Conveners
Poster1: CMPMS
- JAPIE ENGELBRECHT (NMMU)
Ab-intio Density Fuctional Theory has been employed to investigate the stabilities of Li< sub >2< /sub >O, Li< sub >2< /sub >S, Li< sub >2< /sub >O< sub >2< /sub > and Li< sub >2< /sub >S< sub >2< /sub > systems. Calculations were carried out utilizing Plane-wave Pseudopotential method within GGA-PBE using VASP CODE. We found good agreement between predicted data and experimental data of...
Planewave pseudopotential calculations were conducted to predict the phase stability of Pt-Cr binary alloys. The heats of formation are determined for five different phases, L12, A15, DOC, DO'C and tP16 of Pt3Cr and PtCr3. We observed that the cubic L12 Pt3Cr is the most stable structure in agreement with the experiments. The results for PtCr3 indicate the negative heat of formation for the...
The system ZrO2-xSxx is limited by the cases ZrO2 and ZrS2 (x = 0, 2). Physical properties of such systems for 0 < x < 2 are of great interest, but difficult to obtain from first principles calculation. A recently suggested approach, i.e virtual crystal approximation, allows simulation for changes in composition, while retaining a small unit...
In order to investigate the diffusion of indium (In) when an In thin film is coated with a copper (Cu) thin film, thin In/Cu films were grown on a silicon dioxide (SiO2) substrate. Both the In and the Cu layers were grown by electron beam evaporation. The temperature during evaporation of the films ranged between 27 and 38 oC. The In films (500 Å) were coated with Cu...
The behaviour of iodine implanted in highly oriented pyrolytic graphite (HOPG) has been investigated using Rutherford backscattering spectrometry (RBS), scanning electron microscopy (SEM) and x-ray diffraction (XRD). Iodine ions were implanted into HOPG using an energy of 360 keV and a dose of 1×1015 atoms cm-2 at room temperature. The implanted samples were annealed in vacuum at 900 0C,...
Preparation of Er3+, Ho3+ and Tm3+ ions co-doped SiO2 nanoparticle phosphor powders by sol gel method is reported. The morphology and the particle size of the SiO2 host matrix were confirmed by field emission scanning electron microscopy (FESEM). Ultraviolet, visible (UV/VIS) and cathodoluminescence measurements were carried out in order to investigate the optical properties of our powder...
We have investigated the electronic, structural and optical properties of the PtAs< sub >< /sub>2 and PtAsS structures using the density functional theory in the framework of Vienna Ab initio Simulation Package (VASP) code within the generalized gradient approximations of Perdew, Burke and Erzenhof (GGA-PBE) . The total energy calculation of PtAs < sub >< /sub>2 and PtAsS have been...
We investigate the transformation from hematite to ilmenite structure by solid solution approach using ab initio quantum-mechanical simulation technique. The method uses the Density functional theory with the plane-wave (PW) pseudopotential method within the CASTEP code. We performed full structural relaxation allowing lattice parameters and cell violume to change to their mechanical...
Rutile and anatase structured tin dioxide ceramics have been intensively studied in recent years because of their potential in sensing and fuel cells.The present work uses classical molecular dynamics simulations focused on the structure and possible transformation from anatase to rutile tin dioxide.The empirical Buckingham potential has been used to describe the interatomic interactions in...
Rutile and anatase structured tin dioxide ceramics have been intensively studied in recent years because of their potential in sensing and fuel cells. The present work uses classical molecular dynamics simulations focused on the structure and possible transformation from anatase to rutile tin dioxide. The empirical Buckingham potential has been used to describe the interatomic interactions...
The effects of side chain size and spacing on the mobility of the PEO backbone have been studied using molecular dynamics (MD) in Forcite code of Materials studio. The systems investigated contain a PEO chain of 186 ethylene oxide (EO) monomers to which side chains of 5, 6, 7, 8 and 9 PDMS monomers have been attached. The separations of the side chains used are 5, 10, 15, 20 and 50 EO...
Cobalt pentlandite (Co9S8)is the major source of cobalt. Of the several cobalt minerals, cobalt pentlandite is the most abundant and has the widest geographical distribution. This presentation looks at the computer simulation of Co9S8 structure using different computer simulation techniques, i.e. METADISE, VASP. These techniques have been employed...
