Three-dimensional (3D) halide perovskites have emerged as a promising class of inexpensive and easy-to-make semiconductors for photocatalytic application in hydrogen evolution due to their exceptional visible light response. Their high sensitivity to humidity, however, resulted in significant instability issues. This led to the development of 2D/3D halide perovskites (HaP), which showed...
A comparison study of nanosized ZnxCo1-xFe2-xAlxO4 (x = 0, 0.2, 0.3, 0.4, 0.5, 0,7, and 0.9) and bulk counterparts obtained by annealing at 1000 0C for 3 hours is presented. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy studies confirmed the formation of cubic spinel structure for both the as-prepared and annealed samples. The as-prepared...
Abstract. Process prediction and optimisation have been regularly conducted in physical systems. While most of the tools used require the introduction and analysis of input–output parameters, often ranges of values are required. The observed non-personalisation of the range of input parameters and the obtained outcome values in the metallurgical processes has prompted the content of this...
Bimetallic thin films of chromium-tin (Cr-Sn) were prepared using electron beam evaporator, the films were prepared such that a layer of chromium was deposited onto a thin film of tin. The first sample was then annealed in the Rutherford Backscattering Spectrometry (RBS) chamber under high vacuum, while probing with alpha particles. The RBS spectra were collected in-situ while annealing at a...
BaAl2O4 /CaAl2O4/AlHO2/Tb2O3/TbAlO3:x% Tb3+ (0 ≤ x ≤ 1.9) mixed phases nanophosphors were developed using sol-gel synthesis. The phase quantification of the XRD results indicated that the mixed phases are composed of the hexagonal (BaAl2O4, CaAl2O4), orthorhombic (AlHO2, TbAlO3) and cubic (Tb2O3) crystal structures. SEM results showed the presence of the nano which enlarged with the increase...
In this work, Ball Milling is investigated as a viable synthesis method for highly crystalline
TiO2-ZnO composites. The composites were verified using various standard techniques.
XRD measurements confirmed the presence of hexagonal wurtzite ZnO and tetragonal TiO2
nano particles. Both XRD and transmission electron microscopy show a mean crystallite size
between 12.7 and 15.0 nm. The blend...
Density functional theory, and molecular dynamics simulations were used to study the nature of binding on Au- and Ag-nanoparticles and 1, 2, and 3-fibrin molecules. In the process, the negative adsorption energies acquired suggest that the fibrin molecules + Au-/Ag-nanoparticles reaction process is exothermic and energetically stable. Moreover, radial distribution functions and radius of...
In this work a two-component density functional theory is employed in the modelling of defects in neutron-irradiated SnO2. Since defects are localized, the local density approximation (LDA) is used which is part of DFT. Although LDA gives a good approximation of positron lifetimes and electron-positron annihilation momentum density, it does not consider the variation nature of the electron...
Dilute magnetic semiconductors (DMSs) offers an alternative pathway towards achieving electronic hybrid devices capable of combining the three critical functionalities of logic, communication and data storage, within a single IC chip. Such DMS hybrid devices can use both voltage and light to simultaneously manipulate both the charge and spin of an electron promising more affordable, compact...
Magnesium batteries have poor cycle performance, which limits their commercial use. In magnesium batteries, sulphur (S) performs poorly and reduces the battery’s performance; however, when selenium (Se) is added, the issue is improved and the material's energy density is enhanced. Therefore, in this study, cluster expansion technique was employed to determine phase changes of mixed...
We are entering an era of large radio and optical astronomical surveys, particularly for the Southern Hemisphere. One challenge is to effectively combine and cross-match source catalogues from surveys in different wavelengths, thereby maximising the science impact of surveys. We use the Likelihood Ratio method to cross-match compact source catalogues extracted from the MeerKAT Galaxy Cluster...
Abstract
Lithium-ion rechargeable batteries, in particular the cathode materials, are now more essential than ever before as improved, reliable, and effective energy storage systems. Lithium cobalt oxide (LCO), the cathode material now in use, has a reputation for being toxic, expensive, and cobalt-scarce. Due to their accessibility, affordability, and non-toxicity, Nickel Manganese...
