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This paper presents a study of the complex permittivity of n-type copper indium selenide semiconductor compound at low temperatures down to −175 °C. Alternating current with frequency varying between 20 Hz and 1 MHz is applied to the material in order to measure the dielectric constant ɛ′ and dielectric loss D = ɛ″/ɛ′. ɛ′ is found to decrease with temperature and frequency, whereas D decreases with frequency and increases with temperature. The experimental data of ɛ″ agree with the expression ε ″ = A ω m ω , T ${\varepsilon }^{{\prime\prime}}=A{\omega }^{m\left(\omega ,T\right)}$ , where the frequency exponent m(ω, T), calculated through the relation m ω , T = ∂ ⁡ ln ε ″ / ∂ ⁡ ln ⁡ ω T $m\left(\omega ,T\right)={\left.\left(\partial \mathrm{ln}{\varepsilon }^{{\prime\prime}}/\partial \mathrm{ln}\omega \right.\right)}_{T}$ , shows a frequency and temperature dependence. The data are analyzed in light of existing theoretical models.

In this study, we report the adsorption process of Congo Red (CR) dye by calcined Layered Double Hydroxide (ZAC) at 550°C. The urea hydrolysis method was applied to produce highly crystalline Zn2Al-LDH. Samples characterisation was carried out by X-ray diffraction (XRD), Thermogravimetric/differential thermal analysis (TG/DTA), and Fourier transform infrared spectroscopy (FTIR). The results show that the adsorption of CR on calcined ZnAl-LDH was accompanied by the reconstruction of the layered structure. The ZAC showed higher adsorption efficiency versus other adsorbent under investigation and optimum conditions of contact time, adsorbent dose, pH and temperature were found to be 50 min, 0.02 g, 7 and 318 K, respectively. Isotherm studies show that the Langmuir isotherm model was appropriate to describe the CR adsorption data compared with Freundlich and Temkin isotherm models, with a higher correlation coefficient (R2 > 0.99) and maximum adsorption capacity of 406.5 mg/g. The thermodynamic parameters revealed that the adsorption process was spontaneous, endothermic, and governed by chemisorption. To further facilitate the recovery process in CR adsorption, we test the feasibility of applying ZnAl-LDH and its calcined product at 550°C entrapped in alginate beads. Experimental results indicate that alginate-coated ZAC beads, which exhibited remarkable adsorption performance, were more stable and require less effort to pull and separate than the alginate/ZnAl-LDH composite beads.

LiNi0.5Mn1.5O4-based materials are considered an interesting choice to be used as positive electrode for Li-ion batteries. Several years ago, it has been shown that doping this material with an amount of Cr allowed an improvement of its electrochemical performances, particularly at high rate capability. Unfortunately, Cr is one of the most toxic elements, especially at the oxidation state + VI. To solve this drawback, we suggest using a little amount of Fe instead of Cr. In this work, we report the synthesis of a spinel structure material which general formula is LiFe2yNi0.5-yMn1.5-yO4 (y ≤ 0.1) through combustion method. Two annealing temperatures were used: one at 800 and the other at 900 °C. The morphological analysis revealed the samples prepared at 800 °C are nanometric, meanwhile the ones annealed at 900 °C showed two distribution of particle size: ∼200 nm and ∼ 600 nm. Regarding the electrochemical properties, at the slow discharge rate (1C), the samples prepared at 900 °C exhibit high capacity during their discharge and better capacity retention. The best electrochemical performances were delivered by the materials with 0.05 and 0.075 of Fe content, their capacities were around 130 mAh/g and their capacity retentions were in the order of 98.6% after 50 cycles. These excellent performances were confirmed by the tests made at high rate capabilities; LiFe0.1Ni0.45Mn1.45O4 (y = 0.5) material delivered a discharge capacity of 102mAh/g at 20C (complete discharge in 3 min) maintaining a capacity retention of 79.7%. These results correspond to 9.56 kW/kg of power density and 482.5 kWh/kg of energy density. To summarize, doping with iron allowed us to prepare environmentally friendly material to be used as a positive electrode for Li-ion batteries with excellent electrochemical performances, especially at high rate capability. This material is a good candidate to be used for applications which demands are high in density and in power densities.

Currently, the treatment of wastewater containing dye by the effective adsorbent attracts a great deal of interest. In this work, we report the removal of Congo Red (CR) dye from water using ZnAl-L...