CeCuGe is one of the few compounds to order ferromagnetically at low temperatures. The compound has been observed to exhibit paramagnetic-ferromagnetic (PM-FM) magnetic transition, TC = 10 K This magnetic ordering has been observed from specific heat (Cp), magnetization, (M(T,B)) and resistivity data. Isothermal magnetization of a hexagonal, highly ordered CeCuGe were measured in order to...
Within the confines of the standard model of rare earth magnetism, the high temperature magnetic properties of rare earth ions in a crystalline environment are identical to the magnetic behaviour of free tri-positive rare earth ions. At low temperatures deviations from free-ion behaviour occur due to the action of an anisotropic crystalline electric field (CEF). For Pr3+-ions...
Graphene characterization and device fabrication often require extensive use of the scanning electron microscopy (SEM) and tunneling electron microscopy (TEM). These techniques involve electron beam irradiation that usually causes defects in materials under investigation. The radiation induced defects may lead to significant damage to the material which may alter its properties, normally an...
Short range biaxial and hydrostatic strains in quantum dots caused by spacer layers affect the aspect ratio to a great extent, leading to variations in the conduction and valence band energy levels. This paper aims to study the effect of the indium mole fraction and thickness of the spacer layer on the size and shape of multi-stack quantum dots grown by metalorganic vapour phase epitaxy....
Amorphous and nanocrystalline silicon carbide thin films were deposited on corning glass 7059 and c-Si (100) substrates using the Hot Wire Chemical Vapor Deposition (HWCVD) and Magnetron Sputtering (MS) techniques. Samples were prepared at low substrate temperatures below 300 degrees celsius and a gas mixture of SiH4/CH4/H2 was used in case of HWCVD. For MS, the temperature of the substrate...
Silicon carbide (SiC) materials have attracted a lot of attention because of their good optical and electrical properties. In recent years there has been an intense focus in research on controlling the optical and electrical properties of amorphous SiC thin films deposited at low temperature of the substrate. SiC has a wide bandgap which can be tuned by varying the carbon content in the...
Hydroxyapatite coating (HAp, Ca10(PO4)6OH2), produced by air plasma spraying, was investigated for depth profiling behavior of phase composition, crystallinity and residual stress using diffractometry techniques. Probing was carried out using conventional 8 keV laboratory X-rays, 11 keV and 100 keV radiations from 2nd and 3rd synchrotron facilities, respectively. The latter employed...
An Auger electron spectroscopy study was performed in order to determine the bulk concentration of S in Fe-S. A number of studies have been performed that employs AES to study diffusion and segregation in metals. The most common application is the use of the technique to determine the diffusion parameters i.e. activation energy (Q) and the pre-exponential factor (D0). This approach makes...
Titania is a cheap and nontoxic polymorphic material of current interest for a variety of technological applications like in gas sensing and photovoltaic cells. Generally, TiO2, with a band gap of 3.2 eV, can only be excited by a small UV fraction of solar light, which accounts for only 3-5% of the solar energy. Various strategies have been pursued including doping with metallic elements...
Ce doped silica has potential applications for a luminescent material as phosphors for cathodoluminescence, scintillators and detectors. Ce ions can occur in a trivalent or a tetravalent state: only the trivalent Ce3+ state with a single 4f electron is optically active, while the tetravalent Ce4+ ion is non-luminescent. X-ray photoelectron spectroscopy (XPS) is a...
MgxZn1-xO films were grown on c-plane sapphire substrates by metal organic chemical vapour deposition. The effects of growth rate and low temperature (280ºC) ZnO buffer layer thickness on the incorporation efficiency of Mg as well as the optical and structural properties of the MgxZn1-xO films were investigated. Low growth rates enhance the segregation of Mg, leading to a magnesium rich...
Fe2O3 nanostructures were synthesized for various pH values on Corning glass substrates by aqueous chemical growth (ACG) using a solution of ferric chloride (FeCl3). It was found that increasing the pH from 1.16 to 5.0 of the solution significantly leads to a modification of the Fe2O3 morphology or orientation from randomly parallel needle shaped rod-like to randomly perpendicular...
Palladium (Pd) and ruthenium (Ru) Schottky barrier diodes were fabricated on (100) Sb-doped n-type germanium using resistive evaporation and electron beam deposition systems, respectively. Electrical characterization of these diodes using current-voltage (I-V) measurements was performed under various annealing conditions. The morphological evolution of the surface was analysed using the...
