Browsing by Author "Saswata Chakraborty"

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Enhancing glass-forming ability and mechanical properties of barium-calcium-aluminate glasses through ZnO inclusion
(Elsevier B.V., 2024) Saswata Chakraborty; Sudheer Ganisetti; Sathravada Balaji; Sultan Khan; Sushanta K. Mohapatra; Pritha Patra; Prince Sen; Manasi Ghosh; Krishna Kishor Dey; N.M. Anoop Krishnan; Kaushik Biswas; Amarnath R Allu; Kalyandurg Annapurna
Calcium aluminate (CA) glasses have garnered attention in the field of infrared photonics due to their low phonon energy. Nonetheless, the poor glass-forming ability (GFA) and strong crystallization tendency have hindered their utilization in various technological applications. Therefore, we demonstrate here that the substitution of ZnO for CaO enhances the GFA of 29Al2O3–(66X)CaO–5BaO–(X)ZnO (X = 0,7,10,15,20,25) glasses and improves their mechanical properties. The structural characterization using Raman, 27Al MAS-NMR spectroscopy and MD simulations reveal that, Zn2+ ions adopt tetrahedral coordination and contribute as network formers along with Al3+ ions. Notably, MD simulations indicate a preference of ZnO4 units for the CaO6 sites to convert non-bridging oxygens to bridging oxygens. The decrease in glass transition temperature and the increase in elastic modulus is noticed which correlated with the structural changes in the studied glasses. These findings provide valuable insights into the design and development of stable multicomponent CA glasses for photonic applications. © 2024
Role of Sodium-Ion Dynamics and Characteristic Length Scales in Ion Conductivity in Aluminophosphate Glasses Containing Na2SO4
(American Chemical Society, 2022) Indrajeet Mandal; Saswata Chakraborty; K. Jayanthi; Manasi Ghosh; Krishna K. Dey; K. Annapurna; Jayanta Mukhopadhyay; Abhijit Das Sharma; Amarnath R. Allu
Achieving high ion conductivity in glass-based Na-ion conducting materials for their applications as solid electrolytes in batteries is still challenging owing to the vague knowledge on the factors governing Na-ion dynamics. In the present study, an attempt has been made to identify the factors affecting the sodium-ion dynamics through structure and conductivity property correlation for the 37.5Na2O-37.5P2O5-15Al2O3-10NaF (FS-0; mol %) glass system with varied concentrations of Na2SO431P, 27Al, and 23Na MAS NMR (magic-angle spinning nuclear magnetic resonance) and Raman spectroscopy are employed to assess the structural modifications, and impedance spectroscopy is used to measure the variations in ionic conductivity on the addition of Na2SO4 in the FS-0 glass. Raman spectra and MAS NMR analysis indicate that the quantity of P-O-Na bonds and sulfate (SO42-) units surrounded by sodium increase with increasing Na2SO4 concentration. Impedance analysis reveals that the conductivity of FS-0 glass enhances by 1 order with the addition of 6 mol % Na2SO4. We identify from the ac-conductivity spectral analysis that the concentration of charge carriers and the critical hopping length of mobile cations increase with the addition of 6 mol % Na2SO4. Overall, we reveal that the structural modifications, Na-ion concentration, and the shallower potential well that is created for sodium due to its interaction with the nearest neighboring cations affect the Na-ion dynamics. The information obtained from the present study certainly helps to optimize the chemical composition of glasses demonstrating high ionic conductivity. © 2022 American Chemical Society
Structure and Conductivity Correlation in NASICON Based Na3Al2P3O12 Glass: Effect of Na2SO4
(Frontiers Media S.A., 2022) Indrajeet Mandal; Saswata Chakraborty; Manasi Ghosh; Krishna K. Dey; K. Annapurna; Amarnath R. Allu
Identifying the factors influencing the movement of sodium cations (Na+) in glasses accelerates the possible options of glass-based solid electrolyte materials for their applications as a promising electrolyte material in sodium-ion batteries. Nevertheless, due to the poor correlation between the structure and conductivity in glass materials, identifying the factors governing the conductivity still exists as a challenging task. Herein, we have investigated the DC-conductivity variations by correlating the structure and conductivity in sodium superionic conductor (NASICON) based Na3Al2P3O12 (NAP) glass (mol%: 37.5 P2O5—25.0 Al2O3—37.5 Na2O) due to the successive substitution of Na2SO4 for Al2O3. Structural variations have been identified using the Raman and magic-angle spinning nuclear magnetic resonance (MAS-NMR) (for 31P, 23Na, and 27Al nuclei) and conductivity measurements have been done using the impedance spectroscopy. From the ac-conductivity spectra, the correlations between mean square displacement (MSD) and dc-conductivity and between the Na+ concentration and dc-conductivity have also been evaluated. Raman spectra reveal that the increase in the Na2SO4 concentration increases the number of isolated SO42− sulfate groups that are charge compensated by the Na+ cations in the NAP glass. MAS-NMR spectra reveal that the increase in Na2SO4 concentration increases the concentration of non-bridging oxygens and further neither S-O-P nor S-O-Al bonds are formed. Impedance spectroscopy reveals that, at 373 K, the DC conductivity of the NAP glass increases with increasing the Na2SO4 up to 7.5 mol% and then decreases with the further increase. In the present study, we have shown that the mobility of sodium cations played a significant role in enhancing the ionic-conductivity. Further, we have shown that inter-ionic Coulombic interactions and the structural modification with the formation of SO42− units significantly influence the critical hopping length < R2 (tp)> of the sodium cations and consequently the mobility and the ionic conductivity. The present study clearly indicates that, based on the compositions, glass materials can also be treated as strong-electrolyte materials. Copyright © 2022 Mandal, Chakraborty, Ghosh, Dey, Annapurna and Allu.