Bioactive powders of the binary SiO2-CaO, ternary SiO2-CaO-P2O5 and quaternary systems SiO2-CaO-P2O5-Na2O/Mg2O were synthesized using a sol-gel route. The gels were converted into bioglasses powders by heat treatments at the temperature of 700°C. The resulting materials were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Environmental Scanning Electron Microscopy (ESEM) and in vitro bioactivity in acellular Simulated Body Fluid (SBF). The in vitro tests showed that the samples had good apatite-forming ability. Glasses doped with sodium and magnesium show good results in terms of bioactivity and mechanical properties. The results showed that the quaternary glass SiO2-CaO-P2O5-Na2O containing Na is the most bioactive, only 6 hours after its immersion in SBF; a layer of hydroxycarbonated apatite (HAC) was deposited on the glass and compressive strength of up to 233.08 MPa with a porosity of 11.02%, due to the presence of the Na2Ca2Si3O9 phase. Magnesium also affects bioactivity because it has improved from binary to ternary to quaternary doped with magnesium, bioactive from 12h of contact with the SBF.

Nanocrystalline titania was synthesized by a simple, innovative and eco-friendly gelation method by using biopolymers (polysaccharides). The effect of the gelling agent, such as carboxymethylcellulose (CMC) or alginate (Alg), and the drying routes (conventional drying at room temperature, or freeze-drying) on the properties and photocatalytic performances of nanostructured TiO 2 was examined. The crystallographic structures, and textural and morphological characteristics were investigated by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive spectrometry (ESEM-FEG-EDS), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS) and N 2 adsorption/desorption isotherms. The as-synthesized samples were fully crystallized and appeared to be highly phase-pure anatase or mixed titania polymorphs, and have a quasi-spherical shape with a particle size ranging from 10.34 to 18.07 nm. Phase-pure anatase was obtained by using alginate as the gelling agent, whereas CMC's gelation promotes mixed structures. The presence of rutile phase results in a lower bandgap value of 3.04 eV corresponding to 408 nm. Thus, the material absorption wavelength shifts slightly from the UV (190-380 nm) to visible region (380-750 nm). The drying process also affects TiO 2 properties. The lyophilization route improves the oxide's specific surface area, and also its photocatalytic properties verified during Orange G dye photodegradation study.

Cordierite based membranes were elaborated from a naturally Moroccan clay (Ghassoul) and algae as porosity agent (10 wt%). Specimens devoid of algae were also manufactured and used as reference samples (B1 & B2). To obtain the stoichiometry of cordierite, alumina and silica gel were added to the employed clay. After calcination at 600 °C, the mixture was heat treated according to two different thermal cycles. The first one consisted of a single thermal treatment at 1250 °C after the addition of the algae (BAL1). As for the second, two heat treatments were carried out at 1250 °C separated by the addition of the algae BAL2. Several techniques were used to characterize the cordierite membrane performances such as X-ray diffraction, thermal analysis, scanning electron microscope, Fourier-transform infrared spectroscopy and microscope impedance spectroscopy. Porosity and filtration suitability were assessed and correlated to the morphology. It has been proved that stevensite, dolomite and quartz were involved in the neoformation process and melt respectively. SEM examinations showed different features that exhibited different sized pores alongside with some melted zones. Algae addition contributed to the formation of pores in algae containing samples compared to the reference specimens. At room temperature, filtration tests were performed using textile effluent in order to reduce the turbidity, BOD and the chemical oxygen demand. The results showed that their percentages decreased by more than 60% after filtration. In addition, dielectric measurements revealed that the sintering process was effective beyond 1000 °C and it was accompanied with a low activation energy. Manufactured ceramic membranes are expected to have challenge application in the treatment of wastewater.

The mining industry is globally criticized for generating large amount of solid wastes often with a potential environmental impact. This study presents a feasible approach of recovering residual coal from coal mine waste rocks (CMWR) and reusing the derived tailings to produce ecofriendly fired bricks. The first step aims at the production of high grade anthracite coal concentrate using a physical treatment method which consists of consecutive stages of crushing, grinding and froth flotation. Coal (organic matter) was recovered in order to enhance the mechanical strength of bricks and to reduce the greenhouse gas (GHG) emissions during the firing process. The second step of the process consists of the mixture of the decarbonated tailings, called treated coal mine tailings (TCMT), with a small amount of water, pressed and fired at an optimal temperature of 1020 °C for the production of ecofriendly bricks at a laboratory scale. Fired bricks containing no other raw materials than CMWR or its derived TCMT have been produced showing in both cases very interesting ornamental looks. The study assessed the effects of removing coal from CMWR on the physical and technical properties of the derived fired bricks. The removal of coal from CMWR enhanced the quality of fired bricks by increasing its flexural strength and decreasing the open porosity and water absorption. In addition, the results show that this integrated process reduces the amount of GHG emissions by more than 70% and allows a sustainable production of fired bricks.