The AlxGa1-xN materials system is important for realising tuneable LED and laser sources and short wavelength photodetectors. While AlxGa1-xN (x = 0) is fairly known, there is interest in studying the effects of an increasing Al fraction on properties of devices. In particular, on the properties of a bi-metal Ni\ Au Schottky contact. We utilise Current-Voltage (I-V) and the forward...
We investigate the electrical parameters of n- GaN irradiated at room temperature with 5.4 MeV alpha-particles from an americium-241 (Am-241) radio-nuclide source under dark conditions. The radiation damage was studied using current–voltage (I–V) and capacitance –voltage (C–V) characteristics for a total irradiation time of 14 hours at a dose rate of and the corresponding dose range of ....
Measurements of X-rays diffraction (XRD), electrical resistivity (T), magnetic susceptibility (T), and magnetization (µ0H) are repeated for the pseudo-ternary alloy (Ce1xTbx) Pt2Si2. XRD results for all the compositions of (Ce1xTbx) Pt2Si2 system indicate a tetragonal CaBe2Ge2-type structure. (T) results indicate evolution from coherent Kondo lattice to incoherent single ion Kondo...
The Cr-Re alloy system was chosen in order to investigate a previous observation of the co-existence of superconductivity and antiferromagnetism, as well as the possibility of a quantum critical point (QCP) in this alloy system. For the initial studies a Cr86Re14 mother alloy was doped with V in order to decrease the electron to atom ratio, resulting in a decrease in...
The main aim of this project is to synthesize, isolate, identify and characterize graphene, defined as a one-atom layer of hexagonally bonded carbon atoms using mechanical exfoliation method. Moreover, this technique is based on pulling apart the layers of a piece of highly oriented pyrolytic graphite(HOPG) and transfer layers from the graphite onto a SiO2 substrate. Graphene is the first...
The effects of annealing temperature and time on glassy carbon implanted with 360 keV strontium ions at room and high temperatures are reported. The samples were implanted with strontium ions to a fluence of 2 x 1016 ions/cm2 at room temperatures, 350ºC and 600ºC. The room temperature implanted samples were isochronally vacuum annealed at temperatures from 200ºC to...
Hydrogen is the lightest element and it has the highest energy content per unit of weight of any known element and thus, it can be used as a source of clean energy. Previous research studies on hydrogen storage show that storing hydrogen as a solid hydride is preferred compared to liquid and gas because of the very high pressures and low temperatures needed to maintain the system. Hydrogen...
Optical selection rules for the intervalley scattering for direct and indirect transitions are investigated. The non-zero matrix elements of the scattering tensors are derived by the method of vector coupling coefficients. These coefficients are needed for the understanding of Gunn effect.
The diffusion of a dilute S solution in Fe was investigated in order to determine the diffusion path and the energy required, Q, for diffusion in a bulk Fe crystal structure. Different pseudototentials were investigated in order to determine the pseudototential that best describes the ground state of the bulk Fe structure. Pseudototentials that gave a good description of the ground state...
Noble gas ion sputtering combined with Auger analysis has been applied extensively to determine the elemental composition as function of sputtering depth. Data from these depth profiles have been used to determine the sputter yield coefficients (S) of elements that are of fundamental interests in many fields, such as in: sample preparations particularly were the sputter ion source is...
ZnO and PVP capped ZnO nanoparticles were synthesised using the sol-gel method at low temperature with ethanol as a solvent, zinc acetate as a precursor and methanol as the cleaning agent. The influence of temperature on the morphology, structure and the optical properties of the ZnO nanoparticles were investigated. The effect of addition different molar masses of the PVP during the...
A wet chemistry route is an essential method used today to synthesize high quality ZnO nanoparticles and nanorods. It is a novel low cost method to produce nanoparticles and nanorods with relatively high dispersivity. In this study optical properties and morphology of the nanoparticles and nanorods were investigated. The X-ray diffraction (XRD) patterns of both nanoparticles and nanorods...
The existence of the ternary intermetallic compound CeRh2Sn2 has been known since the crystallographic report of Selsane et al on the CeM2Sn2 family of compounds in which M is a d–electron element. The crystal structure is well ordered and the sole magnetic species, Ce, occupies a unique symmetry site in the unit cell. Subsequent studies into...
