Journal Articles
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Item Sodium ion incorporated alumina - A versatile anisotropic ceramic(Elsevier Ltd, 2019) Pujar, P.; Gupta, B.; Sengupta, P.; Gupta, D.; Mandal, S.The present article is a review of crystal structure dependent anisotropic properties of β and β″-phases of sodium ion incorporated alumina. The anisotropy in electrical properties such as ionic conductivity and dielectric permittivity is due to the layered structure. Conducting plane between two consecutive spinel aluminas constituting loosely bound mobile sodium ions, promote ionic conductivity in the parallel direction. In contrary, the restricted movement of ions in the orthogonal direction brings about polarization giving it directional dielectric property. High ionic conductivity of 1.3 S/cm and large dielectric constant of ˜ 200 are reported. Exchanging sodium ions with different cations, such as potassium and lithium, results in similar anisotropy. The processing of β and β″-phases along with metastability of intermediate mullite phase is described in the current review. In addition, the applications of sodium ion incorporated aluminas, such as solid electrolyte in batteries, thin film transistors and gas sensors are discussed. © 2019 Elsevier LtdItem A roadmap to UV-protective natural resources: Classification, characteristics, and applications(Royal Society of Chemistry, 2021) P, P.; Salian, A.; Dutta, S.; Mandal, S.Alongside the innumerable benefits of solar rays, the adverse effects of ultraviolet (UV) radiation must be considered. All organisms are subjected to the deleterious effects of UV radiation, particularly UVA (315-400 nm) and UVB (280-315 nm). Continuous UV exposure leads to skin cancer, erythema, and sunburn mediated by reactive oxygen species (ROS). Photoprotection is hence an indispensable feature in all strata of the ecosystem across the microbial, plant, and animal kingdoms, especially under the present circumstance of increased ozone depletion. Photoprotective compounds, like gadusols, mycosporine-like amino acids (MAAs), scytonemin, phenolic compounds like flavonoids, anthocyanins, lignin, and less-explored compounds like sporopollenin, parietin, and usnic acid have been identified in various organisms. Accumulation of photoprotective pigments is a universal mechanism of passive protection against UV, developed by organisms during the early stages of their evolution. Furthermore, many of these compounds contribute to antioxidant and anti-inflammatory actions, which offer additional protection. In this review, the attributes of naturally available UV-screening compounds are investigated. Their taxonomic diversity, mechanism of UV absorption, extraction, and characterization techniques are discussed. In the wake of recent studies that indicate free radical generation in inorganic sunscreen compounds like TiO2 and ZnO, natural products have become a necessity. Insights into natural compounds for photoprotective functions in commercial applications like cosmetics and textiles are also reviewed. Biocompatibility and minimal side effects of these natural compounds open the gateway into an era of green products in the arena of photoprotection. © the Partner Organisations.Item Entropy stabilized multicomponent oxides with diverse functionality–a review(Taylor and Francis Ltd., 2022) Salian, A.; Mandal, S.Over the last few years, high-entropy oxides (HEOs) are subjected to considerable scientific scrutiny due to their exceptional characteristics, tunable properties displaying remarkable performance including colossal dielectric constant, low electrical and thermal conductivity, high-temperature phase stability, excellent magnetic, structural optical properties and extraordinary catalytic behavior. The single-phase crystal structure of multicomponent oxides is stabilized via configurational entropy (S config). An incrementation in the number of elements magnifies S config which dominates the free energy landscape, overcomes enthalpy in Gibb’s free energy, and reaches a maximum magnitude while entire elements are in equiatomic fractions. Therefore, accurate control of configurational entropy is the main motive force used to achieve phase pure HEOs by the incorporation of more than four cations in the system in equiatomic proportions with random distributions. HEOs are becoming hotcakes in the field of research as it emphasizes on compositions proximally near the centers of the multicomponent phase diagram, where unexpected behaviors can be anticipated. Thus, presenting a crucial research frontier for the material scientists to explore. As the novel design approach of entropy stabilization is still immature, these new oxide candidates can be engineered for practical applications in batteries, capacitors, nuclear reactors, and thermal barrier coatings. This