Conveners
Physics of Condensed Matter and Materials
- Rudolph Erasmus (University of the Witwatersrand)
Physics of Condensed Matter and Materials
- Cliffton Masedi (University of Limpopo)
Physics of Condensed Matter and Materials
- Daniel Wamwangi (School of Physics, Materials Physics Research Institute, University of the Witwatersrand)
Physics of Condensed Matter and Materials
- Ramogohlo Diale (UL)
Physics of Condensed Matter and Materials
- BHARATI BAMANA (UNIVERSITY OF JOHANNESBURG)
Physics of Condensed Matter and Materials
- Rudolph Erasmus (University of the Witwatersrand)
Physics of Condensed Matter and Materials
- Thulani Jili (University of Zululand)
The ternary intermetallic compound $\rm{Ce_2Rh_2Ga}$ exhibits an unusual crystal structure transformation at 128.5 K [1] together with temperature-driven intermediate valence of the nominally trivalent cerium ions below room temperature [2]. Although the two phenomena may have a causal relationship, the origin of the structure transformation remains to be understood. Strongly correlated cerium...
NbC cermets with Fe and Ni binders have been vacuum sintered with molybdenum carbide additives for improved high temperature tribological applications. The magnetic, electrical and thermal properties are being investigated using Mӧssbauer spectroscopy and the Physical Property measurement system (PPMS). The addition of 4wt% molybdenum carbide to the Fe and Ni binder grades shows an average...
Organic solar cell (OSC) research has advanced significantly during the past few years with the introduction of new polymers. The molecular engineering of terpolymers has enabled easy morphological control in binary devices over ternary blends and power conversion efficiencies (PCEs) exceeding 18% have been recorded. However, in contrast to photovoltaics based on inorganic semiconductors such...
Boron Nitride (BN) nanotubes were grown on Silicon (Si) substrates using chemical vapor deposition at temperatures ranging from 900 to 1100 °C. Ion implantations were carried out with boron (B+) ions at energies of 150 keV and fluences of 1x10^14 and 5 x10^14ions/cm^2. Raman analysis revealed a peak at 1367/cm, which is an indication of the sp^2 hybridized BN planar bonding attributed to the...
This work focuses on development of mesoporous 1-D belt-like In2O3 nanostructures derived from a single-step electrospinning method as an effective approach to produce active sensing layers based on In2O3 with high active surfaces to make full use of the sensing activity of all nanostructures. The annealing temperature effect on methane sensing behavior of these belt-like In2O3 nanostructures...
Intrinsically Conducting Polymers (ICPs) hold promise for future electronics due to their low cost, light weight and easy processability. Among them, Polyaniline (PANI) is the most widely studied because it is environmentally stable and possesses interesting redox properties which gives it a high level of tunability in electronic structure. However, since PANI can exist in a multiplicity of...
Li2MnO3 has received great attention as potential cathode material due to its higher capacity, low cost and non-toxicity. However, its application is obstructed by its poor rate performance and structural degradation during cycling. Cationic dopants have been used to reduce the collapse of the structure and they tend to improve the performance of cathode materials. As...
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 for Theoretical and Computational Sciences, NITheCS, Gauteng, 2000
Abstract
Machine learning methods have recently...
Keywords: First-principles calculations, Density functional theory (DFT), Elastic properties, Phase stability, Density of states, Phonon dispersion and Shape memory
Abstract: Most Ti-based CsCl-type (Pm3m) compounds solidifies congruently to an ordered B2 phase of high symmetry at high temperature and transforms martensitically to lower symmetry phases upon cooling to room...
Abstract: FeCo alloy plays an important role in soft magnetic materials with a wide range of technological applications due to its high saturation magnetization and Curie temperature. However, this alloy shows low levels of ductility at room temperature. The ductility of this alloy can be improved by the ternary addition of Manganese (Mn). In this study, a supercell approach was used to...
Magnesium-ion batteries are facing major setbacks when it comes to the identification of cathode materials which will demonstrate capacities and voltages identical to lithium-ion systems. Then, in this study, we make use of first-principle based calculations to study the stability of the discharge products MgSc2S4, MgSc2Se4, MgY2S4, MgY2Se4, MgIn2S4, and MgIn2Se4 whereby we investigate their...
The development of permanent magnets without rare-earth elements has gained a lot of attension. The T-phase MnAl alloy has gained particular attention due to the low cost of materials required. The density functional theory (DFT) within the generalized gradient approximation (GGA) was used to perform first-principle calculations, to study the T-MnAl alloy. The effects of carbon and boron on...
Defects investigations were carried out in wurzite ZnO of space group P6_3mc, which were generated by 150 keV Ar+ ions during the implantation with fluencies from 10^4 to 10^16 cm-2. RBS technique was used to determine which elements are in the sample after implantation and X-ray diffraction was utilized to determine the presence of phase change or structural damage or both that might have...