Structural, electronic, mechanical and optical properties of pseudo-cubic CH3NH3PbI3 were investigated using density functional theory. The predicted values of the stated properties agreed reasonably well with the existing theoretical and experimental data. Optical studies were undertaken so as to probe the photo-physical properties of the material in order to gauge its suitability as the...
Silver and nickel nanomaterials have attract increasing attention for the wide range of applications. Most of their applications are for industrial purposes, high electrical conductivity, automotive catalytic converters, health care, etc. Their applications can be maximized by studying their structural and electronic properties. In this work we utilize molecular dynamics simulation to...
Confocal microscopy is a technique of choice for high resolution imaging of a wide range of sample surfaces. It also plays a vital role in the optical sectioning of imaged materials for 3D reconstruction. Similarly, atomic force microscope (AFM) is renowned for its capability in evaluating the local properties of different samples precisely down to atomic scale. The amalgamation of AFM with...
Arnold Mutubuki[1], Nyasha Joseph Suliali[2] and Johannes Reinhardt Botha[1]
1 Physics Department, Nelson Mandela University, P.O. Box 77000, Gqeberha 6031, South Africa
2 School of Physics, Engineering and Technology University of York, Heslington, York YO10 5DD, United Kingdom
Corresponding author email address: s226046524@mandela.ac.za
Photoelectrochemical water splitting...
Pentlandite ((Fe,Ni)9S8) is a primary source of nickel and is largely found in the Merensky reef which host the largest amounts of base metal sulphides (BMSs) and is also known to host platinum group elements (PGEs). Palladium and rhodium are the PGEs contained mostly in pentlandite, cobalt (Co) is also one of the metal found in association with pentlandite. The milling of pentlandite prior to...
In this study BaAl2O4:x%Gd3+ (0≤ x≤ 1) nanomaterial were prepared using sol-gel mathod. X-ray diffraction (XRD) data revealed that all samples consisted of a single phase of cubic BaAl2O4 structure with no impurities. Fourier Transformation Infrared spectroscopy (FTIR) revealed four absorption bands at 843, 1016, 1416, and 3434 cm-1. The presence of Ba, Al, O and Gd were confirmed by the...
The magnesiothermic reduction of titanium tetrachloride (TiCl4) results in the formation of titanium subchlorides such as titanium trichloride (TiCl3) and titanium dichloride (TiCl2). However, this process occurs extremely fast and it is not suitable for the development of a continuous reduction process. In this study, classical molecular dynamic calculations were performed to understand the...
The gas sensing performance of a material partly depends on its defect property, especially the oxygen vacancy (VO) content [1]. The trace amounts of common impurities such as Cr3+ and N in Ga2O3 nanostructures significantly influence their defect-emission profiles [2,3]. In this work, we investigated the effect of unintentionally doped Cr3+ and N defects in conjunction with the intrinsic...
In lithium-air batteries, metal oxides are frequently regarded as excellent catalysts that help produce stable discharge products and deliver better electrochemical performance. The metal-air battery is a type of electrochemical cell or battery that generates electricity by oxidizing a metal, such as Li, K, Na, or Mg, at the anode and reducing oxygen at the cathode. In this study, we use the...
Density functional theory using full-potential all-electrons linearised augmented plane waves was implemented to study electronic, elastic, and thermoelectric properties of hexagonal CuSe phase. Electronic bands suggest a metallic compound of zero energy gap. Density of states further expose the electron density responsible for this metallic behaviour. Elastic properties reveal mechanical...
Ternary AIIBIVCVII structures have received a great deal of attention from both technological and scientific perspectives due to their optoelectronic properties and both p- and n-type electronic conductivity. Among them, NaVSe2 dichalcogenide compound promises excellent intercalation and high conductivity. However, details on the structural, and electronic properties of NaVSe2 remain limited,...
B Phale1, RR Maphanga2, 3 and PS 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
The structural, elastic, electronic and...
