Applied Physics Conference Papers
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- ItemEffect of Mo content on the structural and physical properties of Cr100-xMox alloys(South African Institute of Physics, 2014) Chavan, A.U.; Prinsloo, A.R.E.; Sheppard, C.J; Muchono, BlessedAlloying Cr with Mo, which is isoelectric with it, shows an unexpected decrease in the Néel temperature (TN) with an increase in Mo concentration. This is attributed to a delocalization of the 3-d bands in Cr through the introduction of 4-d electrons of Mo. In the present investigation the effect of Mo concentration on the structural, magnetic and electrical properties of Cr is systematically studied. A series of Cr100-xMox alloys, with x = 0, 3, 7, 15 and 25, was prepared and the actual concentrations established using electron microprobe analyses. XRD studies confirm the bcc structure of these alloys as in pure Cr and indicate an increase in lattice constant with an increase in Mo concentration. The crystallite sizes calculated from these results for the Cr100-xMox alloys ranges between 15 and 30 nm. The physical properties of these alloys were investigated through magnetic susceptibility (χ), Seebeck coefficient (S), electrical resistivity (ρ) and Hall coefficient (RH) as function of temperature (T) measurements. TN values obtained from these measurements are comparable.
- ItemEP-1308 IAEA support to national audit networks for radiotherapy dosimetry.(International Atomic Energy Agency (IAEA), 2013-04) Azangwe, GodfreyThe IAEA has along-standing history providing support and assistance for radiotherapy dosimetry audits in various countries. It has supported the development of methodology and establishment of several national TLD-based QA audit networks for radiotherapy dosimetry. The main objective was to extend the availability of radiotherapy dosimetry audits to as many radiotherapy centres as possible throughout the world. The overall radiotherapy dosimetry audit approach established and developed throughout these CRPs is based on a process of increasingly complex steps and parameters being checked. The first CRP focused on the basic beam calibration audits. The basic programme was extended to audits in non-reference conditions through a second CRP.
- ItemMagnetic behaviour of the Cr-Al alloy system around the triple point(South African Institute of Physics, 2011) Sheppard, C.J; Prinsloo, A.R.E.; Alberts, H.L.; Strydom, A.M.; Muchono, BlessedElectrical resistivity and specific heat measurements on a series of Cr1-xAlx (0 ≤ x ≤ 0.034) alloy single crystals are reported. The results indicate that the triple point, where the incommensurate and commensurate spin-density-wave phases coexist with the paramagnetic phase, is situated close to T = 0 K on the magnetic phase diagram.
- ItemMagnetic properties of the (Cr -xAlx) V alloy system(South African Institute of Physics, 2013) Muchono, Blessed; Sheppard, C.J; Prinsloo, A.R.E.; Alberts, H.L.Electrical resistivity (), Seebeck coefficient (S) and magnetic susceptibility () measurements as a function of temperature on the (Cr -xAlx) V alloy system, with 0 < x are reported. Néel temperatures (TN) obtained from all these measurements decrease with Al concentration, disappearing near x 1.5, again reappearing for x . (T) and S(T) for samples with x 6.1 show weak anomalies making the determination of TN difficult. However, these anomalies are sharply defined in (T), proving that it is an important tool in probing antiferromagnetic in this system. The present results show that the addition of just 1 at.% V to the Cr -xAlx alloy system suppresses antiferromagnetism in the concentration range 5 ≤ x ≤ . This behaviour is similar to that observed for the (Cr -xAlx) 5Mo5 alloy system.