Rare-earth based chromium oxides have attracted substantial research attention over the years because their unusual properties, such as magnetocaloric effect (MCE) [1-5]. An interesting member of these materials is $R$CrO$_4$, belonging to a family of $AB$O$_4$-type oxides, where $A$ is a rare-earth and $B$ = P, As, Cr, V. $R$CrO$_4$ compounds crystalize in zircon or monazite-type structure...
Organic plant-based dye for Dye-sensitized solar cells (DSSCs) have gained a great interest due to their low cost of manufacturing and environmental friendliness. Majority of
plants in nature contain pigments such as chlorophyll, anthocyanin and betalain that can be used in DSSCs. In this study, the solvents used to extract dye from B. pilosa leaves
as a sensitizer for DSSC were water,...
Copper nanowires (CuNWs) are a promising material for flexible transparent conductive electrodes due to their outstanding transparency and conductivity properties. Long and smooth CuNWs were successfully synthesized via a hydrothermal method and partially cleaned by n-hexane and water separation routine. The synthesized CuNWs were then deposited on a polycarbonate substrate to make a flexible...
Food is among the most traded commodities in the world. As markets grow and mass productions increase, there are concerns of safety during production, distribution, and storage. Highly sensitive and selective semiconducting metal oxide-based gas sensors have shown promising potential in detecting spoilage indicators at every stage of production to curb the risk of food wastage and poisoning....
This study involved rapid thermal annealing of Ag/ITO bilayer films of different Ag layer thicknesses in nitrogen gas at a typical kesterite precursor crystallization temperature. AFM analysis showed a thermally stable surface with fewer high peaks/valleys for the annealed thinner Ag layer bilayer films with relatively normally distributed homogeneous grains. Annealing also increased shrinkage...
Platinum group minerals (PGMs) are usually exposed to oxidation due to weathering and aging and there is lack of understanding in their interaction with oxygen. We have employed the density functional theory (DFT) to investigate the oxidation mechanism of sperrylite (PtAs2) and platarsite (PtAsS) (100) surface. The computed surface energies and morphologies for sperrylite and platarsite...
Cesium lead iodide perovskites have attracted significant interest due to their rapidly increasing efficiency when used in solar cells applications. Density functional theory was used to investigate the structural,electronic, elastic, and optical properties of CsPbI3, CsPbI2Br, CsPbBr2I and CsPbBr3 perovskite materials. The generalized gradient approximation, GGA-PBE was used to estimate the...
Transition-metal alloys, such as iron-aluminides are significant because of their impact on the industrial sector, such as excellent unique corrosion properties and resistance to high-temperature oxidation, which outperform Ni-based superalloys. Due to their extraordinary resistance to oxidation at high temperatures, Fe-Al based materials have recently received a lot of attention as a...
Surface cationic doping has been deemed one of the most effective methods of reducing the number of trivalent manganese (Mn3+) ions that undergo a disproportionation reaction in lithium manganese oxide-based (LiMn2O4) lithium-ion batteries. However, the effect of surface doping on the major LiMn2O4 surfaces and their interactions with the...
The current operational materials for lithium-ion batteries require improvement to sufficiently support large-scale systems such as the revolutionary electric vehicles and the storage of the sporadic energy garnered from renewable energy sources. Spinel LiMn2O4 is one of the safest and economically viable cathode materials that can provide adequate energy densities. However, LiMn2O4 suffers...
The Kroll process is a widely used technique in the commercial production of titanium. This process involves a magnesiothermic reduction of titanium tetrachloride (TiCl4). Although this process has several advantages, it is, however, not suitable for the development of a continuous reduction process. Recent studies have introduced a magnesiothermic reduction of other transition metal halides...
The Co$_{x}$Ni$_{1−x}$Cr$_{2}$O$_{4}$ (x = 0.75, 0.80, 0.85) were synthesized by co-precipitation technique [1]. The doping of Ni at the Co site was increased in order to understand how this affects the morphology, structural and magnetic properties. All the samples were prepared using co-precipitation techniques and calcined at 900 °C to achieve crystalline and pure phase samples. The...
CoCr$_{2}$O$_{4}$ is a ferrimagnetic material with a cubic Fd$_{3}$m space group belonging to a normal spinel structure attributed to the large octahedral ligand field stabilization energy of Cr$^{3+}$[1]. These spinels belong to a class of mixed oxides in which the Co$^{2+}$ ions occupy the tetrahedral A sites and the Cr$^{3+}$ ions occupy all of the octahedral B sites with the general...
Nanocomposites have gained interest in current research because of the unique properties and scientific significance it has shown[1-2].It was found that composites that comprise of ferrimagnetic(FiM) and antiferromagnetic(AFM) materials exhibit fascinating magnetic phenomena including proximity effect and exchange bias[2,3].These phenomena manifest due to strong exchange coupling between FiM...