review addresses the properties like electrochemical, electrical, magnetic, mechanical, catalytic, thermal, etc., of HEOs to date, with additionally focusing on their classification, theoretical predictions, and fundamental understanding of entropy engineering including entropy dominated phase stabilization effect. © 2021 Taylor & Francis Group, LLC.Item Review on the deposition, structure and properties of high entropy oxide films: current and future perspectives(Springer, 2022) Salian, A.; Mandal, S.High entropy oxides (HEOs) have captivated significant concentration due to their unique properties. Manipulation of configurational entropy is the main key for extraordinary behaviours, leading to unprecedented material design and innovations. Substantial research has been conducted on HEO bulk systems, but films are still in the cradle stage. Inspired by the ground-breaking results of HEOs, a novel form of films named high entropy oxides films (HEOFs) are being fabricated. The focus in this review is on the fabrication process, structure and properties of HEOFs with attention to their strengths and liabilities. Iconic investigations from recent articles are highlighted. The first overview is provided on how HEOFs are fabricated and interesting phenomena such as the impact of processing parameters, the role of dopants on the film are discussed. This review also highlights the structural–microstructural appearance and physical properties, concluding with future possibilities and applications. © 2022, Indian Academy of Sciences.Item A revisit to solution-processed zirconia and its stabilized derivatives as protective coatings for base-stainless steel(Taylor and Francis Ltd., 2023) Vardhan, R.; Eknath Chaudhari, N.; Pujar, P.; Mandal, S.Stainless steel (SS) is a well-known engineering material which is predominantly used in multitudinous applications; however, the disquieting entity is its deteriorative nature triggered by the corrosion in biological, chemical, and high-temperature surroundings. Zirconia is a noteworthy material because of its remarkable mechanical, thermal, and biocompatible properties. To further improve the properties, the high-temperature phases of zirconia are stabilized at room temperature. Zirconia and its stabilized derivates are favored candidates as protective coatings for SS. They offer high resistance, allow them to perform in corrosive, sensitive environments, and augment the longevity, serviceability of SS. Deposition of zirconia/stabilized-zirconia (Z/s-Z) coatings is accomplished using vapor-phase methods, which are capital-intensive; they comprise high vacuum and processing time, confined space, and more energy consumption, resulting in fabrication cost maximization. Alternatively, solution-phase deposition methods are advantageous, effortless, and capable of depositing on large-area substrates, promising to lessen fabrication costs and to enhance yield. Solution-phase methods, namely dip, spray, and spin coatings, have been investigated to produce effective, high-grade Z/s-Z coatings on SS. This review summarizes the utilized precursors, solvents, and process parameters for depositing Z/s-Z coatings on different types and grades of steel through mentioned solution-phase methods, respectively. The review emphasizes the researched potential applications of solution-phase processed Z/s-Z with a particular role as a protective coating on SS-based implants, surgical instruments preserving corrosion resistance, nontoxicity and biocompatibility in the body fluids. The review also highlights the defensive property of solution-phase processed Z/s-Z coatings to the underneath SS against corrosive chemical media (acids like H2SO4, HCl, HNO3; chlorides like NaCl and toxic gases like H2S, coal). The oxidation protection to the beneath SS by the mentioned coatings in aggressive high-temperature surroundings is also focused in the present review. © 2022 Taylor & Francis Group, LLC.Item A review on high entropy silicides and silicates: Fundamental aspects, synthesis, properties(John Wiley and Sons Inc, 2023) Salian, A.; Sengupta, P.; Vishalakshi Aswath, I.; Gowda, A.; Mandal, S.Metal silicides and silicates belong to the silicon-based non-oxide and oxide ceramics family with exceptional properties. Silicides face fatal oxidation at low temperatures and intrinsic brittleness, whereas silicates face instability in phase at high temperatures which restricts its usage in vast engineering applications. Hence, the ceramic community introduced the concept of high entropy in metal silicides and silicates. Since 2019, high entropy silicides and silicates, a multicomponent system, have created new avenues for materials discovery and design. High entropy silicides displayed elevated properties than the traditional silicides aiming its applications in microelectronic, high-temperature