- ItemMagnetic susceptibility studies of the (Cr98.4Al1.6)100-x Mox alloy System(South African Institute of Physics, 2014) Muchono, Blessed; Sheppard, C.J; Prinsloo, A.R.E.; Alberts, H.L.The magnetic susceptibility as a function of temperature, 𝜒𝜒(𝑇𝑇), on a spin-densitywave antiferromagnetic (Cr98.4Al1.6)100-xMox alloy system in the concentration range 0 ≤ x ≤ 8.8 is reported in order to investigate the possibility of quantum critical behaviour in this alloy system. Néel temperatures, TN, obtained from 𝜒𝜒(𝑇𝑇) measurements decrease with Mo concentration and sharply tend towards 0 K at a critical concentration xc ≈ 4.5. Antiferromagnetism is suppressed to below 4 K in alloys with x ≳ 4.5. Alloys in the concentration range 0 ≤ x ≤ 3.0 depict an upturn in the 𝜒𝜒(𝑇𝑇) curves just above the Néel temperature. The upturn is attributed to local magnetic moments formed around the impurity atoms. The magnetic phase diagram of the alloy system points towards the existence of a quantum critical point at the critical concentration x = xc. The suggestion of quantum critical behaviour in this alloy system from previous electrical resistivity(𝜌𝜌), Seebeck coefficient (𝑆𝑆) and specific heat (𝐶𝐶p) measurements is corroborated in this study.
- ItemOpen Source 3-D Printers: An Appropriate Technology for Building Low Cost Optics Labs for the Developing Communities .(Society of Photo-optical Instrumentation Engineers, 2017-08-16) Gwamuri, J.; Pearce, Joshua M.The recent introduction of RepRap (self-replicating rapid prototyper) 3-D printers and the resultant open source technological improvements have resulted in affordable 3-D printing, enabling low-cost distributed manufacturing for individuals. This development and others such as the rise of open source-appropriate technology (OSAT) and solar powered 3-D printing are moving 3-D printing from an industry based technology to one that could be used in the developing world for sustainable development. In this paper, we explore some specific technological improvements and how distributed manufacturing with open-source 3-D printing can be used to provide open-source 3-D printable optics components for developing world communities through the ability to print less expensive and customized products. This paper presents an open-source low cost optical equipment library which enables relatively easily adapted customizable designs with the potential of changing the way optics is taught in resource constraint communities. The study shows that this method of scientific hardware development has a potential to enables a much broader audience to participate in optical experimentation both as research and teaching platforms. Conclusions on the technical viability of 3-D printing to assist in development and recommendations on how developing communities can fully exploit this technology to improve the learning of optics through hands-on methods have been outlined.
- ItemOptics education in a developing country.(Society of Photo-optical Instrumentation Engineers, 2005-10-24) Jonathan, Enock.An optics laboratory plays a critical role in optics education. A major challenge for optics educators in Africa is the shortage or non-availability of laboratory teaching equipment. Optics teaching equipment is beyond the budget of most universities in the developing world such as the new National University of Science and Technology in Zimbabwe. The paper details a successful strategy - local fabrication/assembling of optics laboratory teaching aids - adopted by the Applied Physics Department at Zimbabwe's National University of Science and Technology. Students and technical staff under the guidance of an academic member of staff do equipment fabrication and assembling. The paper describes some of the project-type set-ups for performing experiments on (1) laser light scattering and impurity determination; (2) industrial imaging inspection (3) light transmission and reflection and (4) refractive index measurement
- ItemSpin-density-wave behaviour of the (Cr100-xAlx)95Mo5 alloy system(SAIP, 2011) Muchono, Blessed; Prinsloo, A.R.E.; Sheppard, C.J; Alberts, H.L.; Strydom, A.M.Electrical resistivity, Seebeck coefficient and specific heat measurements on a (Cr100-xAlx)95Mo5, 0 8.1 at.% Al alloy system are reported. The results indicate two possible quantum critical points in the magnetic phase diagram of this system. One is an incommensurate spin-density-wave – paramagnetic quantum critical point situated at 1.5 at.% Al and the other a paramagnetic – commensurate spin-density-wave critical point at 5 at.% Al. We forward experimental evidence that this system harbours two spin-density-wave related quantum critical points which presents an unusually rich case study for magnetic quantum criticality of the itinerant kind.