Conveners
Physics of Condensed Matter and Materials
- Tebogo Mokhine (SAIP)
- Brian Masara (SAIP)
Physics of Condensed Matter and Materials
- There are no conveners in this block
Physics of Condensed Matter and Materials
- There are no conveners in this block
Physics of Condensed Matter and Materials
- There are no conveners in this block
Physics of Condensed Matter and Materials
- There are no conveners in this block
Physics of Condensed Matter and Materials
- There are no conveners in this block
Physics of Condensed Matter and Materials
- There are no conveners in this block
Structuring materials to exhibit phenomena such as negative refractive indices and near-zero indices has given rise to an exciting class of materials, known as metamaterials and their 2D counterparts, metasurfaces. Due to these unique properties and the ability to control the size, shape, density and orientations of these materials, one is able to have unprecedented control of their impact on...
The class of R2T2X intermetallics (R = rare earth, T = transition metal, X = main group) have a geometrically frustrated R-lattice which forms layers arranged in a Shastry-Sutherland lattice. In addition, due to the basic triangular motif in the frustrated structure, stabilization of different nearest-neighbor J values leads to complex low-temperature magnetic behavior. In this work, we have...
Multiferroic rare-earth composites in thin-film format have shown promising results towards the attainment of strong coupling of ferroic orders (ferroelasticity, ferromagnetism, ferroelectricity, and ferrotoroidicity) at room temperature, which is a key parameter to the realization of low-energy dissipating devices such as solid-state refrigerators, spintronic memory storage, etc. In this...
Impact of Helium (He) in the migration of strontium implanted 6H-SiC
T.F. Mokgadi$^1$, T.T. Hlatshwayo$^1$, M. Msimanga$^2$, V.A. Skuratov$^3$
$^1$ Physics Department, University of Pretoria, Pretoria, South Africa.
$^2$ Physics Department, Tshwane University of Technology, P Bag X680, Pretoria 0001, South Africa
$^3$ *Joint Institute for Nuclear...
Demands for higher performance of solar cells have led researchers to non-sophisticated, low temperature crystal-growth processes like spray pyrolysis and sol-gel spin coating as the future of efficient solar cells technology as stability remains challenge. This project seeks investigation of Beta-Gallium Trioxide (β-Ga2O3) for solar cells passivation to improve their stability and PCE,...
A series of undoped mixed phase BaAl2O4/CaAl4O7 (hereafter called BC) and doped BC:x% Eu3+ (0 < x ≤ 5.5) mixed phases nanophosphors were successfully prepared by the citrate sol-gel technique. The structure, morphology and optical properties of the nanophosphors were studied in details by the X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM)...
Heavy transition metals are frequently used as electrodes and substrates in scanning tunneling microscopy experiments. In the constricted low dimensional systems that occur in such experiments, typically under conditions of non-zero bias voltage, spin-imbalance may develop even in non-magnetic atomic- and nano-systems. This phenomenon arises as a result of spin selective effects mediated by...
In this study, the phase stability of B2 and B19 Ti50Pt43.75-xCoxTa6.25 structures using ab initio density functional theory approach was investigated. Their structural, vibrational and mechanical properties were determined to show their stability. The supercell approach was employed to substitute Pt with Ta on the TiPtCo and evaluate the stability of the structures. The calculated heats of...
The comparison study on adsorption of normal butyl xanthate (PNBX), mono butyl dithiocarbamate (BDTC) and dibutyl dithiophosphate (DBDTP) on sperrylite mineral forms a basis in understanding the floatability improvement and paves a way for design of collectors that may impact a wide range of arsenide minerals. This study used a computational density functional theory (DFT) and experimental...
Aluminium oxide (α-Al2O3) emerged as a potential surface coating material for Li-ion batteries because it has proved to improve the electrochemical performance and capacity upon cycling. It was also considered due to its high thermal conductivity, resistance against extreme temperatures and excellent electric insulation. Despite the intense studies on the surface coating...