MgCexFe 2-xO4 (0 ≤ x ≤ 0.4) nanoparticles have been produced by the glycol-thermal technique and characterized by X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, and gas sensing analyses. The X-ray diffraction results indicated that a pure cubic spinel phase was formed for samples having a low concentration of Ce, but the high Ce doping (x <...
In the field of the energy transition, developing efficient and cost-effective solar cells is a crucial goal to establish an optimal energy mix. The third generation of photovoltaic cells, which utilize abundant materials and simple processes, has emerged to achieve this goal. Among these, photovoltaic cells based on perovskite materials have demonstrated significant advances, with power...
Herein, a high-performance acetone gas sensor based on pyramid-like Ce-doped In2O3 products was generated using a facile electrospinning approach followed by annealing at 550 ℃. Systematic characterization techniques demonstrated that the introduction of Ce dopant ions into the In2O3 lattice can improve the acetone gas sensing properties by inducing a high concentration of oxygen vacancies at...
The electrochemical deposition was used to synthesize SrS-doped zirconium materials at varying dopant concentrations of 0.01 to 0.03 mol. The surface micrograph of the zirconium doped films is well structured on the surface of the FTO used for the synthesis without any crack or lattice strain. The spectrum is polycrystalline with a cubic structure and a prominent peak at (111) orientation for...
In this study, the plasmonic effect of copper nanorods (Cu NRs) inside PTB7-Th:IEICO-4F to improve light scattering in organic solar cells have been investigated. Copper nitrate (CuNO3) is reduced with poly(vinylpyrrolidone) (PVP) in which the solution is heated in an autoclave to obtain Cu NRs. Cu NRs are deposited in PTB7-TH:IEICO-4F and spin coated on top of glass substrate followed by the...
Nanocrystalline Ni0.5Co0.5RE0.03Fe0.197O4 (RE = Ce, Nd, Gd) were synthesized by glycol-thermal method. X-ray diffraction (XRD) results confirm the formation of single-phase spinel ferrite. The crystallite sizes ranged from 6.29 nm to 9.41 nm which was comparable to results obtained using Williamson-Hall (W-H) method. Lattice parameters were found to vary from 8.356 Å to 8.370 Å depending on an...
Silicene is a two-dimensional structure of silicon which has been synthesized experimentally. It is mechanically and thermally stable and possess the possibility of being easily integrated into the existing silicon technology, hence its importance in semiconductor device technology. However, the performance of any semiconductor material is dependent on the type, stability, and interactions...
The exploration of new electrode materials exhibiting improved electrochemical performance and low cost for high-density lithium-ion batteries (LIBs) applicable in electric vehicles is one of today’s most challenging issues in material research. Li2MnO3, as a prospective high-capacity (459 mAh.g-1) cathode, suffers from capacity degradation and voltage decay during the cycling process....
Producing electrical energy from fossil fuels proves to be a growing concern and requires alternatives for it to be sustainable. The electrical generation capacity is still not enough. Renewable energy (RE) generation faces an uncertain future as most of its generation processes require favorable conditions, the sun must shine or the wind blows. One way to ensure continuous supply of renewable...
Collectors play a key role in determining a minerals floatability behaviour. Variations in chain length have a specific effect on xanthate collectors, which continue to be the most versatile collector for the bulk of minerals, this leads to better recovery rates. This study investigates adsorption energies, bonding behaviour and the interaction of the mercaptobenzothiazole (MBTK) with the...
Platinum tellurides are platinum group minerals (PGMs) predominantly found in the Platreef Bushveld Complex of South Africa, which is one of the leading countries with highest percentages of PGMs. Besides being the important carriers of precious metals, telluride minerals are minor constituents in an ore deposits from a wide diversity of geological environments and they are of significant...
Density functional theory calculations were performed to study the behaviour of Li atom on self-healed various CH divacancies graphane focusing on the reconstructed lattices. The energetic stability, structural and electronic properties of different Li configurations on self constructed topological 5-9-5 and 9-5-9 defects were examined. These lithiated configurations have high binding energy...