oxidation resistance coatings, and structural materials. Similarly, high entropy silicates displayed improved properties than the traditional silicates making them the most promising materials for environmental and thermal barrier coating applications for hot section components in gas turbines. The review focuses on specific case studies to emphasize the latest research and developments in high entropy silicides and silicates. Synthesis approaches employed in developing high entropy silicides and silicates and their structural and microstructural outcomes are addressed. The possible application is predicted based on the overview of the properties explored to date. The review concludes with future possibilities offered by the high entropy silicides and silicates. © 2023 The American Ceramic Society.Item Bio-Inspired, Ultra-hydrophobic Natured Durable Thermal-Sprayed Ytterbium-Oxide Coatings: Review and Perspectives(Taylor and Francis Ltd., 2024) Praveen, L.L.; Kailasam, K.; Vardhan, R.V.; Mandal, S.Ever since the discovery of ultra-hydrophobicity in lotus leaf, rigorous experiments have been carried out to replicate and understand its wetting nature using ceramic oxide based coatings on various substrates. Enormous applications dealing with ultra-hydrophobic nature have been explored which led to the discovery of intrinsic hydrophobic nature in rare-earth oxides. Several studies reported intrinsic hydrophobic behavior exhibited by rare earth oxides. Among all rare earth oxides, ytterbium-oxide (Yb2O3) has numerous applications in different fields because of its ability to phase change with pressure, abrasion resistance, high hardness and melting point. This review gives a basic understanding of wettability studies carried out on Yb2O3 coating via the solution precursor plasma spray (SPPS) technique outlined in the literature and aims to understand the mechanism of post-processing treatments, revealing the conditions affecting the reversible wettability. Additionally, the mechanical durability tests performed on thermal-sprayed Yb2O3 coatings are summarized along with the cost-effective approach of SPPS technique over other plasma spray techniques. The ultra-hydrophobicity in Yb2O3 coatings and its existing applications propels the development of novel device-designing strategies in the field of bio-sensing and oil-water separation. © 2024 Indian Ceramic Society.Item In the present study, various ocean wave parameters are estimated from theoretical Pierson-Moskowitz spectra as well as measured ocean wave spectra using backpropagation neural networks (BNN). Ocean wave parameters estimation by BNN shows that the correlations are very close to one. This substantiates the use of neural networks (NN). For Indian coast, Scott spectra are used as it reasonably represents the measured spectra. The correlations of NN and Scott spectra are also compared. Once the network is trained, the ocean wave parameters can be estimated for unknown measured spectra, whereas significant wave height and spectral peak period are required to first generate the Scott spectra and then estimate other ocean wave parameters. © 2005 Elsevier Ltd. All rights reserved.(Ocean wave parameters estimation using backpropagation neural networks) Mandal, S.; Rao, S.; Raju, D.H.2005Item Neuro-fuzzy based approach for wave transmission prediction of horizontally interlaced multilayer moored floating pipe breakwater(2011) Patil, S.G.; Mandal, S.; Hegde, A.V.; Alavandar, S.The ocean wave system in nature is very complicated and physical model studies on floating breakwaters are expensive and time consuming. Till now, there has not been available a simple mathematical model to predict the wave transmission through floating breakwaters by considering all the boundary conditions. This is due to complexity and vagueness associated with many of the governing variables and their effects on the performance of breakwater. In the present paper, Adaptive Neuro-Fuzzy Inference System (ANFIS), an implementation of a representative fuzzy inference system using a back-propagation neural network-like structure, with limited mathematical representation of the system, is developed. An ANFIS is trained on the data set obtained from experimental wave transmission of horizontally interlaced multilayer moored floating pipe breakwater using regular wave flume at Marine Structure Laboratory, National Institute of Technology Karnataka, Surathkal, India. Computer simulations conducted on this data shows the effectiveness of the approach in terms of statistical measures, such as correlation coefficient, root-mean-square error and scatter index. Influence of input parameters is assessed using the principal component analysis. Also results of ANFIS models are compared with that of artificial neural network models. © 2010 Elsevier Ltd. All rights reserved.