One of the major limitations associated with spinel LiMn2O4 despite its superior properties such as high voltage, great cycling performance, being environmentally friendly and cost-effective is the impact of the stress it endures through strain during the process of cycling. For that reason, this study seeks to understand the implications that come with stress-strain and how it affects the...
Titanium can be produced as both a metal and in powder form. It finds applications in various industries such as in medical and aerospace, where the fabrication of components with excellent corrosion and high-temperature performance are significant. The titanium metal also plays a significant role in the titanium production process due to its desirable physical and chemical properties. Also,...
Ion beam induced sputtering in matter is of interest for fundamental ion-atom interaction studies. It is also important for practical applications such as ion beam materials analysis techniques like Secondary Ion Mass Spectrometry at MeV ion energies (MeV SIMS). Theoretical descriptions of nuclear sputtering yields due to keV projectile ions are generally in good agreement with experimental...
In this study, polyaniline thin films with thickness of approximately 100 nm were spin-coated on a silicon substrate. The films were then irradiated at normal incidence and room temperature by 150 keV Ar+ ions to fluences ranging from 1 × 10^12 to 5 × 10^16 ions/cm2. According to the Monte Carlo simulation code, Stopping and Range of Ions in Matter (SRIM), the approximate penetration depth of...
Ion Beam Analysis (IBA) is a suite of techniques used to determine elemental composition and depth profiles of thin film materials. Ion beam induced damage in soft insulating materials like polymers can be a limiting factor to the accuracy of IBA especially when using heavy ions. The usability of Heavy Ion Elastic Recoil Detection Analysis (ERDA) at iThemba LABS for analysis of polymeric...
Ion implantation is a technique of choice for inducing disorder in semiconducting materials such as crystalline GaAs. Interestingly, the properties of these amorphous materials such as the medium-range order (MRO) and small range order (SRO) depend heavily on the material of interest and its implantation conditions. Understanding the crystalline to amorphous phase transformations is vital for...
A suite of electronic and magnetic property studies were conducted on a Pr0.5La0.5Pt4Ge12 (Skutterudite) polycrystalline sample with an objective of investigating its superconducting state. The two parent compounds PrPt4Ge12 (Tc= 8K) and LaPt4Ge12 (Tc= 7.8K) both form in the filled-cage cubic Skutterudite structure and both have a superconducting ground state. However, their superconducting...
A polycrystalline sample with the nominal composition RhFe3C was synthesized and its properties were investigated using powder x-ray diffraction (XRD), transmission Mössbauer spectroscopy and heat capacity Cp(T) measurements. The XRD data shows that RhFe3C has a cubic structure with a lattice parameter of 5.8907(3) Å. The room temperature Mössbauer spectrum of RhFe3C exhibits magnetic...
The cathode materials that can exhibits a capacity of >270 mAh/g with little or no capacity fade are the most promising next-generation cathode active materials for Li-ion batteries. Hence, the layered oxides relative to the stoichiometry Li1+yMn1-yO2 can deliver discharge capacities of >250 mAh/g after they have been activated by charging first to a voltage of 4.6–4.9 V in a Li-cell. However,...
Due to the outstanding chemical stability against high voltage electrode, the oxide garnet with tetragonal structure Li7La3Zr2O12 (LLZO), is one of the most promising solid-state electrolytes for li-ion batteries. However, it has low ionic conductivity (~10-6 S.cm-1) at room temperature, which limits its practical application. Doping with a supervalent cation such as Ta on the Zr site of LLZO...
The demand for lithium-ion batteries has increased in the last decades due to their broad applicability as power storage systems. However, their energy density is too low for high-power applications such as electric vehicles and renewable energy storage grids. The most substantial electroactive component of a battery is the cathode and thus much research has been devoted to improving them. In...
The realisation of advanced lithium-ion battery (LIB) technologies has been hindered by the slow progress in discovering high capacity cathodes. Considerable research is focused on the lithium-rich layered Li2MnO3 owing to its ability to reversibly intercalate more lithium. However, the cycling of this material results in capacity degradation due to complex phenomena such as the irreversible...