Rechargeable batteries have the potential to help meet the ongoing demand for portable energy and to mitigate the energy crisis in countries such as South Africa. These call for the accelerated development of novel and advanced high-energy battery electrode materials. Magnesium-Silicon (Mg-Si) anodes have emerged as attractive alternatives to the graphitic anodes used in current lithium-ion...
Development of low elastic modulus β-Ti alloys for implant application has grown significantly in recent years. In this work, alloy Ti-28.3Nb-13.8Ta-6.9Zr was produced by button arc melting (BAM). Pure metal powders of Ti, Nb, Ta and Zr were pre-mixed and prepared as feedstock powder to the Copper-Hearth BAM. The alloy was manufactured, and heat treated (HT - solution treated + aged). The...
In the present report we demonstrate the synthesis of sodalite NaAlSiO2 nanocrystals via
hydrothermal process. Moreover, the synthesized nanostructured materials were obtained at
different growth time which systematically revealed its effective dependence along with the
crystallinity and surface morphology. In addition, the as-synthesized nanomaterials were
characterized using various...
CdZrS thin films were synthesized by the two-electrode electrodeposition method at different growth voltages (1535-1570) mV with intervals of 5 mV on conductive glass substrate fluorine-doped thin oxide (FTO). Structural, optical, electrical, surface morphology, surface roughness, and elemental composition of the as-prepared and annealed CdZrS thin films were investigated by using X-ray...
Organic solar cells (OSC) will soon be commercialized because of their benefits such as low cost, light-weight, flexibility, and the ability to process for very wide area applications. Polymer semiconductors may have the potential to replace silicon in next-generation solar cells. Despite these benefits, there is still some room for improvement in polymer solar cells power-conversion...
Abstract
Carbon nanotubes (CNTs) are excellent for heat transfer in fluids due to their high thermal conductivity of (>3000 W/mK) and specific heat capacity of (49.11 W/m2 K). They are preferred in industry due to their high thermophysical properties. In this study, CNTs were synthesized using chemical vapour decomposition (CVD). Morphology and structure of the CNTs were revealed using...
iThemba LABS is a facility that houses various research accelerators, including the latest 3 MV TandetronTM accelerator, which was installed in 2017 to replace the 51-year-old 6 MV CN Van de Graaff accelerator. High Voltage Engineering Europa B.V. (HVE) was responsible for installing and commissioning the new accelerator in the Tandetron Laboratory. The accelerator has the ability to...
The demand for energy storage devices with high energy density has increased with the development of renewables occurring. Calcium ion batteries (CIBs) have gained attraction due to their abundance, high energy density, low cost, and low risk. Supercapacitors and Batteries are the currently used energy storage devices with Batteries being the dominant/most used. This study presents...
NiTi-based intermetallic compounds are known as shape memory materials and are frequently utilized in industries like aerospace, machinery, medical applications, and electronics. This is due to their structure memory effect, super elastic behaviour, high tensile strength, and biocompatibility. However, this NiTi alloy is still a contentious material due to its unstable surface and oxidation...
We herein report on the fabrication of patterns using proton beam writing (PBW) and femtosecond laser lithography. In femtosecond laser lithography, high-resolution patterns can be created on semiconductor materials using the energetic photons from a laser source as it has been done for the fabrication of microfluidic lab on chip photonic devices and biochips applications. In the pattern...
The development of radiation shielding for spacecraft found in low Earth orbit (LEO) has been an ongoing campaign since 2001 [1, 2]. In the LEO range, various threats cause extensive degradation of spacecraft materials. Considering organic materials such as polymers have one threat that significantly affects them: atomic oxygen (AO). Atomic oxygen is formed via photo-disassociation of...
Lithium-ion batteries have been widely used as a solution for portable energy storage over the years, however, the rising demand for high-energy-density batteries calls for the design of new high-performing electrode materials. Magnesium-based batteries emerged among alternatives to lithium-ion batteries, however, further studies are still required to help accelerate developments toward their...