Nanocrystalline titania was synthesized by a simple, innovative and eco-friendly gelation method by using biopolymers (polysaccharides). The effect of the gelling agent, such as carboxymethylcellulose (CMC) or alginate (Alg), and the drying routes (conventional drying at room temperature, or freeze-drying) on the properties and photocatalytic performances of nanostructured TiO

This work aims to investigate the effect of sintering temperature and iron doping on the electrical conductivity of forsterite in the temperature range of 300–400 °C. For this purpose, olivine compositions (Mg2-xFexSiO4; x = 0, 0.05 and 0.1) were synthetized by sol-gel process and then characterized by different techniques. The obtained results indicate the successful formation of dense single phase olivine ceramics. It was also found that Fe inserted in forsterite lattice has both Fe (II) and Fe (III) oxidation states. Regarding the electrical conductivity, it turned out to be more sensitive to both investigation parameters, in contrast with the activation energy characterizing the diffusion of carriers charge responsible of electrical conductivity. The prepared samples were characterized by: XRD, SEM techniques and Raman, Mössbauer and impedance spectroscopies.

A correlation between the crystal structure, the ionic conductivity and the electrochemical performance in Lithium-ion batteries was established for a series of NASICON-type phosphates Li0.5M0.5Ti1.5Fe0.5(PO4)3 (M = Mn, Co, Mg). These electrode materials, where the M1 site contains both lithium and the divalent cation M, were prepared using a simple sol-gel process while controlling the pH and the final synthesis temperature. The three phosphates crystallize in the rhombohedral system (S.G. R-3c) with comparable unit cell parameters but with slight difference in the local distortion of the PO4 tetrahedra as confirmed by the Raman study. The ionic conductivities of the Li0.5M0.5Ti1.5Fe0.5(PO4)3 materials were measured at different temperatures using a wide range of frequencies. Mn-based phosphate shows the best features for application as electrode material for Li-ion batteries in term of the conductivity at room temperature and the activation energy of Li+ conduction process. The initial discharge capacity of 100 mAh.g − 1 was obtained for the Mg-based phosphate, 104.3 mAh.g − 1 for the Co-based material while the Mn-based material delivers the best first discharge capacity of 125.3 mAh.g − 1 with the lowest polarization in relation with its better conduction properties. This result was also confirmed by the rate capability tests where Mn-based phosphate shows enhanced electrochemical performance even at fast rate of 5C.

In the present work, the magnetocaloric effect of La1-xNaxMn1-yFeyO3 (x = 0.1, 0.2 and y = 0, 0.1) was investigated using magnetic characterization data. The X-ray diffraction confirms that all samples synthesized by flash combustion and calcined at 1000 °C have been crystallized in a rhombohedral structure with an R 3 ¯ c space group. According to the magnetization versus temperature results, LaMnO3 is a ferromagnetic material with a Curie temperature TC = 95 K. The substitution of the rare earth La by alkali magnetic metal Na leads to an increase of TC to 265 and 330 K accompanied with large magnetic entropy change / - Δ S M max / of 2.88 and 4.88 J.Kg-1K−1 for x = 0.1, 0.2, respectively. The addition of 10% of Fe in La1-xNaxMn1-yFeyO3 decreases the Curie temperature and the magnetic entropy change, while, the relative cooling efficiency increases. The Mossbauer spectrum recorded at room temperature represents a paramagnetic character of the manganites and proves the distribution of Fe3+ in the samples.

