Department of Physics
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Item Study of Electronic Performance of Ferroelectric Materials for Potential Application in Diode Based Devices(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2024) EIMAN RASHEED; CUI/SP23-RPH-020/LHR; Dr. Amna Mir; LHR TP 9640Bismuth ferrites that are doped with rare-earth and processed by sol-gel method with citric acid as a chelating agent shows a greatly enhanced ferroelectric behavior thus making these materials appropriate for diode based applications. Gadolinium, yttrium, and samarium are examples of rare-earth elements that, when added to bismuth ferrite (BiFeO₃), enhance its physical properties. The doping of Gadolinium improves bandwidth and decreases resistance, while yttrium ensures that polarization is not lost and the device stays functional regardless of frequency. On the other hand, samarium-doped bismuth ferrite has proliferated the market with its great ferroelectricity, lower leakage current and quick charge transport mechanism all integrated in it. Correlating its absorption peak of UV-Visible light at 279 nm, with a bandgap of 2.6 eV, development in devices that use light such as LED will not be a challenge, moreover, its I-V characteristic give rectifying action which is necessary for diodes operation. These results accentuate the potential of rare-earth-doped bismuth ferrites, particularly samarium-doped variants, in developments of devices such as memory units, photodiodes and devices that utilize light in an efficient manner.Item Study of Antenna Topology for Communication Applications(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2021) Ali Ahmad; CUI\FA19-RPH-054\LHR; Dr. Amna Mir; LHR TP 7269Wireless communication has a key role in the communication technology and its most of the advanced and novel techniques are based on fifth generation (5G) communication system. This fast progress in communication motivated many researchers to investigate and develop advanced technology either in hardware or software field. For 5G technology, a wideband frequency range (6GHz – 100GHz) has been focus of the study. The antenna is a basic element of the wireless communication system. An optimized design of antenna for 5G communication is most challenging field and needs continuous improvement. The main purpose of this research work is to study and design a new 5G communication module with a novel and optimized antenna design. Different parameters of the antenna are examined to approach the optimized design. This work is focused on 28 GHz band (27.5 – 29.5 GHz) to find out the optimized design using CMA (Characteristic Mode Analysis). The characteristic modes analysis is studied to characterize the resonant behavior of characteristic modes of the proposed antenna design in operational frequency range. The features required in an antenna to support a 5G communication system are satisfied in the optimized design with total gain 12 dBi and high bandwidth 2.16 GHz. To enhance the directivity of the designed antenna a 1x2 (two-element) and 1x4 (four-element) antenna arrays are optimized and studied. At the operational frequency, two-element and four-element antenna arrays achieved high bandwidth and high gain.Item Study of Rare Earth Doped Ferrites and Their Characterization in High Frequency Region(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2019) RAFIA RAEES; CIIT/FA17-RPH-029/LHR; LHR TP 5723; Dr. Amna MirCharacterization of a material at high frequency is done by the use of a transmission line (coaxial) and Vector Network Analyzer (VNA). VNA measures the S-parameters that includes xture e⁄ects. Theoretical derivation of S-paramters was done by solv- ing electric eld equations subject to boundry conditions. It is clear from obtained relations that extra phase factors are included due to coaxial cells in the measurement setup. These extra phase terms are removed by using de-embedding technique. Math- ematica software was used to carry out the mathemetical steps. After de-embedding, S-parameters of material under test are obtained. These material parameters were then solved using NRW method which is used to extract complex electromagnetic properties of prepared Strontium ferrite substituted with a rare earth material. M-type Strontium ferrite with a structural formula SrxItem Investigation and Fabrication of Piezoelectric Based Nanogenerators for Energy Harvesting Applications(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Faisal Ali; CUI/FA23-RPH- 014/LHR; Dr. Amna Mir; LHR TP 9845PENGs (piezoelectric nanogenerators) have emerged a promising technology to harvest electrical energy from mechanical stress (pressure, vibrations) to empower the small-scale electronic devices. This study focuses on the investigation and fabrication of piezoelectric- based nanogenerators for energy harvesting applications. We designed and developed nanostructured devices by manipulating the piezoelectric properties of materials NaNbO3 (sodium niobate) for efficient energy conversion. The process for the fabrication of devices involved advanced techniques including hydrothermal synthesis, ink synthesis and EHD (electrohydrodynamic) printing for thin film deposition of NaNbO3 to achieve high- performance nanostructure with enhanced piezoelectric response of material and device. The materials and nanogenerators were characterized for their electrical properties and electrical output under various mechanical conditions e.g. UV, FTIR, Raman, XRD for material and IVfor device. Experimental results demonstrated a significant output voltage. The study also demonstrated the integration of PENGs with flexible substrates and the material is environmentally friendly for wearable, implantable devices and self-powered sensors. The work highlights the nanogenerators could be a good solution for sustainable energy harvesting in next-generation electronic devices.Item Investigation and Fabrication of Triboelectric base Nanogenerators for Energy Harvesting Applications(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2025) Muhammad Bilal; CIIT/FA23-RPH-026/LHR; Dr. Amna Mir; LHR TP 9855The increased need for renewable and sustainable energy sources has led to the idea of the Triboelectric Nanogenerators (TENGs), which are considered one of the promising sources of energy that can be converted into electricity at low frequencies. This article reports the design synthesis and fabrication of a compact, high-performing TENG using a composite high-surface-area polyacrylonitrile (PAN) nanofiber with zeolitic imidazolate framework-8 (ZIF-8), a metal-organic framework (MOF) that exhibits structural discretion. The production of ZIF-8 was based on a solvothermal approach, utilizing zinc nitrate and 2-methylimidazole in methanol. The output of PAN nanofibers was achieved through the electrospinning process. A vertical contact- separation mode TENG was developed using the PAN@ZIF-8 composite as a tribo- positive layer and polyethylene terephthalate (PET & Teflon) as the tribo-negative layer. XRD, SEM, FTIR, Raman spectroscopy, UV-Vis, and IV were conducted to characterize the materials. The crystallinity of ZIF-8 was established through the XRD, whereas Raman and FTIR spectra ratified the Zn-N bonding and the integrity of the functional groups. UV-Visible analysis gave a broad optical bandgap of 5.04 eV. The TENG-fabricated device produced a periodically alternating current in response to mechanical stimulation, making it suitable for energy harvesting. The outcomes suggest the potential use of MOF-polymer composites in enhancing the triboelectric capabilities of the material and its applications in wearable electronic systems, self- powered sensors, and IoT devices.