Li-Mn-O layered-spinel composites are among the promising and economically viable, high energy density cathode materials for improving the performance of lithium ion batteries. A number of studies have focused on the specific capacity of these composite materials. However, the complex internal structural changes affecting their performance during the discharge process (lithiation) are not yet...
In this investigation, air plasma spraying was used to coat two sets of geometrically different Ti-6Al-4V alloy substrates with hydroxyapatite (HAp). The two sets of samples were then immersed in simulated body fluid (SBF), a fluid whose ionic composition resembles that of the human fluid, to determine the biofunctional performance of the coatings. Immersion was done for varying time periods...
Iron doped (FE:5Ti) sodium and (FE:10Ti) potassium titanates were prepared by the Pechini sol-gel method and calcined at 800 . X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectrometry (EDS), FTIR and Raman spectroscopy were used to characterize the titanate nanomaterials. A quantitative XRD analysis using...
Mixed phases of Tb3+ doped CaAl2O4/Ca1.02Sr1.98Al2O4/SrAl2O4/SrO/Al2O3 (CCSSA:x%Tb3+ (0 ≤ x ≤ 2)) nanophosphors were successfully prepared using sol-gel method. X-ray diffraction (XRD) patterns revealed that all the annealed samples resembled the mixed phases of monoclinic (CaAl2O4 and SrAl2O4), cubic (Ca1.02Sr1.98Al2O4 and SrO) and hexagonal (Al2O3) crystal structures, which were not...
Citrate sol-gel method was used to successfully prepare mixed phases of strontium and barium aluminate powders doped with 0.1% Tb3+. All powders were annealed at 1000 oC while varying the annealing time (AT) from 0.5 – 4 hours (h). The X-ray powder diffraction (XRD) results revealed that the prepared powders is the mixture of phases consisting of cubic (Sr3Al2O6, Ba3Al2H12O12), monoclinic...
High entropy alloys (HEA) containing Co, Ni, Fe have recently enjoyed considerable attention in the material sciences due to their interesting mechanical and magnetic properties that are further enhanced by the additive manufacturing technique often used to process them.
HEAs are theoretically difficult to describe as they often form amorphous structures and the Bloch theorem is not...
Perovskite-based solar cells (PSC) is the rapidly emerging solar technology up to the present since its introduction in 2009, hence invigorating the photovoltaic (PV) zone. To reach the maximum potential of hybrid perovskite solar cell performance, analyses of the dominant mechanisms in a perovskite material, together with interfacial properties of contact materials and their impact on the...
ERDA and RBS analysis of hydrogenated Pd-Ti-Pd multilayer stacked film prepared on CT-Ti and Ti6Al4V substrates using an electron beam evaporator were conducted in this investigation. The hydrogenation of the samples was achieved by flowing pure H2 (100%) and H2(15%)/Ar(85%) gas mixture while annealing samples at 550oC. The stability of the multilayer stack system at 550 °C was also...
In this study, 4H-silicon carbide samples were bombarded with 167 MeV Xe ions to a fluence of 1×108 cm-2 at 300 K prior to the fabrication of Schottky contacts. The samples were also annealed at approximately 900 °C before thermal fabrication of the contacts. When compared current-voltage results with the as-grown device, generation-recombination occurred in the implanted samples. The presence...
Limestone is a calcareous rock and is among the common hydrocarbon reservoirs (others being dolostone, sandstone and unconsolidated sands). Carbonate reservoirs hold a significant percentage of the world's oil and gas reserves. This study explores the nanopore structure of calcitic and dolomitic limestone by virtue of them being abundant in the chosen area of study. The difference between...
ZnO (wurtzite) samples were implanted with Ar+ ions to generate intrinsic defects within the samples for fluencies ranging from 10^4 to 10^18 per cm. Doppler broadening of the annihilation centroids were obtained to determine S- and W - parameters which are associated with a quantity of defects. X-ray diffraction (XRD) method was employed to determine any structural or phase change associated...
