School of Science

Functionalized multiwall carbon nanotubes for electronic and magnetic applications

Thu, 12 Nov 2020 00:00:00 GMT

Functionalized multiwall carbon nanotubes for electronic and magnetic applications Oke, James Ayodele In this work, SiO2, MWCNTs, MWCNTs:SiO2, MWCNTs-TiO2, and MWCNTs:TiO2:SiO2 nanomaterials were synthesized and characterized by the use of different techniques to ascertain novelty of the nanomaterials and also to establish their suitability for several electrical, electronic and magnetic based device applications. The results, in general, indicate that the nanocomposites were well prepared and the properties of MWCNTs can be tuned by introducing SiO2, TiO2, and a composite of SiO2 and TiO2 in its matrix. This tunability of properties leading to the suitability of the material for various applications has been explained in this work

Measurement of Heavy Ion induced X-ray production cross sections in metallic targets at MeV energies

Sat, 20 Apr 2019 00:00:00 GMT

Measurement of Heavy Ion induced X-ray production cross sections in metallic targets at MeV energies Masekane, Masedi Carington Experimental X-ray production cross sections (i.e. probability of X-ray generation in a target by an incoming MeV ion) are useful not only for fundamental ion beam – matter interaction studies, but also for the development of new ion beam materials analysis techniques such as Heavy Ion Particle Induced X-ray Emission (HI-PIXE) spectroscopy. Unfortunately, while theoretical predictions of X-ray production cross sections due to light (Z<6) projectile ions are generally in good agreement with experiment, this is not the same for heavier projectiles. Experimental studies show that heavy ions induce higher X-ray yields in targets compared to light ions of the same velocity, which implies higher sensitivity for Heavy Ion PIXE. There is therefore a need for substantial experimental data to improve theoretical models. This dissertation presents measurements carried out at the iThemba Laboratory for Accelerator Based Sciences (LABS) to determine X-ray production cross sections in Vanadium (V), Zirconium (Zr) and Tin (Sn) metal oxide films due to carbon and chlorine MeV ion beams at an ion velocity range of 0.1-1.0 MeV/u. The measured cross sections are compared to predictions by the modified Plane Wave Born Approximation (PWBA) and the ECPSSR theory that takes into account; the energy loss (E) of the projectile due to Coulomb deflection (C) by the target atom, and the perturbed-stationary state (PSS) and relativistic nature (R) of the target atoms’ inner shell. The observed agreements and discrepancies between experiment and theory are discussed in terms of the atomic ionization mechanisms for each projectile-target collision

Exploring the use of visual aids in teaching grade 7 geometry to enhance the learning experience

Thu, 23 Apr 2026 00:00:00 GMT

Exploring the use of visual aids in teaching grade 7 geometry to enhance the learning experience Rivone, Sookraj This study addresses the use of visual aids in teaching geometry to enhance learners’ learning experience. This qualitative phenomenological study draws from Duval’s theory of semiotic representation which emphasises the alignment of symbolic, iconic and indexical representations in the connection of abstract mathematical concepts with practical and concrete learning experiences. Through purposive sampling, six teachers teaching Grade 7 mathematics were sampled and engaged in semi-structured interviews. Classroom observations were conducted to explore the teachers’ interaction with learners in their respective classrooms. This study shows that using semiotic representations in geometry supports learners’ interest and engagement, which in turn improves their understanding. This explains that the use of visual aids in teaching geometry impacts on the semiotic registers, that is, the visual, symbolic and verbal registers to enhance geometric cognitive understanding and knowledge retention. In addition, the findings show that visual aids help make abstract concepts tangible and support the development of deductive reasoning as a skill necessary for geometric problem-solving. The current study emphasise that the effective use of visual aids requires educators to align visual aids with curriculum goals, apply multi-representational strategies and differentiate instruction. Visual aids also promote equity by improving learners’ access to learning. Essentially, using visual aids to teach geometry leads to inclusive, and mind-emancipating experiences with far-reaching implications for pedagogy and education equity. In this study, recommendations emphasise practical and collaborative ways to improve the teaching of geometry using visual aids in South Africa, especially in under-resourced schools. Educators should use creative, low-cost materials and adapt visual aids to meet different learner needs in extreme cases where there is lack of resources. Schools should develop shared resource systems and build partnerships to access basic teaching tools. Thus, a combined effort by schools, education authorities, communities and the private sector is needed to improve resource access, promote equity towards effective teaching and meaningful learning in mathematics classrooms.

Electronic, electrical and magnetic properties of graphene oxide functionalized with gold and iron nanoparticles

Fri, 01 Jan 2021 00:00:00 GMT

Electronic, electrical and magnetic properties of graphene oxide functionalized with gold and iron nanoparticles Idisi, David Omoefe In the current project, GO was synthesized and functionalized with gold and iron oxide nanoparticles. Several characterization techniques were performed to study the change in the microstructural, electronic, electrical and magnetic properties of rGO due to functionalization. The obtained results from the study showed weak ferromagnetic and superparamagnetic features for rGO:Au-NP and supermagnetism for rGO-ATAFe 2O3 nanocomposites. The source of the observed magnetic features were mainly attributed to defects induced into rGO by oxygen moieties, Au and Fe atoms bonding on the edge and basal planes of GO. The charge storage behavior and magnetic properties of rGO:Au-NP composite indicate that the material can be useful for applications in ferro-electric and memory devices. The rGO:Fe2O3 nanocomposite can find potential in magnetic resonance imaging contrast agent application due to the observed superparamagnetic properties.