Department Of Physics
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Item Thermophysical Assessments on Self-Assembled Tellurium Nanostructures(American Chemical Society, 2023-09-01T00:00:00) Sudheer, Manjima; Rani, Pinki; Patole, Shashikant P.; Alegaonkar, Prashant S.Thermal properties of self-assembled nanostructures are of great importance to explain the structural phase transformation phenomenon. We report on the thermophysical assessments on tellurium nanostructures (TeN) that have been prepared using a facile wet-chemical technique by admixing precursor sodium telluride (Na2TeO3) and sodium molybdate (Na2MoO4) catalysts in hydrazine hydrate solution and heated at 120 �C, over 5-7 h. The extracted products (interval: 0.5 h) were subjected to a number of spectro-microscopic techniques including thermal measurements. Under identical growth conditions, the morphology of TeN was found to be transformed from Te nanotube (TT) to Te nanoflake (TF) at 6 h. Analysis revealed that Mo participated actively during 6 h of growth time, thereby making bonds with oxygen and the Te host lattice. At the vicinity of the phase transformation, Mo acquired an interstitial position in the hexagonal motif due to enhancement in catalytic efficiency that led to the formation of MoO2- moieties, which transiently reacted with host lattices resulting in surface charging of the tubes. This, in turn, created the coalescing effect with neighboring colloidal tubes through the van der Waals interaction. Thermal properties such as thermal conductivity, effusivity, diffusivity, and specific heat studied for TeN showed prominent surface effects. The increased surface area and enhanced amount of polycrystallinity resulted in unprecedently low thermal properties of TF due to severe phonon confinement. � 2023 American Chemical Society.Item Insight into use of biopolymer in hybrid electrode materials for supercapacitor applications�A critical review(American Institute of Physics Inc., 2023-05-12T00:00:00) Tanwar, Shweta; Sharma, A.L.The shortage of natural resources due to the progression of the human population and environmental pollution has become crucial concern topics to resolve. One of the best ways to resolve this is to develop renewable energy-based storage systems. Supercapacitors are emerging as promising storage systems via providing rapid charging/discharging and high power delivery, but there is a need to explore low-cost, environment-friendly, non-toxic, abundant, and biodegradable electrode materials for supercapacitors. In this regard, biopolymers are observed to be popular for storage applications as they are of high porosity, cost-effective, easily available, low-weight, and environment friendly and have biodegradability properties. The biopolymer-based electrode has a desirable morphology and high surface area and exhibits admirable electrochemical properties. The focus of this report is to highlight (i) the inclusive details of supercapacitors and their types along with strategies to improve their electrochemical performance, (ii) biopolymers and their types used for supercapacitor applications, (iii) various synthesis routes that could be adopted for designing electrode materials based on biopolymers for supercapacitors, and (iv) challenges and future scope of biopolymers as the electrode material in supercapacitor applications. The detailed study here in this report is found to be a topic of interest for the scientific community to fabricate and prepare low-cost, eco-friendly, high electrochemical performance exhibiting electrode materials for supercapacitor applications. � 2023 Author(s).Item Enhanced photocatalytic activity of BiOBr/ZnWO4 heterojunction: A combined experimental and DFT-based theoretical approach(Elsevier B.V., 2023-03-28T00:00:00) Andrade, Alana O.C.; Lacerda, Lu�s Henrique da Silveira; Lage J�nior, M.M.; Sharma, Surender K.; Maia da Costa, M.E.H.; Alves, Odivaldo C.; Santos, Evelyn C.S.; dos Santos, C.C.; de Menezes, A.S.; San-Miguel, Miguel Angel; Filho, Francisco Moura; Longo, Elson; Almeida, Marcio A.P.We report a successful fabrication of BiOBr/ZnWO4 heterojunction with enhanced photocatalytic performance for degrading Rhodamine B dye validated by joint experimental and theoretical approaches. The structural and microstructural analysis indicate that the heterostructures consist of a mixed tetragonal/monoclinic phase with enhanced surface area, which is crucial for photocatalysis. The results indicate increased photocatalytic activity for heterojunctions since BiOBr/ZnWO4 heterostructure showed a better degradation rate for Rhodamine B dye as compared to BiOBr due to higher surface area, pore size, and better photogenerated electron-hole pair separation efficiency. Additional analyses using isopropanol, benzoquinone, and sodium azide scavengers analysis were performed, showing that superoxide radicals (O2?) as the main responsible for the photocatalytic degradation of investigated materials. The theoretical analysis offers a complete overview of the composition and electronic structure of the interface. � 2023 Elsevier B.V.Item Synthesis, phase confirmation and electrical properties of (1 ? x)KNNS?xBNZSH lead-free ceramics(Springer, 2022-02-02T00:00:00) Kumar, Amit; Kumari, Sapna; Kumar, V.; Kumar, Prashant; Thakur, Vikas N.; Kumar, Ashok; Goyal, P.K.; Arya, Anil; Sharma, A.L.In the present work, lead-free piezoelectric ceramics (Rx)(K0.5Na0.5)(Nb0.96Sb0.04O3)?x(Bi0.5Na0.5)(Zr0.8Sn0.1Hf0.1)O3 [abb. as (Rx)KNNS?xBNZSH, 0 ? x ? 0.04] were prepared via solid-state sintering technique. The thermal behavior of mixed powders has been investigated for x = 0, 0.02, and 0.04 using TGA-DSC analysis to estimate the calcination temperature. The structural, morphological, dielectric, ferroelectric and piezoelectric properties are analyzed through the appropriate characterization techniques. The X-ray diffraction (XRD) patterns demonstrate a pure perovskite phase structure for all the sintered samples. Further, the coexistence of rhombohedral to orthorhombic (R-O) phase is observed in ceramic sample with x = 0.02. The morphology of all the sintered samples exhibits an inhomogeneous, dense microstructure with the rectangular grain, while for x = 0.02, a relatively homogeneous distribution of grains is observed. BNZSH doping decreases the average grain size from 2.22 to 0.33�?m for x = 0 to x = 0.04, respectively. Owing to the presence of multiple-phase coexistence as well as the improved microstructure and enhanced dielectric properties (dielectric constant ?r = 1080, ?max = 5301; Curie temperature - TC ~ 317��C; dielectric loss - tan? ~ 6%) the ceramics with x = 0.02 has been found to have a large piezoelectric coefficient (d33) of ~180 pC/N, remnant polarization (Pr) ~ 16.7 �C/cm2 and coercive field (Ec) ~ 10.7�kV/cm. We believe it will expand the range of applications for KNN-based ceramics. � 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.