The novel ternary intermetallic compound Ce6Pd12In5 forms in a well-defined atomic stoichiometry with a hexagonal crystal structure (space group P63/mcm) and a unique atom in each of the crystallographic sites available in this space group. The bonding lengths are comparatively short and suggest strong interaction especially between Ce and Pd...
We present specific heat, electrical resistivity, susceptibility, and thermopower measurements on the two novel intermetallic compounds CeFe2Al8 and CeCo2Al8. They form in an orthorhombic crystal structure of space group Pbam. In the unit cell representation Ce atom occupies only one lattice site,having Ce-Ce interatomic distance of 4.03Å....
Recent measurements on an antiferromagnetic (AFM) Cr0.978Al0.022 alloy single crystal suggest that the triple point (TP) on the magnetic phase diagram (MPD) might be a special type of critical point. This suggestion is further investigated here through electrical resistivity and specific heat measurements on a series of Cr1-xAlx alloy single...
Traditionally magnetic forces are supposed to act on moving electric scalar charges and the hitherto undetected Dirac’s magnetic (scalar) charges, and that work done by such forces is always zero. Any possible evidence to the contrary is vehemently denied in order to justify this long held myth. Following our recently developed and validated concept of magnetic vector charges as sources of...
Metallurgical products play an important role in everyday life. The search for alloys with better material properties such as strength, wear and corrosion resistance continues to this day. In addition to these desirable properties, the search for ways to reduce production costs and time has led to a large amount of research being conducted on the processes which determines the material...
The optical and structural properties of ZnO grown with a mixture of oxygen and nitric oxide as oxidants are investigated. With R defined as the ratio of oxygen to nitric oxide molar flow rates, samples grown with R ≥ 1 (i.e. a higher low rate of oxygen compared to nitric oxide) reveal a 3D growth mode with columns perpendicular to the substrate, while for R < 1 a preferential 2D growth...
Non-resonant microwave absorption measurements at 9.4 GHz(X-band)using electron spin resonance spectrometer (ESR), were carried out on pulsed laser deposited(PLD)polycrystalline FeSi thin films grown on Si(111)substrate. The low-field microwave absorption(LFA)properties of the films were investigated as a function of DC modulation field, temperature, microwave power and angle. The DC field...
SrGa2S4:Ce3+ thin films are promising for full colour thin-film electroluminescent (EL) and field emission displays (FED’s) because of its good optical properties. These films were previously prepared using several different techniques such as sputtering (RF), molecular beam epitaxy (MBE), reactive multi-source deposition (MSD), metal-organic chemical vapour...
Surface mapping of quantum well structures using photoluminescence measurements is ideal for determining the overall behaviour of such samples with regard to their chemical composition and well-width fluctuations. In some areas where the structural variations are large over a sample, photoluminescence mapping can yield information which would otherwise require several samples to be grown....
Nano-pahsed structures based on metal-dielectric composites also called cermets (Ceramic-Metal) are considered among the most effective spectrally selective solar absorbers. For high temperature applications (stable up to 650°C) noble metals nanoparticles and refractory oxide host matrices are ideal as per their high temperature chemical inertness and stability: Pt/Al2O3 cermet...
ZrN films were deposited on Si<100> substrates, Al and brass strips by DC magnetron sputtering under varying conditions of power, pressure, argon and nitrogen gas flow rates as well as temperature and characterized by SEM, AFM, RBS, resonant RBS, and XRD. The films are transparent and semiconducting. They tend to absorb oxygen. The films were found to adhere well to the substrates. The...
CaTiO3 exhibits a Perovskite structures that has an ABO3 stochiometry where A and B represent metal cations with a combined charge of 6+ valency and O with 6- valency, and thus bring about charge neutrality to the compound. Upon introducing Pr3+ ions in the site of Ca2+ ions, charge imbalance occurs by introducing a 7+ valency, and this force the material to compensate for this effect by...
There has been a growing demand for quantum cutting and upconverting efficient nano luminescent materials during the last decades. Wide band gap luminescent materials, specially the fluoride, are one of the major role players. Due to a number of advantages such as the excellent transparency in theinfrared (IR) to far ultraviolet (UV) range and low-energy phonons as well as low toxicity...
