CS Phase Research Articles

Auto‐regulated radial base function structure implementation in the hybrid and ensemble hybrid domains to assess the hardened properties of novel mixture high performance concrete

AbstractThe mechanical properties of concrete, such as compressive strength and slump flow rates, are very nonlinear. For academics, it is crucial to forecast these qualities while creating new building methods. Such capabilities should be developed to lower the cost of expensive tests and increase the precision of the measurements. The goal of this study is to create an radial basis function neural network to describe the characteristics of hardness in high‐performance concrete (HPC) mix. Metaheuristic techniques were used to enhance the RBFNN's functionality. A dataset of 181 HPC mixes comprising ecologically beneficial ingredients, such as fly ash and silica fume, was used for training and evaluating the capabilities of the proposed hybrid models. According to the modeling process based on sensitivity analysis of input parameters and the results of hybrid models, the model combined with the multiverse optimization algorithm (MVO) had a higher correlation between the predicted and observed CS and slump values than the model combined with three optimization algorithms in terms of the R2 index being the maximum value of 0.984 in the tasting phase of CS and SL estimation. While evaluating two mechanical aspects of HPC samples, the of the model coupled with the MVO algorithm reconfirmed its accuracy being 3.59.

Mean transverse energy, surface chemical and physical characterization of CERN-made Cs-Te photocathodes

Cesium telluride photocathodes are known to offer high quantum efficiencies under UV illumination combined with good lifetimes compared to other semiconductor photocathodes, making them very popular electron sources for particle accelerator applications. The development of photocathode preparation, characterization, and related expertise at a single accelerator laboratory can be challenging, expensive, and time consuming. Recognizing this, we explored the use of a custom-designed ultrahigh vacuum suitcase for transportation of CERN-made (Switzerland) cesium telluride photocathodes to Daresbury Laboratory (UK) for characterization. We report the synthesis and characterization of a batch of four cesium telluride photocathodes corresponding to our second attempt of transport, following design and process improvements through lessons learned from our first attempt. The photocathode characterization involved, where possible, measurements of the surface elemental composition using x-ray photoelectron spectroscopy (XPS), surface roughness with an in-vacuum scanning tunneling microscope (STM), and quantum efficiency (QE) measurements. Transverse energy distribution curves were obtained over a wide range of illumination wavelengths using the transverse energy spread spectrometer (TESS) at room- and cryogenic temperatures, and the values for mean transverse energy (MTE) were extracted. The photocathodes exhibited distinct thicknesses ranging from ∼50 to ∼120 nm and significant MTE beyond the photoemission threshold which is attributed to the presence of CsxO and Cs phases, as confirmed by XPS analysis. The photocathode that exhibited no carbon or oxygen contamination was measured to have the highest QE of 2.9% at a wavelength of 265 nm at the end of the performance characterization process. The results presented herein offer an insight into the achievements possible through international collaborations by successfully utilizing long-distance transportation of photocathodes by land under ultrahigh vacuum conditions. Published by the American Physical Society 2024

Microstructural phase evolution and strength development of low-lime calcium silicate cement (CSC) paste incorporating ordinary Portland cement under an accelerated carbonation curing environment

Low-lime calcium silicate cement (CSC) is a CO2-reactive cement that utilizes the carbonation products of low- or non-hydraulic C2S, C3S2, and CS phases under H2O- and CO2-rich conditions. However, the reactivity and compressive strength of the CSC require further improvement. Therefore, this study aims to investigate the effects of blending ordinary Portland cement (OPC) as a reactive source into CSC on the initial reaction kinetics, phase evolution, and compressive strength development during carbonation curing. To assess the effects of blending CSC and OPC, CSC was substituted by OPC with the incremental ratio of 20 wt%. Notably, the CSC sample with 20 wt% OPC incorporation exhibited the highest compressive strength, which increased by up to 2.5 times compared to the pure CSC paste. Analysis of the microstructural phase evolution revealed that this significant increase in compressive strength was attributed to the strong mechanical interlocks between the rhombic CaCO3 crystals, which were reinforced by a substantial amount of vaterite.