Structure-Property Correlation in Ba/Sr-Ca-Mg-Zn-Si-Al-O Glass: Elucidation by Experimental and Molecular Dynamics Simulation Study
(American Chemical Society, 2024) Sushanta Kumar Mohapatra; Indrajit Tah; Margit Fabian; Saswata Chakraborty; Prince Sen; Krishna K Dey; Manasi Ghosh; H.S. Maharana; Annapurna Kalyandurg
Broad band transmitting glasses from visible to mid-infrared with good mechanical strength, chemical durability, glass-forming ability, and thermal stability are preferred for optics and laser technology applications. Generally, low phonon energy glasses possess an extended transmission cutoff toward mid-infrared, but at the same time, retention of other desired properties is challenging for the researchers. In this work, we have shown that mixed alkaline earth (Ba/Sr) would have the potential to improve overall glass properties while retaining its low phonon energy when CaO is partially substituted by BaO/SrO in calcium magnesium zinc silica-aluminate (CMZSA) glass. Quantitative structure analysis of its role in glass properties has been carried out using molecular dynamics (MD) simulation and experimental techniques. This study reveals that Al and Si mainly attained fourfold coordination, while Zn and Mg majorly existed in Al-O-Zn/Mg triclusters. The Ba2+ ions play almost equal roles as charge compensators and network modifiers, while Sr2+ ions play a larger role in charge compensation. As a result, the SrO-added glass leads to the highest bridging oxygens as compared to others and corroborates with improved optical, thermal, and mechanical properties. Hence, the SrO-added glass shows the most stable network connection and improved overall glass properties. © 2024 American Chemical Society.
Tunable, efficient, ultrafast broadband nonlinear optical properties of TiO2–loaded complex phosphate glasses
(Elsevier Ltd, 2023) Jagannath Gangareddy; Hamad Syed; Saswata Chakraborty; Prince Sen; Manasi Ghosh; Krishna Kishor Dey; K. Bhattacharyya; K. Annapurna; Venugopal Rao Soma; Amarnath R. Allu
On account of their excellent optical transparency from ultraviolet to far infrared spectral regions, phosphate glasses have become interesting nonlinear optical (NLO) materials for photonic nonlinear devices. However, small NLO coefficients tend to limit the usage of phosphate–based glasses in nonlinear photonic devices. Herein, we explored the NLO tunability in multicomponent phosphate glasses by increasing the coordination of orthophosphate (PO4)3– structural units with a great number of AlO4 groups through the addition of titanium dioxide (TiO2) in the composition. The NLO absorption and refraction characteristics were ascertained using open and closed–aperture Z–scan configurations respectively in a broadband spectral region ranging from 400 nm to 1200 nm under an ultrafast regime. The Z–scan results illustrate the increase of nonlinear susceptibility of glasses with titanium dioxide content in the composition due to the formation of non–π–conjugated orthophosphate groups which are in connection with AlO4 units. Typically, at 400 nm excitation, the NLO susceptibility improved by 119.91% upon addtion of 5 mol% of TiO2. The outcomes of the study acknowledge a new approach for conceiving highly NLO active phosphate glasses while maintaining deep–ultraviolet transparency through the polymerization of (PO4)3−groups. Consequently, the strategy explored in this work might pave the way for achieving the high NLO features of phosphate–based glasses to excel in their usage in data storage, signal transmission, optical limiting, and harmonic generation functionalities. © 2023 Elsevier Ltd