Previous studies in our laboratory on the (Cr100-xAlx)95Mo5 alloy system through electrical resistivity and magnetoelastic measurements suggest that spin-density-wave (SDW) antiferromagnetism is fully suppressed down to 4 K in the concentration range 2.0 ≤ x ≤ 5.0 at.% Al. The current interest in quantum criticality in Cr and Cr alloy systems...
Zinc-oxide nanoparticles are well known for their novel optical and electronic properties for applications in various fields such as solar cells, ultra violet shielding, gas sensors, paint and heat mirrors. We report on the relation between the structure and optical properties of ZnO nanoparticles synthesized via the sol-gel technique, with specific emphasis on the effect of growth and...
Porphyrins are macro-cycles often organized into nano-scale structures which perform many of the essential light-harvesting-, electron- and energy-transfer functions in various natural and synthetic systems. In addition to the sub-picosecond charge generation and transfer, they exhibit various shapes and functional properties that make them useful for the construction of ultrafast...
Presently Ca AlxOy:Tb green phosphors are mainly prepared by the solid-state process which is more feasible than others in terms of operation and large-scale production. However, the raw materials are usually not mixed well and very high temperature is needed to synthesize the final powder using the solid-state process. In order to solve these problems, Terbium ion...
Crystalline lead sulfide (PbS) nanorods were synthesized by chemical bath deposition (CBD) method using the mixed aqueous solutions of lead acetate, thiourea and ammonium solution. The lead acetate concentrations were varied in the deposition process to determine the effect thereof. The temperature of the bath was maintained at 80ºC. The final yields were characterized for structural,...
Cobalt sulphide nanoparticles are one of the most complex and challenging particles to synthesize due to strongly reducibility of the cobalt ion and the oxidizable nature of the sulphide ion. Cobalt sulphide therefore exist in various phases with different compositions including Co4S3, Co9S8, CoS, Co1-xS, Co3S4, Co2S3 and CoS2. Herein, we describe the synthesis of CoxSy nanoparticles;...
Rare earth oxysulfide materials exhibit high luminescence efficiency as well as excellent chemical stability. These materials are widely used as luminescent host materials of several commercially available red emitting phosphors. However, there still remain issues affecting the operational parameters such as luminescence efficiency, stability against temperature, high color purity and long...
Tb3+-activated calcium silicate (CaxSyyOz:Tb3+) nanophosphors have been synthesized by means of simple and low temperatures (500°C) using the solution-combustion of corresponding metal nitrate, TEOS and urea solution mixtures. The structural evolution of the phosphor was studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and the luminescence properties of the...
Tb3+-doped SrZnAl2O4 nanocrystalline phosphor with good crystallinity were successfully prepared by a combustion method at a relatively low temperature (500o-C), using urea as fuel and metal nitrates as precursors. The effects of Sr and Zn concentrations on the structure and luminescent properties of the material were investigated. In addition,...
Barium-substituted phosphor powders of (Ba1-xSrx)Al2O4:Eu2+ ;Nd3+ composition were prepared by combustion method at an initiating temperature of 5000C, using urea as reducer. The powders were then annealed at higher temperatures of 8000C and 10000C for 3 hours. Their crystallinity and phase...
The study of annealing effects on platinum binary systems has both the fundamental and applied aspects. It is due to the fact that the formation of ordered domains increases the strength and surface hardness and could also have an impact on surface activity and chemical properties. The changes of mechanical, physical and chemical properties caused by annealing could be of significant...
Pr3+-Tb3+, and Pr3+-Eu3+ ion pairs co-doped in SiO2 matrix were prepared by a sol-gel method. The photoluminescence (PL) measurements revealed the red and green emissions centred at 614 nm (5D0-7F2) and 541 nm (5D4→7F5) for single doped Eu3+ and Tb3+ ions in SiO2, respectively. Co-doping of Eu3+ and Tb3+ ions with Pr3+ in SiO2 showed that the energy transfer between Pr3+ and nearest Eu3+...
The concentration of any dopant in a semiconductor can usually easily and readily be established using the plasma resonance minimum. Infrared reflectance spectroscopy was used to assess the doping of SiC wafers by phosphor implantation. However, results obtained did not match the theoretical predictions. The problem was investigated, including an assessment of the applicable theory. ...
The magnetocaloric effect (MCE) may become strongly enhanced in systems exhibiting a second order magnetic phase transition due to critical behaviour of the order parameter in close proximity of the transition region. Recently it has been shown that, analogous to the order parameter, the MCE shows scaling behaviour with the applied magnetic field along the critical isotherm. It has been...
