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- ItemEnergy gap measurements based on enhanced absorption coefficient calculation from transmittance and reflectance raw data(Elsevier, 2024-01-18) Allaham, Mohammad Mahmoud; Dallaev, Rashid; Burda, Daniel; Sobola, Dinara; Nebojsa, Alois; Knápek, Alexandr; Mousa, Marwan; Kolařík, VladimírThe absorption coefficient plays an important role in studying and characterizing semiconducting materials. It is an important parameter to study the mechanism of photons absorption within the structure of the studied material. Thus, it helps to study the several types of charge carrier transport along with the energy band structure and its defects. In literature, a formula was reported to precisely calculate the absorption coefficient from raw data of transmittance and reflectance of electromagnetic radiation. However, the reported formula has several issues limiting its validity in the literature. In this paper, we provide a more mathematically accurate form of this equation to precisely obtain the absorption coefficient from the raw data, by considering the total internal reflection at the different interfaces. Moreover, the equation is tested by simulated data and is applied to study the optical characteristics of a single-component epoxy resin from its transmittance and reflectance raw data.
- ItemModeling of Magnetic Films: A Scientific Perspective(MDPI, 2024-03-21) Misiurev, Denis; Holcman, VladimírMagnetic thin-film modeling stands as a dynamic nexus of scientific inquiry and technological advancement, poised at the vanguard of materials science exploration. Leveraging a diverse suite of computational methodologies, including Monte Carlo simulations and molecular dynamics, researchers meticulously dissect the intricate interplay governing magnetism and thin-film growth across heterogeneous substrates. Recent strides, notably in multiscale modeling and machine learning paradigms, have engendered a paradigm shift in predictive capabilities, facilitating a nuanced understanding of thin-film dynamics spanning disparate spatiotemporal regimes. This interdisciplinary synergy, complemented by avantgarde experimental modalities such as in situ microscopy, promises a tapestry of transformative advancements in magnetic materials with far-reaching implications across multifaceted domains including magnetic data storage, spintronics, and magnetic sensing technologies. The confluence of computational modeling and experimental validation heralds a new era of scientific rigor, affording unparalleled insights into the real-time dynamics of magnetic films and bolstering the fidelity of predictive models. As researchers chart an ambitiously uncharted trajectory, the burgeoning realm of magnetic thin-film modeling burgeons with promise, poised to unlock novel paradigms in materials science and engineering. Through this intricate nexus of theoretical elucidation and empirical validation, magnetic thin-film modeling heralds a future replete with innovation, catalyzing a renaissance in technological possibilities across diverse industrial landscapes.
- ItemCharacterization of high entropy ceramic powders: band gap evolution with temperature of calcination(MDPI, 2024-03-22) Dallaev, Rashid; Spusta, Tomáš; Allaham, Mohammad Mahmoud; Spotz, Zdeněk; Sobola, DinaraThis manuscript presents a comprehensive exploration of the band gap structure in (CoCrFeNiMn)3O4 powders through a series of experimental investigations. The combined use of optical techniques, and X-ray photoelectron spectroscopy in this study offers a comprehensive characterization of the band gap structure in (CoCrFeNiMn)3O4 powders. The findings contribute to the understanding of the material's electronic properties and pave the way for potential applications in electronic and optical devices.
- ItemCombination NIPS/TIPS Synthesis of -Fe2O3 and /-Fe2O3 Doped PVDF Composite for Efficient Piezocatalytic Degradation of Rhodamine B(MDPI, 2023-10-02) Magomedova, Asiyat; Rabadanova, Alina; Shuaibov, Abdulatip; Selimov, Daud; Sobola, Dinara; Rabadanov, Kamil; Giraev, Kamal M.; Orudzhev, FaridHighly porous membranes based on polyvinylidene fluoride (PVDF) with the addition of nanoscale particles of non-magnetic and magnetic iron oxides were synthesized using a combined method of non-solvent induced phase separation (NIPS) and thermo-induced phase separation (TIPS) based on the technique developed by Dr. Blade. The obtained membranes were characterized using SEM, EDS, XRD, IR, diffuse reflectance spectroscopy, and fluorescent microscopy. It was shown that the membranes possessed a high fraction of electroactive phase, which increased up to a maximum of 96% with the addition of 2 wt% of alpha-Fe2O3 and alpha/gamma-Fe2O3 nanoparticles. It was demonstrated that doping PVDF with nanoparticles contributed to the reduction of pore size in the membrane. All membranes exhibited piezocatalytic activity in the degradation of Rhodamine B. The degree of degradation increased from 69% when using pure PVDF membrane to 90% when using the composite membrane. The nature of the additive did not affect the piezocatalytic activity. It was determined that the main reactive species responsible for the degradation of Rhodamine B were (OH)-O-center dot and O-center dot(2)-. It was also shown that under piezocatalytic conditions, composite membranes generated a piezopotential of approximately 2.5 V.
- ItemAnalysis of processing efficiency, surface, and bulk chemistry, and nanomechanical properties of the Monel® alloy 400 after ultrashort pulsed laser ablation(IOP Publishing Ltd, 2024-01-01) Ronoh, Kipkurui; Novotný, Jan; Mrňa, Libor; Knápek, Alexandr; Sobola, DinaraMonel (R) alloy 400 has excellent corrosion resistance and finds applications in marine industries. The processing of marine components requires high processing efficiency and a quality finish. Hence, this research aims to investigate the effects of the laser processing parameters such as laser fluence, scanning velocity, hatching distance, and the scanning pass on the ablation rates and efficiency, chemistry, and nanomechanical properties of the Monel (R) alloy 400 after pulsed picosecond (ps) laser ablation. From the experimental findings, the ablation depth increases as the laser fluence increases while decreasing as the scanning velocity increases. Surface roughness was noted to increase as the laser fluence increased. The findings demonstrated that the ablation rate increases as laser fluence increases while ablation efficiency decreases. Energy dispersive x-ray spectroscopy (EDX) showed that the elemental composition of laser-ablated zones is almost similar to that of the polished sample. X-ray spectroscopy (XPS) shows that the outer layer on the surface of Monel (R) alloy 400 is composed of NiO and CuO. The hardness and Young's modulus of the laser-processed alloy were found to be less than those of the bulk material. This study can be used to establish optimal processing parameters for the ultrafast ps laser processing of materials to achieve high ablation efficiency with a high-quality surface finish for industrial applications.