This paper provides an efficient alternative way to conserve natural clays and to reduce both fired bricks costs production and wastes amounts generation. It aims to substitute natural clay by treated calamine processing wastes (TCPMT) to manufacture value added fired bricks. Different mixes containing up to 40% of TCPMT were pressed, dried and fired at various temperatures: 900, 950, 1000 and 1050 °C. The fired bricks were characterized for their physical, mechanical, mineralogical, microstructural, environmental and durability properties. The results show that the increase of temperature allows the enhancement of mechanical strength, the reduction of water absorption due to the decrease of accessible pores amount and the enhancement of potential contaminants immobilization. The mechanical strength of bricks decreases with the addition of TCPMT due to the increased formation of pores and the apparition of some coarse grains which are considered as regions of weakness of the studied bricks. The leaching behavior of reference and selected optimum bricks, assessed according to a tank leaching test, shows that almost toxic elements; Pb, Zn, As, Cr, Mo, Ba, Cd and Cu are immobilized in the sintered bricks. Finally, the experimental approach outcomes show the possibility to produce bricks containing up to 30 wt% of TCPMT with the required engineering and environmental properties when fired at 1050 °C.

In this work, the recycling feasibility of treated calamine processing mine tailing (TCPMT) with glass wastes (GW) for the production of fired bricks is investigated. TCPMT was added into mixtures at a ratio of 0, 10, 20, 30, 40 and 50 % while glass waste was added separately for each formulation at ratios of 0, 5, 10 and 15 % of the dried mass of brick mixtures. The mixes of shale for brick (ShB), which consisted as the reference material, and both wastes were prepared, pressed, dried and fired at previously optimized temperature of 1020 °C. Physical, mechanical, environmental and durability properties of fired bricks were determined. The microstructural properties of fired bricks were investigated by scanning electron microscopy (SEM) and the total porosity was assessed according to ASTM standard. The results show that the increasing substitution proportion of ShB by TCPMT leads to an increase of the porosity and water absorption and to a decrease of flexural strength and density (lighter weight bricks). At the same time, the experiments showed that the addition of glass wastes into the mixtures enhances the mechanical properties of fired bricks. However, when more than 15 % of GW is used, a white scum constituted of a sodium sulphate appears at the fired brick exposed surface. Thus, fired light bricks with suitable physical and mechanical properties could be obtained from mixtures containing up to 30 % TCPMT and 10 % of GW.

International audience; Cordierite ceramic membranes were manufactured from natural clay, oxides and organic wastes as pore forming agents. Mixtures aforementioned materials with the pore-forming agents (up to 10 wt.%) were investigated in the range 1000-1200 degrees C using thermal analysis, X-ray diffraction, scanning electron microscopy, mercury porosimetry and filtration tests. Physical properties (density, water absorption and bending strength) were correlated to the processing factors (pore-forming agent addition, firing temperature and soaking time). The results showed that cordierite together with spinel, diopside and clinoenstatite neoformed. SEM analysis revealed heterogeneous aspects. The results of the response surface methodology showed that the variations of physical properties versus processing parameters were well described by the used polynomial model. The addition of pore forming agent and temperature were the most influential factors. Filtration tests were performed on the best performing sample. The results allowed to testify that these membranes could be used in waste water treatment. (C) 2017 The Ceramic Society of Japan and the Korean Ceramic Society. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.

The disposal of clayey quarry sludges generated during aggregate washing process, represents significant environmental impacts and additional economic burden for the aggregate production industry. In this paper three different quarry sludges were sintered and investigated at the range 900–1100 °C using X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Blends of the considered quarry sludges were studied and their physical properties (density, shrinkage, water absorption and compressive strength) were assessed. The effect of firing temperature on these properties was estimated and linked to the microstructure changes during heat treatment. The results revealed that anorthite, hematite, portlandite and lime were the neoformed phases. Breakdown products of clay minerals and carbonates contributed to the formation of some of these phases. The measured properties were strongly influenced by the firing temperature. Considering the measured technological properties, ceramic bodies with good mechanical performances (70 MPa) could be manufactured in the aforementioned conditions.

Ceramic membrane filters based on industrial by-products can be considered to be a valorization alternative of phosphate mine tailings, even more so if these ceramic membranes are used in the industrial wastewater treatment due to their good mechanical, chemical, and thermal resistance. The depollution of textile industry rejections with this method has not been studied in detail previously. In this work, ceramic membrane filters have been manufactured from natural clay and phosphate mine tailings (phosphate sludge). Blends of the abovementioned materials with a pore-forming agent (sawdust, up to 20 wt. %) were investigated in the range 900&ndash, 1100 &deg, C using thermal analysis, X-ray diffraction, scanning electron microscopy, and mercury porosimetry. Ceramic properties were measured as a function of firing temperature and sawdust addition. Filtration tests were carried out on samples with advantageous properties. The results showed that gehlenite together with diopside neoformed from lime decomposed carbonates and breakdown products of clay minerals, while calcium phosphate derived from partial decomposition of fluorapatite. Both quartz and fluorapatite resisted heating. The results of the experimental design showed that the variations of physical properties versus processing factors were well described by the polynomial model. Filtration results are quite interesting, allowing these membranes to be used in industrial effluent treatment.