TRANSITION METAL CARBONATE PRECURSORS AS CATHODE MATERIALS FOR LI-ION BATTERIES: COMPUTATIONAL AND EXPERIMENTAL STUDY
Tebogo Morukuladi, Noko Ngoepe, Clifton Masedi and Phuti Ngoepe
Materials Modelling Centre, University of Limpopo, Department of Physics, Private Bag x1106, Sovenga, 0727
Email address: tebzamorukuladi@gmail.com
Abstract
The development of next generation cathode...
Capacity degradation and voltage fade of Li2MnO3 during cycling are the limiting factors for its practical use as a high capacity lithium-ion battery cathode. The incorporation of sodium ions in the lithium sites can mitigate voltage decay by limiting transition metal migration, impeding the oxygen loss and also improving lithium diffusion of Li-rich layered host materials. In this work,...
Sodium-ion batteries (NaIBs) have been widely used in energy storage applications such as portable devices and electric vehicles [1]. The demand of lithium rapidly increases year by year, pushing up the price and making lithium resources less affordable. Thus, it is crucial to find alternative technology beyond Li-ion batteries (LIBs) employing abundant elements on earth. Sodium (Na+) becomes...
Hydrogen production by photoelectrochemical water splitting (PECWS) is becoming topical, as clean methods of producing hydrogen are now a necessity. TiO2 is a wide band gap semiconductor material, which is suitable for PECWS by virtue of ease of nanofabrication, excellent photosensitivity and chemical stability among other factors. The present study explores the structural and optical...
In a search for superior magnetic materials with novel properties, including magnetization reversal, magnetocaloric effect, spin switching, spin reorientation and exchange bias effect, focus is on multiferroic materials [1-5]. Single phase multiferroic materials exhibits the coexistence of two or more of the ferroic orderings and can find application in memory devices [2]. RCrTiO$_{5}$...
FIRST-PRINCIPLE STUDIES OF CUBIC Ti2AlV AND TETRAGONAL TiAl2V STRUCTURAL STABILITY
D.M. Tshwane and R. Modiba
Future Production: Manufacturing, Advanced Materials Engineering, CSIR, PO Box 395, Pretoria, 0001, South Africa
DTshwane@csir.co.za
ABSTRACT
TiAlV intermetallic alloys are used as a key functional material in various industries due to their superior properties. However, our...
Broken inversion symmetry is observed in compounds with a spiral ordering, leading to ferroelectricity has attracted recent attention [1]. CoCr$_2$O$_4$ is a compound with a complex conical-spiral spin ordering of ferrimagnetic nature that has a spontaneous magnetization [2]. This observed spiral ordering has induced ferroelectric polarization [3]. The crystal structure of CoCr$_2$O$_4$ is...
This study focuses on the magnetic properties of $Zn_{1-x}Co_xO$, with x = 0.01, 0.03, and $Zn_{0.96}Co_{0.01}Cr_{0.03}O$, synthesized by solution combustion method. X-ray diffraction (XRD) revealed samples are in a hexagonal wurtzite structure. Rietveld refinement gives lattice parameters, a = b = 3.246 Å, and c = 5.201 Å, for $Zn_{0.99}Co_{0.01}O$; matching standard data (PDF#36-1451), and...
Recent rechargeable batteries are mainly based on conventional lithium intercalation chemistry, using lithium transition metal oxides as cathode material with typical capacities of 120-160 mA.h/g. The low energy density and/ or high cost of these cathode materials have limited their large scale production and application in Li ion batteries. Exploration of new cathode materials is consequently...
The SAFARI-1 Research Reactor is a flagship nuclear facility with exemplary operational, maintenance and management records. Notwithstanding its commissioning stemming from 1965, that classifies it as one of the oldest large research reactors in the world, it occupies high international stature as a prominent producer of medical radioisotopes in conjunction with Necsa business units. To...
Chalcogenide alloys exhibit excellent correlated properties essential for thermoelectric and energy storage in non-volatile based memory devices. This work presents an attempt to determine the thermal conductivity using two distinct light scattering methods on chalcogenide alloys in the various structural phases. Thin films of chalcogenide alloys formed from the Pseudo-binary tie line and...
Since the first demonstration of nonlinear optics (second harmonic generation) it is known that it cannot happen in free space: these processes need a medium interaction to happen. It is very common to see lasers with inbuilt frequency conversion enabled by nonlinear crystals. Those crystals, for example, are a medium specifically tailored to maximize the conversion of one specific wavelength...
Abstract (text submission) Pure bulk zirconia (ZrO₂) is a polymorphic oxide that exists in three different low pressure crystal structures below its melting point namely, the high temperature phases cubic and tetragonal as well as the low temperature monoclinic phase [1]. Irradiation of bulk natural zirconia at room temperature along the monoclinic [100]m crystal axis were shown by...
Carbon steels were historically widely used for steam pipes in petrochemical and power generating plants. The microstructure consists of alternative bands of ferrite and pearlite aligned with the rolling direction. During long-term service above 420ºC the lamellar cementite structure either breaks up into spheriodite or converts into its thermodynamical stable phase, graphite, leading to a...
