http://20.198.91.3:8080/jspui/handle/123456789/211 2026-04-05T19:41:40Z http://20.198.91.3:8080/jspui/handle/123456789/9038 Title: Design and characterization of a new high entropy perovskite oxide for efficient thermoelectric application Authors: Roy, Mousom Abstract: This thesis presents a comprehensive exploration of perovskite materials with a focus on novel high entropy perovskites (HEPs) and their potential as thermoelectric materials. Six distinct perovskite compositions were synthesized, characterized, and evaluated, culminating in the design and creation of two innovative high entropy perovskites, HEP-1 and HEP-2. The ABX3 structure, a hallmark of perovskite materials, was reimagined in HEP-2 with an unprecedented configuration involving La and Sr in site A, and Fe, Mn, Cu, Ni, Co, and Cr in site B, along with oxygen in site X. The synthesis methodology employed a tailored sol-gel approach, followed by solvent-aided grinding and calcination. The rationale behind the design was to simultaneously enhance electrical conductivity while mitigating thermal conductivity through phonon dispersion mechanisms, with the ultimate goal of improving the power factor and figure of merit—a vital aspect of thermoelectric performance. Characterization efforts encompassed structural, chemical, and physical analyses of the synthesized samples, including thin films and pellets. An Arduino-based device setup was meticulously crafted and customized from scratch to facilitate real-time data collection and analysis of thermoelectric properties. This experimental arrangement underscored the commitment to pushing the boundaries of thermoelectric research and technology. The findings from this research highlight the relationship between composition, crystal structure, and thermoelectric performance. The synthesis of novel high entropy perovskites, especially the groundbreaking HEP-2 structure, offers new avenues for enhancing energy conversion and harvesting technologies. The optimization of power factor and figure of merit through improved electrical conductivity and tailored phonon dispersion holds substantial promise 2023-01-01T00:00:00Z http://20.198.91.3:8080/jspui/handle/123456789/9037 Title: Kinetic modelling and antibacterial study of drug released from clay layers and lab synthesized transdermal patch Authors: Gayen, Aditya Debapriya Abstract: In the world of medicine, a class of drug called antibiotics is used to treat bacterial infections. They function by either eradicating the bacteria or slowing their growth, so preventing the spread of the infection. Clay has become a material that shows promise for drug loading. Large surface area, ability to produce nanoscale particles or layered structures, and high drug-loading capacity are all characteristics of clay. Drug molecules can be stored in the interlayer gaps of clay minerals, where they are shielded from deterioration and given greater stability. The Clay minerals like montmorillonite, kaolinite, and halloysite have these properties. Here Gatifloxacin an antibiotic drug is loaded into montmorillonite clay layers. Characterization methods like FTIR, XRD and SEM are conducted, for further confirmation and efficacy of the loaded drug, different culture of the bacteria (Staphylococcus aureus) which is a commonly found bacteria was made and the zone of inhibition of the bacteria upon application of drug was observed. The release behaviour of medications from different drug delivery devices may be predicted using release kinetics. To characterise the release kinetics and forecast the release behaviour under various situations, mathematical models such the zero-order, first-order, Higuchi, and Korsmeyer-Peppas models are frequently utilised. Burst and sustained releases were conducted to observe which model fits the best. The drug loaded clay was incorporated into patches and their release kinetics as well as the antibacterial efficacy test were performed. It was observed that the patches were successful to inhibit the bacterial growth. 2023-01-01T00:00:00Z http://20.198.91.3:8080/jspui/handle/123456789/9035 Title: Synthesis,characterization and investigation on optical properties of sodium cerium double tungstate [nace(wo4)2] nanomaterials Authors: Biswas, Koninika Abstract: The study given in the thesis “Synthesis, Characterization and Investigation on Optical Properties of Sodium Cerium Double Tungstate [NaCe(WO4)2] Nanomaterials” is primarily concerned with two segment: first, the synthesis of scheelite material NaCe(WO4)2 and second finding the changes in optical properties. Rare earth oxide materials have potential applications in optoelectronics owing to their unique optical properties that arise from 4f–5d electronic transitions. Optical properties such as Photoluminescence (PL) of these oxide materials are found to be determined by their crystallographic features as well as type of activator ion and sensitizer ion residing in the host lattice. Alkali rare earth double tungstate with the general formula ARE(WO4)2, where A is an alkali metal ion, RE is a rare earth ion, and M = W/Mo, were known to adopt the Scheelite-like crystal structure. These materials have received a lot of interest owing to their structural stability and tenable optical properties. The primary goal is to synthesize NaCe(WO4)2 using Hydrothermal Method. Their structural and optical properties have been researched and characterized. The control of its size and form was achieved by adjusting the preparation parameter. 2023-01-01T00:00:00Z http://20.198.91.3:8080/jspui/handle/123456789/9032 Title: Low power and stable rram device based on α-in2se3 nanosheet / γ-in2se3 nanoparticle homojunction embedded in or ganic polymer (pmma) for non volatile memory application Authors: Ray, Gourav Abstract: The Von Neumann Architecture has become more of a problem whose severity increases with every newer generation of the central processing unit. To solve the issue, memristors and other novel electronic heterojunctions are expected to become the most promising candidate. Resistive switching random access memory (RRAM) device is one of those promising candidates for next generation non volatile memory due to its high stacking density, Low power consumption, high scalability, fast fabrication process and multistate behaviors. The resistive switching (RS) behavior has been observed in the wide range of binary/ multinary oxides or chalcogenides and some or-ganics in recent years. Here in, for the first time novel α-In2Se3 nanosheet/ γ-In2Se3 nanoparticle homojunction embedded in poly-methyl methacrylate (PMMA) is employed as an active layer of Resistive random access memory device (RRAM) for non volatile memory application. This homojunction is synthesized via simple solvothermal method and dispersed in PMMA solution with different weight concen-trations. Several characterizations such as Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV-Visible spectroscopy (UV-Vis), High-resolution transmission elec-tron microscopy (HRTEM), Raman spectroscopy are performed for analysis and perfect study of the synthesized material. The composite sample is deposited on a FTO coated transparent glass substrate to form Al/ In2Se3@PMMA/ FTO device. I-V characterizations of the cell reveal a for-mation free, bipolar, non volatile and multilevel Resistive-switching (RS) properties for memory application. Variation of In2Se3 concentration is performed to get the best performing device. The best device shows a significantly large resistance ON/OFF ratio of 104, low operating voltage (<2V) and long retention time (more than 9000 s) at room temperature. After the analysis of ex-perimental data, the conduction mechanism for our In2Se3-PMMA based RRAM device is ex-plained by trap-assisted space-charge limited conduction (SCLC) for high resistive state (HRS) and ohmic conduction for low resistive sate (LRS). The proposed RS active material is a promising candidate for future artificial neural systems for mimicking the characteristics of human memory. 2023-01-01T00:00:00Z