Effects of thermal activation on the hydration performance of lithium slag–cement composite binder

In order to enhance the utilisation efficiency of lithium slag (LS) in cement-based materials, calcification and thermal activation of LS were conducted, and the activation mechanism was analysed. Results showed that gypsum and spodumene in LS decomposed at high temperature by way of calcification and thermal activation, and spodumene as well as limestone calcination decomposed at high temperature, to generate more CS, CA and other mineral phases. Calcification and thermal activation could enhance the activity of LS to participate in pozzolanic reaction, and generate the formation of more hydration products. After calcification and thermal activation of LS, the hydration exothermic peak, the total amount of hydration heat and the hydration production of LS composite binder were significantly increased. The hardened matrix was more compact with less porosity. Compared with cement mortar incorporating raw LS, the incorporation of calcified and thermally activated LS enhanced the compressive strength of cement mortar at 3, 7 and 28 days by 25.8, 13.4 and 20.5%, respectively.

Solvent casting‐particulate leaching synthesis of a nano‐SiO2/chitosan composite scaffold for potential use in bone tissue engineering

AbstractIn this work, a three‐dimensional (3D) scaffold comprised of chitosan and SiO2 nanoparticles (NPs) (CS/SiO2) was synthesized for bone tissue engineering. The scaffold was synthesized using a combination of solvent casting and salt leaching methods. The nanoparticle sizes were controlled by hydrothermal treatment with the aid of cetyltrimethylammonium bromide (CTAB), which was then used as a bio‐inorganic component of the composite scaffold. Various methods, such as SEM, FTIR, XRD, and liquid substitution, were conducted to determine the morphology, structure, pore sizes, and porosity of the synthesized scaffolds and the interaction between the SiO2 and CS phases. The mechanical properties of the composite scaffolds were evaluated by testing their tensile strength. The results showed that the synthesized 3D CS/SiO2 scaffolds exhibited porous structures with suitable average pore sizes ranging from 198 to 269 μm and porosities from 70.99 to 73.23%, respectively. The tensile strengths of the CS/SiO2 scaffolds were around 1.57‐1.83 MPa, matching well with those of cancellous bone. These appropriate values in terms of pore size, porosity, and tensile strength suggest that CS/SiO2 scaffolds could support cell migration, growth, and distribution. The synthesized CS/SiO2 scaffolds would be potential biomaterials for bone tissue engineering applications.

Carbon-based monochalcogenides for efficient solar and heat energy harvesting

A new generation of two-dimensional (2D) material has captivated significant attention in the energy conversion field owing to their promising optoelectronics and thermoelectric applications. The present work involves the systematic investigation of fundamental properties of single-layered 2D carbon-based monochalcogenides (CS, CSe, CTe) with planar, buckled and puckered geometry within the framework of density functional theory (DFT). The structural and lattice dynamics analysis disclose that puckered and buckled configurations are energetically and dynamically stable whereas planar structures depict instability. The anisotropic group velocity of longitudinal acoustic (LA) and transverse acoustic (TA) phonon modes in puckered systems may render the characteristics thermal transport properties. Additionally, for the first time, we scrutinized the thermoelectric and optical properties of these materials. At room temperature, the electron carrier mobilities are 174.698 and 160.830m2V-1s-1 of puckered and buckled CS systems, respectively are highest among all structures. The computed Seebeck coefficient, electrical conductivity and power factor manifests the high thermoelectric transport properties of puckered CS material. Further, the calculated solar parameters demonstrate an exceptionally high-power conversion efficiency of 19.61 % for puckered CTe. Present work indicates that puckered phase of CS and CTe show their potential for the heat and solar energy harvesting devices, respectively.

Gypsum, crop rotation, and cover crop impacts on soil organic carbon and biological dynamics in rainfed transitional no-till corn-soybean systems.