The global share of photovoltaic (PV) technologies in the electricity and energy production still remain marginal today and is likely to remain this way for a long period of time especially in the poor developing countries [1]. The evidence of the limited global impact of PV is marked by the increasing market share of fossil fuels in the generation of electricity [2]. Carbon nanotubes (CNT)...
Ti50Pd50 system is considered as one of the potential high temperature shape memory alloy (HTSMA) due to their high martensitic transformation temperature at 823 K. Previous studies showed that this alloy is unstable displaying a negative shear modulus (C′) at 0 K. In order to improve the properties, partial substitution of Pd with Cu are being investigated. The equilibrium lattice parameters,...
Minerals are exposed to oxidation due to weathering and aging which have significant effect on their floatation. Furthermore, the hydrophobicity and hydrophilicity of minerals are crucial in determining their wettability that can be useful in the floatation process design. In this study we investigate the structural, surface and electronic properties of the nickel-rich pentlandite (Fe4Ni5S8)...
Pentlandite is a major precious metals-bearing mineral and plays a very important role in mining. Precious metal ores co-exists with base metals either as solid-solution and intergrowths, hence rendering its detailed understanding important for efficient extraction of these precious metals. In order to extract the precious metals from the ores effectively it is necessary to study and...
Abstract
We explore the synthesis of mesoporous titanium dioxide (mp-TiO2) nanoparticles using cost effective method, sol-gel. mp-TiO2 films are existing electron transport layers in perovskite solar cells (PSCs) and the material development is encouraged for their commercialization . Different synthesis approaches give rise to different morphologies, mesostructures, pore size and...
Er-doped ZnO thin films (0, 2, 4 and 6 at.% Er) were prepared using the sol-gel spin coating technique. The morphology of the thin films was studied using scanning electron microscopy (SEM). The structure was investigated by X-ray diffraction (XRD). It was found that the films have hexagonal wurtzite structure with randomly orientated particles and the crystallite size decreased from 32 nm to...
Effects of helium (He) in the migration behaviour of silver (Ag) implanted into polycrystalline silicon carbide (SiC) were investigated. Sliver ions at 360 keV were implanted into SiC to a fluence of 2 × 1016 cm-2 at 350 oC. Some of the as-implanted samples were then implanted with helium (He) ions of 17 keV to a fluence of 1 × 1017 cm-2 at 350 oC. The Ag implanted and He & Ag co-implanted...
Lithium-air batteries, based on their high theoretical specific energy, are a particularly attractive technology for electrical energy storage that promises a long-range electric vehicle extensively affordable. However, they suffer from the production of unstable discharge products which leads to capacity fading of the battery. Several catalysts have been used to improve Oxygen Reduction...
The physio-chemical properties of semiconducting diamond materials under extremely low temperatures have fundamental implications in Condensed Matter Physics. Highly doped boron diamonds have been shown to reach a superconductive state at critical temperatures ($T_c$) ranging from $4-10$K, albeit, such properties are "at the moment" only attributed to heavily boron-doped synthesized samples...
Sodium oxides with mixed transition metals have received significant attention as positive electrode candidates for sodium-ion batteries, due to their high reversible capacity. To understand the relation between layered structures and electrochemical properties, it is necessary to understand layered compound phase transformations during electrochemical responses. Using first-principles...
Magnetite (Fe3O4) has drawn interest since its discovery since it is one of the naturally occurring minerals that has importance in paleomagnetic measurements used to study continental drift [1]. The compound is also found in the mantle wedge of subduction zones [1]. Magnetically, Fe3O4 orders ferrimagnetically with a Curie temperature of 850 K having an inverse spinel structure, AB2O4, with...
We have used conventional deep-level transient spectroscopy (DLTS) and high resolution Laplace deep level transient spectroscopy (L-DLTS) to investigate electron-irradiation induced defects in phosphorous doped (n-type) silicon implanted additionally with arsenic, antimony and both arsenic and antimony. All samples exhibited similar DLTS spectra, with peaks at 219 K, 166 K, 128 K, and 92 K....
