http://dspace.dtu.ac.in:8080/jspui/handle/repository/18356 Projects reports of M Sc course 2026-04-28T04:03:29Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22247 Title: FABRICATION AND CHARACTERIZATION OF A FLEXIBLE PIEZOELECTRIC GENERATOR BASED ON POTASSIUM SODIUM NIOBATE (KNN) DOPED WITH LITHIUM, ANTIMONY (LISB) /PVDF COMPOSITE FILM Authors: KUMAR, ABHISHEK; YADAV, AKSHAY Abstract: In this work, we have fabricated [(0.95(K0.48Na0.52)NbO3)–(0.05)(LiSbO3)]/PVDF piezoelectric generator (PEG), whereas a polymer matrix, PVDF is employed and KNN-LiSb as a filler piezoelectric substance. The stated objectives of adding lithium and antimony to KNN powder are to improve the piezoelectric properties. The KNN-LiSb/PVDF composite films have been prepared with various concentrations of KNN-LiSb ceramic particles (0%,5%,10%,15%, and 20% in PVDF) by using the drop-casting method. The phase and structural analysis of the piezoelectric composite film was investigated by XRD and FTIR. SEM (Scanning Electron Microscopy) analysis of the morphology of composite films revealed that the ceramic particles were dispersed equally throughout the PVDF matrix. Furthermore, the prepared generator's efficiency in harvesting energy was assessed by Electrodynamic Vibrator Shaker to apply pressure, followed by an estimation of the resulting voltage and short- circuitry current. The 15% KNN-LiSb /PVDF composite film-based Piezoelectric Generator could also induce maximum resulting voltage and short-circuiting current of approx.15.47 V and 2.14 μA, respectively. The current work showed that lead-free piezoelectric ceramics can be modified with suitable dopants to provide high-performance PEG. Ultimately, the synthesized flexible piezoelectric generator's outputs indicate that there are significant possibilities for application in wearable and self-powered electronic devices 2023-05-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22234 Title: METAMATERIAL ABSORBERS : REVIEW Authors: SEN, DEVANSHI Abstract: Metamaterials are man-made structures that exhibit extraordinary electromagnetic properties not typically found in natural materials. These unique materials hold great promise for a variety of advanced applications, one of the most prominent being metamaterial absorbers. The design of such absorbers relies on the simultaneous excitation of electric and magnetic dipole resonances. A standard metamaterial absorber consists of a three-layer structure: a top layer featuring metallic patterns at subwavelength scales, a metallic ground plane at the bottom, and a dielectric (insulating) layer sandwiched in between. The top patterned layer acts as an electric resonator, interacting with the electric field of incoming electromagnetic waves. Meanwhile, the magnetic response arises from the interplay between the two metallic layers and the intervening dielectric. To block wave transmission, the ground layer must be thicker than the skin depth. By adjusting the geometry of these structural components, one can tune the effective permittivity and permeability, allowing the structure to match the impedance of free space, which results in perfect absorption at specific wavelengths. In recent years, the need for chemical and biological sensing has driven the development of mid-infrared perfect metamaterial absorbers. This thesis focuses on literature review of various metamaterial absorbers and it’s other application. 2025-06-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22222 Title: STRUCTURAL AND OPTICAL PROPERTIES OF SnS2 NANOSHEETS FOR OPTO- ELECTRIC DEVICES Authors: KUMARI, PREETI; MORYA, RIMPAL Abstract: Tin disulfide (SnS2) is a promising material for applications in hydroelectric cells, photovoltaics, photodetectors, and energy storage owing to its layered structure, excellent optical properties, electrical and high chemical stability. In this study, SnS2 nanosheets were fabricated using the sol-gel technique, a method known for its efficiency in producing high-purity nanostructures on a large scale at a reasonable cost. To produce the final SnS2 nanosheets, a precursor solution consisting of Sn and sulfur sources were prepared. This was followed by careful hydrolysis of Tin (IV) chloride pentahydrate with thiourea, forming a gel, which was dried and annealed to obtain crystalline SnS2 nanosheets. X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), UV- Vis spectroscopy, and Photoluminescence spectroscopy (PL) were used to investigate the structural, morphological, chemical bonds, optical and electrical characteristics of the produced SnS2. While TEM showed a layered and distinct nanostructure, the XRD investigation verified the production of a pure hexagonal SnS2 phase. UV-Vis spectroscopy estimates a band gap of 2.37 eV. PL spectra showed a prominent emission peak at 699 nm, suggesting a direct bandgap transition suitable for optoelectronic devices. The chromaticity diagram was created using PL data indicate the blue color emitted by the light source which can be used in electro-optical devices. FTIR analysis of sol-gel-synthesized SnS2 confirmed the presence of Sn-S bonds, indicating successful compound formation. According to these estimations, the optical band gap falls within the range appropriate for optoelectronic applications. The results show that the sol-gel process is a productive way to create high-quality SnS2 with adjustable characteristics, making it a good option for next-generation energy harvesting and electronic devices. 2025-05-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22035 Title: ELECTROMAGNETIC WAVE PROPAGATION THROUGH A PLASMA SLAB: ANALYSIS OF REFLECTION, TRANSMISSION AND ABSORPTION CHARACTERISTICS FOR VARYING MEDIUMS Authors: SHARMA, ADITI; DIYA Abstract: This paper presents a theoretical investigation of the reflection (R), transmission (T), and absorption (A) coefficients of electromagnetic waves interacting with a slab of plasma, complex dielectric and hydrogel. Starting with the calculation of the net phase acquired by the wave upon entering the slab, we derive the wave vector components and the dispersion relation governing the system. Using these, analytical expressions for R, T, and A are obtained by applying Maxwell’s boundary conditions at the interfaces. Numerical simulations are carried out for various materials, including hydrogels and conventional dielectric media, to study and compare their electromagnetic responses. The results reveal distinct differences in wave behaviour due to varying medium-induced modifications in plasma permittivity. Theoretical predictions are validated by comparison with existing experimental data, demonstrating good agreement and highlighting the significant role of diverse mediums in controlling wave propagation. This work provides insights into the design of plasma-based devices for electromagnetic filtering and shielding applications. 2025-05-01T00:00:00Z