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Abstract: The exchange bias blocking temperature distribution of naturally oxidized Co-CoO core-shell nanoparticles exhibits two distinct signatures. These are associated with the existence of two magnetic entities which are responsible for the temperature dependence of an exchange bias field. One is from the CoO grains which undergo thermally activated magnetization reversal. The other is from the disordered spins at the Co-CoO interface which exhibits spin-glass-like behavior. We investigated the oxide shell thickness dependence of the exchange bias effect. For particles with a 3 nm thick CoO shell, the predominant contribution to the temperature dependence of exchange bias is the interfacial spin-glass layer. On increasing the shell thickness to 4 nm, the contribution from the spin-glass layer decreases, while upholding the antiferromagnetic grain contribution. For samples with a 4 nm CoO shell, the exchange bias training was minimal. On the other hand, 3 nm samples exhibited both the training effect and a peak in coercivity at an intermediate set temperature Ta. This is explained using a magnetic core-shell model including disordered spins at the interface.
Keywords: exchange interactions, magnetic ordering, ferromagnetic materials, magnetic materials, polycrystalline material, thin films, nanoparticle, nuclear structure models, oxides, transition metals
Published in RUNG: 13.12.2024; Views: 77; Downloads: 0
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Abstract: The contamination of water bodies by microorganisms is seen as a highly significant issue that poses a threat to human and animal well-being. The primary objective of this master thesis is to develop and evaluate an environmentally friendly photoelectrochemical (PEC) method using porous Fe₂O₃ thin films for the disinfection of wastewater. This thesis presents the novel application of porous Fe₂O₃ thin films, which were produced using a cost-effective spin-coating technique, to improve the process of PEC disinfection. The PEC approach has been demonstrated to be highly effective in disinfection of wastewaters deliberately contaminated with E. coli bacteria. The crystallinity of the Fe₂O₃ porous thin films was confirmed using X-ray diffraction (XRD), while the film morphology was studied using scanning electron microscopy (SEM). The PEC disinfection procedures were conducted in the presence of two separate electrolytes, sodium sulfite (Na₂SO₃) and sodium chloride (NaCl), which were chosen for their specific roles in improving the effectiveness of disinfection. The PEC method shown efficacy in inactivating E. coli, with 45% of the bacteria being inactivated in the presence of 2 mM Na₂SO₃ and complete inactivation achieved with 20 mM NaCl. The findings suggest that the PEC disinfection process is a highly efficient and eco-friendly technology that can be used as a practical substitute for traditional disinfection methods. As a result, it has potential applications in ensuring public safety and safeguarding the environment, particularly in relation to wastewater treatment.
Keywords: Treated wastewater, Disinfection, Escherichia coli, Photoelectrochemical oxidation, Fe2O3 thin films, Sodium sulfite and Sodium chloride.
Published in RUNG: 09.09.2024; Views: 840; Downloads: 14
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Keywords: iron, Chelex resin, diffusive gradients, thin films, beam deflection spectrometry
Published in RUNG: 09.01.2024; Views: 1427; Downloads: 3
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Keywords: carbides, boron carbide, thin films, corrosion resistance, electronics, natural carbon
Published in RUNG: 25.04.2023; Views: 1965; Downloads: 7
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Keywords: metal-organic framework, 2D materials, salicylaldehyde, thin films, mechanochemistry
Published in RUNG: 10.02.2023; Views: 2011; Downloads: 3
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