Soil organic carbon (SOC), a core soil quality indicator, is influenced by management practices. The objective of our 2012-2016 study was to elucidate the impact of gypsum, crop rotation, and cover crop on SOC and several of its biological indicators under no-till in Alabama (Shorter), Indiana (Farmland), and Ohio (Hoytville and Piketon) in the USA. A randomized complete block design in factorial arrangement with gypsum (at 0, 1.1, and 2.2 Mg/ha annually), rye (Secale cereal L.) vs no cover crop, and rotation (continuous soybean [Glycine max (L) Merr., SS] vs corn [Zea mays, L.]-soybean, both the CS and SC phases) was conducted. Composite soils were collected (0-15 cm and 15-30 cm) in 2016 to analyze microbial biomass C (SMBC), SOC, total N, active C, cold and hot-water extractable C, C and N pool indices (CPI and NPI), and C management index (CMI). Results varied for main effects of gypsum, crop rotation, and cover crop on SOC pools, total N, and SOC lability within and across the sites. Gypsum at 2.2 Mg/ha increased SMBC within sites and by 41% averaged across sites. Likewise, gypsum increased SMBC:SOC, active C, and hot-water C (as indicators of labile SOC) averaged across sites. CS rotation increased SOC, active C, CPI, and CMI compared to SS, but decreased SMBC and SMBC:SOC within and across sites. CPI had a significant relationship with NPI across all sites (R2 = 0.90). Management sensitive SOC pools that responded to the combined gypsum (2.2 Mg/ha), crop rotation (CS), and cover crop (rye) were SMBC, SMBC:SOC, active C, and CMI via SMBC. These variables can provide an early indication of management-induced changes in SOC storage and its lability. Our results show that when SOC accumulates, its lability has decreased, presumably because the SMBC has processed all readily available C into a less labile form.

Additive-Assisted Optimization in Morphology and Optoelectronic Properties of Inorganic Mixed Sn-Pb Halide Perovskites.

Halide perovskite solar cells (HPSCs) are promising photovoltaic materials due to their excellent optoelectronic properties, low cost, and high efficiency. Here, we demonstrate atmospheric solution processing and stability of cesium tin-lead triiodide (CsSnPbI3) thin films for solar cell applications. The effect of additives, such as pyrazine and guanidinium thiocyanate (GuaSCN), on bandgap, film morphology, structure, and stability is investigated. Our results indicate the formation of a wide bandgap (>2 eV) structure with a mixed phase of tin oxide (SnO2) and Cs(Sn, Pb)I3. The addition of pyrazine decreases the intensity of SnO2 peaks, but the bandgap does not change much. With the addition of GuaSCN, the bandgap of the films reduces to 1.5 eV, and a dendritic structure of Cs(Sn, Pb)I3 is observed. GuaSCN addition also reduces the oxygen content in the films. To enable uniform film crystallization, cesium chloride (CsCl) and dimethyl sulfoxide (DMSO) additives are used in the precursor. Both CsCl and DMSO suppress dendrite formation with the latter resulting in uniform polycrystalline films with a bandgap of 1.5 eV. Heat and light soaking (HLS) stability tests at 65 °C and 1 sun for 100 h show all film types are stable with temperature but result in phase segregation with light exposure.

Phase behaviors of chitosan/lignosulfonate mixed solutions

ABSTRACT The positively chitosan, CS, and negatively lignosulfonate, LGS, were statically mixed forming a series of mixed solutions. Experimentally, the light brown LGS solution was slowly flowed into the colorless CS solution to form the as-prepared CS/LGS mixed solutions. These mixing solutions presented regular bi-phases taking the LGS phase at the top and the CS phase at the bottom where the difference is the phase thickness varied with the mixing ratio variety. To keep the static mixing condition up to the 3rd, 12th and 15th days, these CS/LGS mixed solutions presented two-phase change tendencies because the CS percent greater samples kept the bi-phases and the LGS percent greater samples presented a tri-phases with a new darker yellow phase at the bottom and a new light yellow phase at the middle. This indicated that the statical mixing time has caused the electrostatic interaction occurrence between the CS and LGS solutions when the reaction degree was influenced by the mixing ratio. The particle size for the CS/LGS mixed solutions with the mixing ratio at 70/30 and 30/70 vol% both after static mixing of 15 days was analyzed and found it was smaller at about 200–300 nm in the upper phase and greater at about 1100–1300 nm in the bottom phase corresponding to the formed micelles and the precipitated aggregates, respectively. Recorded dynamic conductivity revealed that the electrostatic interaction between the CS and LGS strongly occurred after static mixing of about 300 s and the start time was controlled by the mixing ratio, especially the LGS percent.