Vanadium pentoxide (V2O5) is a semiconductor metal oxide material with properties that makes it suitable for gas sensing applications. These properties are strong catalytic activity, high conductivity and structural ability. Despite this, literature showed that low selectivity and high operating temperatures still limit its functionality in practice. Sulphur dioxide (SO2) is a highly toxic...
In this study, the plasmonic effect of gold nanoparticles (AuNPs) inside poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) for improving light scattering of organic solar cells have been investigated. Chloroauric acid is capped with trisodium citrate in which the solution is heated to obtain Au NPs. Au NPs are deposited in PEDOT:PSS and spin coated on top of glass substrate...
The influence of duration of annealing on thermoluminescence of natural quartz annealed at 1000 °C is reported. The study looks at samples annealed for 10 and 60 minutes. A glow curve measured at 1 °Cs-1 after beta irradiation to 50 Gy for the sample annealed for 10 minutes shows seven peaks at 68, 130, 176, 276, 300, 360, and 416 °C labelled I through VII. The sample annealed for 1 hour has...
KM Monareng1, RR Maphanga2,3 and SP Ntoahae1
1Department of Physics, University of Limpopo, Private bag x 1106, Sovenga, 0727
2Next Generation Enterprises and Institutions, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria, 0001
3National Institute of Theoretical Physics, NITheP, Gauteng
Abstract
Machine learning methods have recently found applications in many...
R-T-X (R= rare-earth, T= Transition element and X = p-block element) ternary intermetallic compounds have drawn considerable attention for their diversity of structural, electronic, and magnetic properties. R3T4X12 type of compounds are of particular interest among intermetallics because the crystal structure contains layers as well as triangular and distorted Kagomé lattice features. In this...
CoSe and Zr doped CoSe thin film materials were successfully synthesized via spray pyrolysis technique. The optical, structural and electrical characterization where carried out using UV –visible spectrophotometer, XRD and four point probe at ambient temperature. The materials showed good optical, structural and electrical properties. The energy band gap of the of the material pepared at...
ABSTRACT
The III-Nitride semiconductor materials are wide bandgap materials and can be crystalline as the structure of wurtzite and zinc-blende types. Wurtzite InN, GaN and AlN have direct bandgap 1.9 eV, 3.4 eV and 6.2 eV, respectively [1]. GaN is an extremely promising material for the blue and white light-emitting diodes LEDs, leaser and detectors [2].
İn this study GaN thin films were...
In this study, sequential physical vapor deposition (SPVD) technique is used to grow high poly-crystalline yellow active orthorhombic γ-CsPbI3 structure with Pnma space group. Crystallographic parameters and the phase transition from as-deposited orthorhombic (γ-CsPbI3) to tetragonal (β-CsPbI3) on annealing at 100 °C are determined using Rietveld refined X-ray diffraction (XRD) patterns....
CaAl2O4:0.1%Tb3+, x% Sm3+ (0<x<2) nano-powders have been successfully prepared via sol-gel technique. Annealing temperature and time were kept constant at 900 oC and 2 hours (h), respectively for all samples. X-ray diffraction (XRD) analysis showed that all powder samples have a monoclinic structure without any impurities. Energy dispersive X-ray spectroscopy (EDS) results confirmed the...
Using Raman spectroscopy and Secondary ion mass spectrometry (SIMS), the effects of implantation temperature and annealing have been investigated for glassy carbon (GC) samples implanted with Se ions. 150 keV Se ions were implanted into GC separately at RT, 100 °C, 150 °C, and 200 °C to a fluence of 1.0 × 10^(16) ions/cm^(2). The as-implanted samples were subjected to annealing from 1000 °C up...
Light emitting un-doped mixed phase BaAl2O4/CaAl4O7 (here after named BC) and BC: x% Dy3+ (0 < x ≤ 3) nanophosphors were prepared using citrate sol-gel method. Their morphology and photoluminescence (PL) properties were studied by X-ray Diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM) and Commission international de l’éclairage (CIE). XRD and SEM...
