Browsing by Author "Shozi, Euphemia Nolwazi Nontobeko"

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    Comparative of Flammable and Toxic Gas Sensing behavior for Rare-Earth Elements Substituted Cobalt based Spinel Ferrites
    (University of Zululand, 2021) Shozi, Euphemia Nolwazi Nontobeko
    There is a considerable need to design and develop a Liquid petroleum gas sensor due to its use in households and high flammability to protect human safety. Therefore, in this research work, we present a variety of cobalt-based spinel ferrites doped with 4f electron rare-earth ions to be used as flammable gas sensors. These spinel ferrites were fabricated following a glycol hydrothermal chemical-process. Due to their electronic configuration and charge dynamics, they are very sensitive and selective to integrative liquefied petroleum gases (LPG). A high response of over 730 was recorded towards 1 vol% (or 10 000 ppm) of LPG at 225 °C. The CoSm0.1Fe1.9O4 nano-ferrite meets the criteria of a potential sensor of being highly sensitive and selective with repeatability and stability that maintained a high response of 241 over 63 days. The rare-earth elements doped cobalt based ferrites were classified according to two categories in terms of overall performance. The first category were the ferrites doped with the low 4f electrons and the second category belonged to the high 4f electrons. The first category composed of solid and compact nanoparticles and proved to be better in the LPG performance while giving low photoluminescence emission intensities. This latter category had the highest combined percentages of oxygen vacancies and adsorbed oxygen. A temperature dependent tunable carrier-type transition was observed. The ferrite has p-type characteristics at 225 °C and above, otherwise n-type below this operating temperature to room temperature.