The importance of gold for scientific use is of fundamental importance to research and technology developments. The bulk gold shows reluctance to participate in chemical reactions, the effect which has been corrected by the change in the size towards nanoclusters and, this makes the study of temperature effects on gold very important. We have performed molecular dynamics simulations on...
The interaction of Pd and SiC samples during thermal annealing were investigated using x-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS) as well as Scanning Electron Microscopy (SEM). Two sample configuration were used (1) the palladium (50nm) was deposited onto a degreased 6H-SiC substrate and (2) palladium ions were implanted into the 6H-SiC substrate at room...
There is a general misunderstanding regarding the creation of Frenkel pairs in the vicinity of the observed critical temperature Tc in superionic materials. The measured conductivity increases sharply at a temperature coinciding with the deviation of temperature-dependent lattice constant from 6.2086 A. Frenkel pairs responsible for superionic conduction are gradually generated well below...
Previous experimental investigations have only shown, without explanation, that the pre-exponential factor (D0), in the diffusion coefficient of Sb segregating in Cu, is dependent on the surface orientation of a crystal. In this study, the surface concentration of Sb in a Sb doped Cu(111/110) bi-crystal was measured using a method combining AES and linear temperature heating. ...
In 2003, photoluminescence emission in tin dioxide nanoribbons was reported and it was later demonstrated that the absorption of nitrogen dioxide by these structures quenches the intensity of visible light emission in SnO2 nanobelts which suggested he possibility of developing a new class of contactless devices based on gas sensitive optical devices. The motivation behind this project is to...
The binary compound CeCu5 is an archetypal heavy-fermion Kondo lattice with an antiferromagnetic ground state. Strong hybridization effects between the localized 4f-electron moment and conduction electrons result in incoherent spin scattering in the electronic transport at high temperatures, but with an effective magnetic moment nearly equal to that of the free-ion...
Since the first report of the anomalous magnetic and electronic phenomena in CeRu2Al10 this intermetallic class of compounds, incorporating also members with elements Os and Fe in the place of Ru, have attracted considerable interest. N spite of large interatomic distances antiferromagnetic order sets in at TN =27 K in the ru and Os derivatives, with simultaneous...
It is evident that the Eu2+ ion acts as a luminescent centre emitting in the blue (λmax ~ 440 nm) spectral region for CaAl2O4:Eu2+. The R3+ ion is believed to act as a trap or somehow modify the trap properties in these phosphors. Despite a large number of research on the phenomenon the mechanism of the persistent luminescence of the...
Polycrystalline diamond (PCD) cylindrical cutters used in oil well drilling are susceptible to fracture due to the hostile environment of randomly occurring high impact loads. These cutters commonly consist of a PCD layer sintered onto a cobalt-tungsten carbide (Co-WC) substrate. The fact that the cutters fail after repeated use gives rise to the possibility of fatigue type processes in...
Vanadium dioxide falls into the category of smart thermochromic materials, one where the property of the material changes due to the effect of temperature. High quality pure thermochromic thin films of vanadium dioxide were prepared by using two physical methods, Rf-reactive sputtering and pulsed laser deposition methods. These deposition methods were used to study the effect of deposition...
Different compositions of Ti-Pt were varied within the B2 region i.e. 45-55 at% Pt using solid solution method employed in CASTEP code. The Ti50Pt50 structure was found to be more stable as compared with other different compositions with the heats of formation of -0.8584 eV. We also observed that the more we increase the Ti and decrease the Pt composition, the change...
We report on the characterization of commercially terbium doped gadolinium oxysulfide (Gd2O2S:Tb) phosphor and the degradation of the Gd2O2S:Tb green phosphor for its application in CRT screens. As a result, degradation of the cathodoluminescence (CL) intensity during irradiation of the powder with 2 keV electrons in an oxygen pressure of 1 x 10-6 Torr was studied. The ESSCR mechanisms was...
Recent studies have employed manganese dioxide (MnO2) catalysts to improve the efficiency of Li-air batteries, while other studies have revealed that the Li/O2 cell can be recharged with high efficiency without a catalyst using an appropriate porous carbon electrode. Interestingly, charge voltages of these cells are similar to those of the MnO2, while both...