Polyphosphazene microspheres modified with transition metal hydroxystannate for enhancing the flame retardancy of polyethylene terephthalate

AbstractA novel PZS@CS hybrid structure was synthesized for enhancing the flame retardancy of polyethylene terephthalate (PET). The PZS@CS hybrids showed significant flame retardance. For example, the incorporation of 6 wt% PZS@CS obviously brought about an 8.8% increase of limiting oxygen index value (29.3%) and passed the vertical burning test UL‐94 V‐0 level, accompanied with the sharp reduction of heat and smoke release. The flame retardant mechanism of PZS@CS hybrids was fully studied by the Thermogravimetric Analysis (TGA), pyrolysis‐gas chromatography‐mass spectrometry, and Raman methods, and the results showed that the improvement of flame retardancy was mainly ascribed to the synergistic effect of PZS and CS phases in both the condensed and the gas phase. Rheological results showed that PZS@CS hybrids improved the melt complex viscosity of PET composites and the well compatibility of PET matrix and PZS@CS hybrids was also proved by the improvement of mechanical properties.

Ternary selenides A2Sb4Se8 (A = K, Rb and Cs) as an n-type thermoelectric material with high power factor and low lattice thermal conductivity: importance of the conformationally flexible Sb-Se-Se-Sb bridges.

We investigated the thermoelectric properties of the layered ternary selenides A2Sb4Se8 (A = K, Rb and Cs) and the lattice thermal conductivity of K2Sb4Se8 on the basis of DFT calculations, to find that these selenides are a high-performance n-type thermoelectric material. The Seebeck coefficients and power factors calculated for the electron carriers of A2Sb4Se8 (A = K, Rb and Cs) are greater than those of the well-known thermoelectric materials Bi2Te3 and PbTe. The lattice thermal conductivity κlatt of K2Sb4Se8 is comparable to that of PbTe, well-known for its low lattice thermal conductivity. In terms of both electronic and phonon structures, the structural parts of the A2Sb4Se8 (A = K, Rb and Cs) phases crucial for their thermoelectric properties are the conformationally-flexible Sb–Se–Se–Sb bridges that interlink between their structurally rigid units.

Chemical Properties of Metal-Silicates Rendered by Metal Exchange Reaction

Calcium-silicates and calcium-silicate-hydrates (CS and CSH) are well-known as the most important building material, cement. Both CS and CSH phases react fast with CO2 from the atmosphere. Due to t...

One-step immobilization of cesium and strontium from alkaline solutions via a facile hydrothermal route

Hydrothermal treatment of coal fly ash cenospheres (Si/Al = 2.7) as a glassy source of Si and Al was carried out in 1.5 M NaOH at 150 °C in the presence of Cs+ and Sr2+ to study the possibility of Cs+ and Sr2+ immobilization in mineral-like compounds. Systems Na2O-H2O-(SiO2-Al2O3)glass, Na2O-Cs2O-H2O-(SiO2-Al2O3)glass with Cs+/Na+ ratios of 0.05 and 0.5, and Na2O-SrO-H2O-(SiO2-Al2O3)glass with Sr2+/Na+ ratios of 0.25 and 0.025 were under study. Structure, composition and morphology of solid products were characterized by PXRD, SEM-EDS and STA methods. In the Cs+/Sr2+ free systems the deep crystallization of cenosphere glass takes place resulting in hollow polycrystalline analcime microspheres. Microsphere solids including phases of ANA topology (analcime, pollucite or analcime-pollucite solid solutions) and Cs+/Sr2+ silicates are produced as Cs+ and Sr2+ immobilized forms in the Cs+/Sr2+ bearing systems. The degree of Cs+ and Sr2+ recovery from alkaline solutions was 90–99%.

Light absorption of organic carbon emitted from burning wood, charcoal, and kerosene in household cookstoves

Household cookstove emissions are an important source of carbonaceous aerosols globally. The light-absorbing organic carbon (OC), also termed brown carbon (BrC), from cookstove emissions can impact the Earth's radiative balance, but is rarely investigated. In this work, PM2.5 filter samples were collected during combustion experiments with red oak wood, charcoal, and kerosene in a variety of cookstoves mainly at two water boiling test phases (cold start CS, hot start HS). Samples were extracted in methanol and extracts were examined using spectrophotometry. The mass absorption coefficients (MACλ, m2 g−1) at five wavelengths (365, 400, 450, 500, and 550 nm) were mostly inter-correlated and were used as a measurement proxy for BrC. The MAC365 for red oak combustion during the CS phase correlated strongly to the elemental carbon (EC)/OC mass ratio, indicating a dependency of BrC absorption on burn conditions. The emissions from cookstoves burning red oak have an average MACλ 2–6 times greater than those burning charcoal and kerosene, and around 3–4 times greater than that from biomass burning measured in previous studies. These results suggest that residential cookstove emissions could contribute largely to ambient BrC, and the simulation of BrC radiative forcing in climate models for biofuel combustion in cookstoves should be treated specifically and separated from open biomass burning.

