Assessment of near Pr2/3Sr1/3MnO3 oxide in magnetic cooling

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Magnetic properties of tin ferrites nanostructures doped with transition metal

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Efficient synthesis of pure bulk black phosphorus and high-quality exfoliation of phosphorene

Black phosphorus (BP) is the most promising material among the two-dimensional (2D) materials thanks to its layered structure and excellent semiconducting properties. Currently, bulk BP flakes are synthesized under high pressure and high-temperature conditions by chemical vapor deposition using high-cost Au-catalyst. Consequently, its applications as a crystalline semiconductor material in electronic devices are limited due to the low quality and purity of BP. In this work, we demonstrate an efficient and low-cost synthesis of highly crystalline BP by rapid low-pressure reaction of red phosphorus (RP) in the presence of a small amount of silver (Ag) in a vacuum-sealed quartz tube. The phosphorene layers were prepared by liquid-phase exfoliation (LPE) of high-quality BP crystals using various solvents such as isopropanol (IPA), N-methyl pyrrolidone (NMP) and Dimethylformamide (DMF). The resulting materials are investigated in detail including structural and morphological characterization along with thermal properties. We have obtained BP flakes which are uniform in size and morphology. The lateral sizes of the stable BP range from 50.7 nm after exfoliation in IPA to 204 nm after exfoliation in NMP. The most effective phosphorene layer separation was achieved by using the IPA solvent and centrifugation at 15000 rpm with a monolayer thickness of 0.5 - 0.6 nm. Phosphorene layer thicknesses of 1.0 - 2.0 nm and 1.7 – 2.6 nm are obtained when using NMP and DMF as solvents, respectively. We demonstrate the fine tuning of the optical bandgap by controlling the number of phosphorene layers

Coexistence of blocked, metamagnetic and canted ferrimagntic phases at high temperature in Co–Nd ferrite nanorods

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Magnetocaloric Properties of Zinc-Nickel Ferrites Around Room Temperature

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Effect of zinc concentration on the structural and magnetic properties of mixed Co–Zn ferrites nanoparticles synthesized by sol/gel method

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La cimenterie de Temara : besoins d’un nouveau gisement de calcaires (cas du gisement de l’oued Cherrat)

Au cours de ces dernières années, Asment Temara a eu recourt uniquement aux calcaires de l’ancienne carrière (Asment) pour la fabrication de son ciment, dont elle utilise environ 80 %. Cependant, avec l’évolution de l’exploitation de la carrière, la teneur moyenne en CaO a chuté, en outre l’usage du crible au niveau du concasseur primaire a conduit à une consommation accrue de calcaire. Cette situation a obligé Asment Temara de lancer une campagne de prospection pour la recherche d’une nouvelle carrière de calcaire dans la banlieue du site principal. Cette quête s’est montrée fructueuse par la découverte d’un nouveau gisement qui est celui de l’oued Cherrat. l’étude de ce gisement nous a permis de distinguer trois lithologies : calcaires francs, calcaires dolomitiques et faciès de transition (calcaires à interlits schisteux). Les données de sondages et la cartographie de surface nous ont permis d’estimer les réserves de ce gisement, qui sont de l’ordre de 22712213 millions de tonnes. Les mélanges réalisés au cours de ce travail nous amène à déduire qu’il s’avère nécessaire d’utiliser le calcaire de l’oued Cherrat pour prolonger la durée de vie de la carrière d’Asment, et de là, satisfaire les besoins du marché

From amorphous red phosphorus to black phosphorus crystal: An optimization, controllable and highest yield synthesis process

Understanding the growth mechanism of large crystals and high-quality of black phosphorus (BP) is a fundamental challenge to further study its physical properties. The BP was prepared from amorphous red phosphorus (RP), by short-way chemical vapor transport (CVT) reaction using the addition of small quantities of copper, tin, and tin(IV) iodide as reaction promoters. The method used in this present work is currently developed by our research laboratory for preparation of BP. In fact, a series of experiments was designed to understand and optimize the preparation conditions (the catalyst's choice (Cu), temperature, time, dimensions of quartz tube ...) of this surprisingly easy and effective method and to ensure a high BP conversion ratio (wt%) from RP with high purity, high crystallinity, and large size of orthorhombic BP (flakes size ∼1 cm), It’s the main goal of this work. The products recovered in the hot and cold zones of the tube are analyzed by X-ray diffraction (XRD) to give an idea of the role of mineralizers (Cu,Sn, and SnI4) allowing the synthesis of BP. Decomposition of reaction system (RP/Cu/Sn) with the tin(IV) iodide should lead to the formation of the condensed phases represented by Cu4SnP10,Sn4P3, CuSn,Cu2P7, SnI4 and P2O5could be detected at a hot zone of the tube. The characterizations of the prepared BP were carried out also using Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and Raman spectroscopy

Downsizing and coating effects on the electrochemical performance of Mn-doped iron fluorophosphate as cathode material for sodium-ion batteries

peer reviewedSodium Mn-doped iron fluorophosphate Na2Fe0·5Mn0·5PO4F is a potential positive electrode material for lithium-ion and sodium-ion batteries. This study outlines the synthesis of Na2Fe0·5Mn0·5PO4F powder through a simplified and more accessible production method. The X-rays diffraction (XRD) technique showed a pure phase with monoclinic symmetry (S.G. P21/n). The resulting uncoated material (labeled as NFeMPF) was ball-milled with dopamine hydrochloride (mentioned as dopamine hereafter) as a carbon source to enhance the specific surface and improve its electronic conductivity. Raman spectra confirmed the presence of residual carbon after the pyrolysis process. Thermogravimetric analysis (TGA) demonstrated the stability of Mn-doped iron fluorophosphate up to 1000 °C. Additionally, Mössbauer spectroscopy disclosed structural improvements in the material, indicating the reduction of all Fe(III) when coated with dopamine. The uncoated material discharge capacity when cycled against sodium exhibits reversible capacities of only 80, 67, and 38 mAh/g during the first cycle at C/20, C/16, and C/5, respectively. The coated NFeMPF@D delivered improved capacities of 272 and 202 mAh/g at C/20 and C/16, respectively. This highlights the considerable promise of the investigated phosphate-based electrode material as a cathode composite for the next generation of sodium-ion batteries

Synthesis and magnetic properties of tin spinel ferrites doped manganese

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