Comparative of Flammable and Toxic Gas Sensing behavior for Rare-Earth Elements Substituted Cobalt based Spinel Ferrites
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Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
University of Zululand
Abstract
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.
Description
A thesis submitted to the Faculty of Science, Agriculture and Engineering in fulfilment of the requirements for the Degree of Master of Science in the Department of Physics at the University of Zululand, South Africa, 2021.
Keywords
Flammable and Toxic Gas, Rare-Earth elements, spinel ferrites