Distribution of Rb, Ga and Cs in agricultural land soils at European continental scale (GEMAS): Implications for weathering conditions and provenance

Agricultural soil (Ap-horizon, 0–20 cm) samples were collected from a large part of Europe (33 countries, 5.6 million km2) as part of the GEMAS (GEochemical Mapping of Agricultural and grazing land Soil) soil mapping project. The soil data have been used to provide a general view of element mobility and source rocks at the continental scale, either by reference to average crustal abundances or to normalised patterns of element mobility during weathering processes. The survey area includes a diverse group of soil parent materials with varying geological history, a wide range of climate zones, and landscapes.Total concentrations of Rb, Ga, and Cs in European soil were determined by XRF (X-ray fluorescence spectrometry). In addition, hot aqua regia available element concentrations were analysed by inductively coupled plasma-mass spectrometry ICP-MS. Their spatial distribution patterns are shown in geochemical maps. The spatial distribution of Rb, Ga and Cs in Ap soil is quite comparable for the aqua regia and XRF results. The Cs spatial pattern reflects best the large difference between trace element concentrations in northern Europe with predominantly low concentrations and southern Europe with approximately two times higher values. The maximum extent of the last glaciation is visible as a clear concentration break on the map. Lithology of the underlying bedrock is inferred as the major source of geochemical anomalies. In search for characterising the soil parent material and degree of weathering, the soil data were examined for Ga and Cs using two methods. First, the estimated degree of extractability DEi of an element in a sample was calculated by dividing aqua regia available concentrations by the total concentrations obtained by XRF analysis for Al, Na, Ca, K, Rb, Ga and Cs. The different DEi were investigated for 10 geological parent material subgroups (alkaline rocks, granite, calcareous rocks, basalt-mafic rocks, unclassified lithologies, Precambrian granitic gneiss bedrocks, loess, organic soils, schist and soil developed on coarse-grained sandy deposits). The role of clay as main carrier of Ga and Cs phases was inferred for soils developed on several types of bedrock such as granite, gneiss and alkaline rocks. Additionally, an affinity of Cs for loess and carbonate rocks has been observed.

Mott Transition in the A15 Phase of Cs_{3}C_{60}: Absence of a Pseudogap and Charge Order.

We present a detailed NMR study of the insulator-to-metal transition induced by an applied pressure p in the A15 phase of Cs_{3}C_{60}. We evidence that the insulating antiferromagnetic (AFM) and superconducting (SC) phases coexist only in a narrow p range. At fixed p, in the metallic state above the SC transition T_{c}, the ^{133}Cs and ^{13}C NMR spin-lattice relaxation data are seemingly governed by a pseudogaplike feature. We prove that this feature, also seen in the ^{133}Cs NMR shift data, is rather a signature of the Mott transition which broadens and smears out progressively for increasing (p,T). The analysis of the variation of the quadrupole splitting ν_{Q} of the ^{133}Cs NMR spectrum precludes any cell symmetry change at the Mott transition and only monitors a weak variation of the lattice parameter. These results open an opportunity to consider theoretically the Mott transition in a multiorbital three-dimensional system well beyond its critical point.

Solar neutrino spectrum of quark nugget dark matter

It has recently been claimed that dark matter in form of quark nuggets cannot account for more than 20% of the dark matter density. This claim is based on constraints on the neutrino flux in 20-50 MeV range where the sensitivity of underground neutrino detectors such as Super-Kamiokande have their highest signal-to-noise ratio. We argue that this claim depends crucially on the assumption that the annihilation of visible baryons with an antiquark nugget will generate a neutrino spectrum similar to the conventional baryon-antibaryon annihilation spectrum in vacuum. However, this assumption does not hold for the nuggets in a colour superconducting phase where the lightest pseudo Goldstone mesons (the pions and Kaons) have masses in the 20 MeV range, in contrast with conventional pion mass of roughly 140 MeV. Thus, the decay of these light pseudo Goldstone bosons of the CS phase cannot produce highly energetic neutrinos in the 20-50 MeV energy range.

