https://dspace.iiti.ac.in:8080/jspui/handle/123456789/9662 2026-05-12T17:10:14Z https://dspace.iiti.ac.in:8080/jspui/handle/123456789/14296 Title: Development of solid state fluorescent materials and their application in water-repellent cotton fabrication and corrosion protection Authors: Yadav, Saurav Kumar; Kumar, C. Karan; Dubey, Mrigendra [Guide] Abstract: ------ 2023-12-17T00:00:00Z https://dspace.iiti.ac.in:8080/jspui/handle/123456789/10615 Title: Machine learning based material selection: quaternary chalcogenides for energy applications Authors: Kaushik, Devashish; Kushwaha, Ajay Kumar [Guide] Abstract: Photovoltaics (PV) and Water Splitting (WS) are critical target areas for material development. Machine Learning (ML) is the only viable method for finding suitable candidates from the immense number of possible compounds. As a class of materials, Quaternary Chalcogenides appear quite promising for potential use in these applications. However, only a small subset of them have been studied. This work is the first ML-based material selection analysis for these materials, focusing on A2BCX4-type compounds. The band gap was the primary property targeted in the study due to its fundamental role in determining a material’s suitability for these applications. The band gap prediction performance achieved by ML models was competitive with those reported for other classes of compounds in the existing literature. The relationship between the total energy and space group of Quaternary Chalcogenides was also explored, including a proposed protocol for using our ML models for total energy to determine the space group given only the composition of the compound. In addition, the relationship between various elemental properties and band gap was investigated via SISSO. For this purpose, we developed our own implementation of this algorithm in Python. The heuristic formulae obtained allow computationally inexpensive estimation of the band gap. An extremely simple but versatile model was used to understand the band gap change Quaternary Chalcogenides and justify the SISSO models. The understanding gained via these formulae has potential applications in band gap tuning. These results were used to identify candidate compounds with possible use in 3 areas - PV Solar Cells, Photocatalytic WS, and Photoelectrochemical WS. 2022-05-27T00:00:00Z https://dspace.iiti.ac.in:8080/jspui/handle/123456789/10467 Title: Synthesis of multi colour emissive tunable carbon dots: anti-counterfeit and optoelectronic applications Authors: Saksham; Dubey, Mrigendra [Guide] Abstract: The tunable photoluminescence (PL) carbon dots (CDs) are synthesized using one-pot solvothermal techniques by varying the –NH2, -COOH, and –CH2- ration on the precursor. The carbon dots were synthesized by using 1, 2, 3, 4- butanetetracarboxylic acid (BTC) along with two groups of reagents: (group 1) aromatic compound by varying the NH2: COOH ratio, (group 2): By varying the –CH2- on the non-aromatic compound. These carbon dots show white (ABA-CD, ED CD), purple (AIA-CD), blue (PPD-CD, HYD-CD), and cyan (DBA-CD) colour fluorescence under a single wavelength UV light. The as-obtained carbon dots are further characterized by using 1H NMR, 13C-NMR, MS, FTIR, UV-Vis, and PL. The synthesized carbon dots show an optimal fluorescence quantum yield of 37.41% for purple colour emitting carbon dot AIA-CD. The red shift photoluminescence emission behaviour of purple (AIA-CD), blue (PPD-CD), and cyan colour (DBA-CD) emitting carbon dots can be attributed to the reduction in the bandgap energy from 4.14 to 3.52 to 3.46 eV respectively. Further, the ESI-MS, and 13C-NMR shows that carbon dots can possibly have polymeric structure, and are formed by condensation, and dehydration reactions, along with that carbon dots formed with group 2 precursors have more percentage of sp3 carbon domains as compared to the carbon dots from group 1. The synthesized carbon dots are further used to manufacture a UV Converting torch which is first of its own kind including white light. Further, due to stability, invisibility under daylight, and low cost these carbon dots are further used for anti-counterfeiting, and information storage applications. 2022-05-26T00:00:00Z https://dspace.iiti.ac.in:8080/jspui/handle/123456789/10466 Title: Fabrication and characterization of eutectic high entropy alloys Authors: Prasad, Nandikandi Bhanu; Tejavath, Vasu; Maurya, Ram Sajeevan [Guide] Abstract: High entropy alloys (HEA) are a new class of metals that have proven the ability to outperform traditional alloy systems in terms of physical and mechanical qualities. However, HEAs can have either high strength or high ductility, and achieving both at the same time is still a difficult task. HEA’s poor castability and compositional segregation are further impediments to their technological applicability. To address these issues, we presented a technique for designing HEAs based on the eutectic alloy idea. Due to the fine distribution of phases, the development of eutectic microstructure in high entropy alloys can aid in getting an even better combination of mechanical qualities. Using the above-mentioned concept, we designed Al5(VCr)46.36(CoNi)48.64 eutectic high entropy alloy but it did not form eutectic. One possible explanation for this could be the Al content. We need to vary the Al content lower than 5 at% and more than 5 at% systematically to see the eutectic morphology. The DSC too further evidence that there is a large region of melting indicating multiple phases, when observed in SEM micrograph, able to guess that it is a primary FCC followed by some solid-state transformation as indicated by the continuous pores. 2022-05-20T00:00:00Z