Spinel cathode material LiCo2O4 exhibit good electrochemical performance when used in energy storage applications. This is attributed to its high surface-to-volume ratios and shortened Li+ diffusion lengths during cycling. However, some possible flaws have constrained the good electrochemical performance. These flaws include structural changes that carry the risk of structural collapse and...
In recent days, semimetals have become an active branch of materials research. The Platinum Group Mineral (PGM) semimetal Insizwaite (PtBi2) and Maslovite (PtBiTe) are polymorphic systems with interesting electronic properties. Here we report the optimised crystals belonging to the pyrite-type cubic structure which are important electronic systems to investigate both from the point...
Structural, Electronic, Mechanical and Thermodynamic Properties of Ternary NaVS2: DFT Study
L. Mogakane1, P.M. Maleka1, D.M. Tshwane1,2, R.S. Dima1, and R.R. Maphanga1,2
1Next Generation Enterprises and Institution Cluster, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001, South Africa; lmogakane@csir.co.za
2National Institute for Theoretical and Computational...
Current high temperature gas reactor designs use TRISO-coated particles as fuel. The TRISO-coated particle consists of a fuel kernel and coating layers of porous pyrolitic carbon (PyC), inner high-density PyC, silicon carbide (SiC) and outer high-density PyC. The SiC layer serves as the main barrier to fission product release1. However it has been reported that the radioactive fission product...
The need for cleaner, renewable energy to tackle issues such as global warming and the rapid consumption of fossil fuels has led to an increased interest in developing high-energy and high-power density energy-storage devices. While batteries were extensively used for energy storage in the past, they suffer from a limited number of charge cycles and longer recharge times. Electrochemical...
Abstract
Two-dimensional hexagonal boron nitride nanosheets were synthesised using the wet chemical reaction method. X-Ray Diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, Fourier Transform Infrared Spectroscopy, Raman Spectroscopy, UV-visible Spectroscopy and Brunauer-Emmett were used to attain the structural properties of the nanomaterials. Each spectroscopic...
Metal-air batteries have a far higher theoretical energy density than lithium-ion batteries and are frequently proposed as a possibility for next-generation electrochemical energy storage for applications like electric vehicles and grid energy storage. The Na-air battery is an energy storage system with moderate catalytic activity in the Oxygen Reduction Reaction (ORR) and Oxygen Evolution...
The versatility of elastic membranes as building blocks in mechanical vibration has led to their widespread use in various fields of science and technology, including architecture and construction, medical devices, industrial applications, consumer goods, aerospace and defense, energy applications, and the entertainment industry. Their unique ability to stretch and return to their original...
Pyrite is the most common sulphide gangue mineral occurring in base metal sulphide ores around the world. FeS2 is one of the most commonly occurring metal sulphide minerals. Despite its low economic value, its properties have been explored extensively over the years. However, the study of properties of other pyrite-type minerals are still lacking. This work use computational modelling...
ABSTRACT
We report on the synthesis and thermal conductivity of gold nanoparticles (AuNPs) decorated graphene nanosheets (GNs) based nanofluids. The GNs-AuNPs nanocomposites were synthesised using a nanosecond pulsed Nd:YAG laser (wavelength = 1064 nm) to ablate graphite target followed by Au in ethylene glycol (EG) base fluid to obtain GNs-AuNPs/EG hybrid nanofluid. The characterization of...
Class II 6.7 GHz methanol maser emission, first discovered by Menten (1991), is exclusively associated with high-mass star-forming regions. Long-term observational studies have shown that masers are variable on many timescales; this finding was unsurprising as masers are incredibly sensitive to the changes in their local physical environment. A more surprising finding was that of the periodic...
A facile reflux method was used to synthesize the undoped and Au-doped V2O5 nanoparticle powder samples at concentrations ranging from 1 wt% to 5 wt%. XRD, SEM, BET, FTIR and UV-Vis analysis revealed a change in morphology from spherical to nanorod-like nanostructures upon doping with the gold. The Au-doped V2O5 nanostructures tend to increase in surface area, and also become more crystalline...