Local and Cooperative Jahn-Teller Effect and Resultant Magnetic Properties of M2AgF4 (M = Na-Cs) Phases.

The crystal structure, magnetic properties, heat capacity, and Raman spectra of double-perovskite M2AgF4 (M = K, K3/4Rb1/4, K1/2Rb1/2, K1/4Rb3/4, and Rb) phases have been examined, adding to the body of previous results for the M = Na, Cs derivatives. The results suggest that double-perovskite K2AgF4 adopts a disordered orthorhombic Bmab structure with an antiferrodistortive arrangement of the elongated and tilted [AgF6] octahedra rather than the structure with the ferrodistortive arrangement of compressed octahedra, as suggested previously (Mazej, Z.; Goreshnik, E.; Jagličić, Z.; Gaweł, B.; Łasocha, W.; Grzybowska, D.; Jaroń, T.; Kurzydłowski, D.; Malinowski, P. J.; Koźmiński, W.; Szydłowska, J.; Leszczyński, P. J.; Grochala, W. KAgF3, K2AgF4 and K3Ag2F7: important steps towards a layered antiferromagnetic fluoroargentate(II). CrystEngComm 2009, 11, 1702-1710). A re-examination of the previously collected single-crystal X-ray diffraction data confirms the current structure assignment, and it is also in agreement with recent theoretical calculations. High-field electron paramagnetic resonance spectra reaffirm the presence of elongated [AgF6] octahedra in the crystal structure of all M2AgF4 phases studied. The local structure of the M = K derivative is most complex, with regions of the sample that are quite orthorhombically distorted, whereas other regions more closely resemble the tetragonal phase. The mixed-cation K/Rb phases are also inhomogeneous, containing regions of the pure K compound and regions of another high-symmetry phase (likely tetragonal) of a mixed (Rb-richer) compound with unknown composition. The temperature-resolved phase diagram of all K/Rb phases has been established and positioned within the entire M = Na, K, Rb, Cs series.

Carbonation behavior of hydraulic and non-hydraulic calcium silicates: potential of utilizing low-lime calcium silicates in cement-based materials

This paper presents a study on the carbonation behaviors of hydraulic and non-hydraulic calcium silicate phases, including tricalcium silicate (3CaO·SiO2 or C3S), γ-dicalcium silicate (γ-2CaO·SiO2 or γ-C2S), β-dicalcium silicate (β-2CaO·SiO2 or β-C2S), rankinite (3CaO·2SiO2 or C3S2), and wollastonite (CaO·SiO2 or CS). These calcium silicate phases were subjected to carbonation reaction at different CO2 concentration and temperatures. Thermogravimetric analysis (TGA) tests were performed to quantify the amounts of carbonates formed during the carbonation reactions, which were eventually used to monitor the degree of reactions of the calcium silicate phases. Both hydraulic and non-hydraulic calcium silicates demonstrated higher reaction rate in case of carbonation reaction than that of the hydration reaction. Under specific carbonation scenario, non-hydraulic low-lime calcium silicates such as γ-C2S, C3S2 and CS were found to achieve a reaction rate close to that of C3S. Fourier transformed infrared (FTIR) spectroscopy and scanning electron microscope (SEM) tests were performed to characterize the carbonation reaction products of the calcium silicate phases. The FTIR spectra during the early stage of carbonation reaction showed formation of calcium silicate hydrate (C–S–H) from C3S, γ-C2S, β-C2S, and C3S2 phases with a similar degree of polymerization as that of the C–S–H that forms during the hydration reaction of C3S. However, upon further exposure to CO2, these C–S–H phases decompose and eventually converted to calcium-modified (Ca-modified) silica gel phase with higher degree of silicate polymerization. Contradictorily, CS phase started forming Ca-modified silica gel phase even at the early stage of carbonation reaction. This paper also revealed the stoichiometry of the Ca-modified silica gel that formed during the carbonation reaction of the calcium silicate phases using the SEM/energy dispersive spectroscopy (EDS) and TGA results.

First principles study of structural, electronic and magnetic properties of magnesium

We investigated the structural, electronic, and magnetic properties of Mg, in the CS (simple cubic), NiAs (Nickel arsenide), FCC (rock-salt), R (Rhombohedral), Diamond and WZ (wurtzite) phases. Calculations were performed using the first-principles pseudo-potential method within the framework of spin-density functional theory (DFT).