters, mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), etc were determined using Phy-X/PSD software and these parameters are increased owing to the doping of La2O3. Among all fabricated glasses, (30-x)BaCO3-30TiO2?40SiO2?6La2O3, BTS6L glass exhibited outstanding optical and radiation attenuation properties; can be tailored for the fabrication of optoelectronic and radiation protection devices. � 2023 IOP Publishing Ltd.
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    Enhanced physical and mechanical properties of resin added with aluminum oxyhydroxide for dental applications
    (Elsevier Ltd, 2023) Kumari, Savita; Hussain, Ajaz; Avinashi, Sarvesh Kumar; Mishra, Rajat Kumar; Rao, Jitendra; Behera, Sudhakar; Gautam, Rakesh Kumar; Gautam, Chandkiram
    Resin has limited applications however, its composites with metal oxides exhibited improved characteristics for numerous applications such as dental restoration, dentures etc. Herein, various compositions were fabricated by substituted aluminum oxyhydroxide (AlOOH) into resin via a scalable heat cure process. For phase identification and structural study, XRD and FT-IR techniques were employed. As increasing the content of AlOOH into the PZ {Poly (methyl-methacrylate)-zirconia, (PMMA-ZrO2)} matrix, the percentage of crystallinity and the crystallite size were also estimated and varied from 14.8 to 18.4 and 1.48 nm�1.82 nm respectively. Moreover, to reveal the surface morphology, optical and mechanical behaviour of fabricated nano-composites, the SEM, UV�Vis and Universal testing machine (UTM) were also performed. The direct, indirect band gap, urbach energy of the fabricated composites were noticed within the range of 5.14 � 0.005�5.19 � 0.005 eV, 5.31 � 0.005�5.35 � 0.005 eV, and 189 � 3.78�69.6 � 1.39 eV respectively. The skin depth of the nanocomposites were also studied, the cut-off energy and cutoff-wavelength are 5.66 eV and 220 nm. However, the compressive strength, flexural strength, and the lowest friction coefficient value at 1 m/s sliding speed of the best composite sample (PZA15) are 85.2 MPa, 56.7 MPa and 0.311. The highest flexural modulus (846 MPa) of the PZA15 were determined using the 3-point bending test. Further, to check the biocompatibility of these resin-based composites the MTT assay was carried out. The synthesized composite (PZA15) was found to be highly biocompatible with enhanced mechanical and tribological performances. � 2023 Elsevier Ltd and Techna Group S.r.l.
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    Physical, Structural, and Optical Properties of ZrO2 Reinforced (100-x�y)[SrTiO3]-x[2B2O3.SiO2]-y[ZrO2] Glasses
    (Springer Science and Business Media B.V., 2023) Mishra, Rajat Kumar; Shweta; Sen, Prince; Dey, Krishna Kishor; Ghosh, Manasi; Gautam, Chandkiram
    Several attempts were made to fabricate zirconia (ZrO2) reinforced strontium titanate (SrTiO3) borosilicate glasses in the system (100-x�y)[SrTiO3]-x[2B2O3.SiO2]-y[ZrO2] (38 ? x ? 39, 0 ? y ? 4 by mole %) via a rapid melt-quenching method. To check the amorphous behaviour of the prepared glasses, XRD measurements were performed. Further, density of the bulk transparent glasses was evaluated by liquid-displacement method (Archimedes� principle) and found to be in the range of 2.6068�3.0720 gcm?3. To study the effect of ZrO2 doping on the fabricated glasses, various physical parameters such as oxygen molar volume (Omv), molar volume (Vm), oxygen packing density (OPD), ion-concentrations (N), etc. were determined. Further, to investigate the molecular structure, and bonding information, FTIR spectroscopy was performed. Additionally, to determine the various optical properties, the UV�visible spectroscopy was also performed, and with the help of Davis-Mott plots, increasing optical band gap energies were obtained in the range of 4.29�4.78�eV. Besides these parameters, an optical dielectric constant (?), and average refractive index (?) were determined which lies within the increasing range of 120.0374�207.3341 and 1.9269�2.0690 respectively. Moreover, to elaborate the structure of the fabricated glasses, 29Si and 11B MAS SSNMR spectra were recorded which shows the formation of silicate networks which became highly polymerized with increasing concentrations of ZrO2. � 2023, The Author(s), under exclusive licence to Springer Nature B.V.
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    Synthesis, physical, optical and structural properties of SrTiO3 borosilicate glasses with addition of CrO3
    (Springer, 2023) Madheshiya, Abhishek; Singh, Anod Kumar; Shweta; Mishra, Rajat Kumar; Dey, Krishna Kishor; Ghosh, Manasi; Srivastava, Kamal K; Garg, Prerna; Gautam, Chandkiram
    Herein, we reported physical, optical and NMR characteristics of SrTiO3-based borosilicate glasses-doped chromium trioxide, CrO3 (1�7 mol%). Five glass samples (GS) were fabricated from the glassy system 60[Sr�TiO3]�40[2SiO2�B2O3] via a rapid melt-quench technique. X-ray diffraction analysis revealed the unstructured behaviour of the glasses. Numerous physical parameters were calculated and explained in detail. Urbach energy (EU) and skin depth (?) were studied to approve the disordered structure of glasses. Recorded infrared spectra of glasses were utilized to clarify the stretching mode of vibrations between the atoms, which correlated with their structural features and compositional variations. The energy bandgap (Eg) was estimated by employing a Davis and Mott relationship that comprises an absorption coefficient, ?, as well as photon energy, h?. Further, nuclear magnetic resonance (solid-state) spectra of the glasses were recorded and their analysis showed that the silicate and borate networks became highly polymerized with decreasing concentration of SrTiO3. � 2023, Indian Academy of Sciences.