International audience; In this work, the tribological behaviour of selective laser melting (SLM) processed hypereutectic Al-Si alloy is investigated by the ball on disc test with focus on the effect of silicon content (18 and 50 wt %). Different from the conventional casted sample, the SLM processed sample shows an ultra-fine microstructure with silicon size inferior to 5 μm. Indeed, the SLM processed hypereutectic Al-Si alloy illustrates a pseudo-eutectic microstructure consisted by supersaturated Al(Si) and primary silicon. Both the SLM processed Al-18Si and Al-50Si presents low wear rate about of 7.0 and 8.1◊10−4 mm3/(N◊m) respectively. Moreover, the wear mechanisms of conventional casted and SLM processed hypereutectic Al-Si alloys are compared and discussed.

In sedimentary phosphates mining operations, clayey layers are removed as mine wastes. The main objective of this paper was to investigate the feasibility to valorize these mine wastes as Lightweight aggregates (LWAs) by mixing them with organic wastes (sawdust and coffee grounds) which act as pore-forming agents. Thermal transformations and microstructural changes during heating were investigated using X-ray diffraction, thermal analysis, scanning electron microscope and Fourier-transform infrared spectroscopy. The bulk density, compressive strength and water absorption of LWAs were also determined. Neoformed mineral phases was characterized and correlated to the LWA microstructure. The results demonstrated that original aluminosilicated minerals, dolomite and part of quartz were involved in the mineralization process and melt abundance respectively. SEM observations displayed a tangled microstructure that results from merged particles and different pores sizes. The addition of pore-forming agent to clays waste enhanced the macro-pore formation process in comparison to the reference samples. LWAs with good performances (density 0.8–0.95 g/cm3 and compressive strength ∼77 MPa) were successfully manufactured by mixing 25 wt% of coffee grounds or sawdusts with clayey phosphate waste.

In the present study we report on the synthesis and crystal structure studies of NaCryFe1−yP2O7 sodium diphosphate solid solution (0 ≤ y ≤ 1). The X-ray diffraction shows that these compounds are isostructural with NaFeP2O7 and NaCrP2O7 (space group P21/c ( C 2 h 5 ) Z = 4). The Rietveld refinements based on the XRD patterns show the existence of a continuous solid solution over the whole composition range (0 ≤ y ≤ 1). A continuous evolution of the monoclinic unit cell parameters was obtained. The transition metal ions (Cr3+ and/or Fe3+) connect the diphosphate anions forming a three-dimensional network with cages filled by Na+ cations. IR and Raman spectra have been interpreted using factor group analysis. A small shift of the band frequencies is observed when Fe is substituted by Cr. The POP bridge angles are determined from Lazarev's relation and agree well with those deduced from the crystal structure refinement.

High amounts of mine wastes are continuously produced by the mining industry all over the world. Recycling possibility of some wastes in fired brick making has been investigated and showed promising results. However, little attention is given to the leaching behavior of mine wastes based fired bricks. The objective of this paper is to evaluate the geochemical behavior of fired bricks containing different types of coal wastes. The leachates were analyzed for their concentration of As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Zn and sulfates using different leaching tests; namely Tank Leaching tests (NEN 7375), Toxicity Characteristic Leaching Procedure (TCLP) and pH dependence test (EPA, 1313). The results showed that the release of constituents of potential interest was highly reduced after thermal treatment and were immobilized within the glassy matrix of the fired bricks. Moreover, it was also highlighted that the final pH of all fired samples changed and stabilized around 8-8.5 when the initial pH of leaching solution was in the range 2.5-11.5. The release of heavy metals and metalloids (As) tended to decrease with the increase of pH from acidic to alkaline solutions while Mo displayed a different trend.

International audience; The potential use of clay amended phosphate sludge in lightweight aggregates manufacturing was assessed. For this purpose, the microstructure of heated blends was examined with X-ray diffraction, thermal analysis and scanning electron microscope and impedance spectroscopy, and their physical properties were followed as a function of heating temperature, soaking time and clay content. For the latter study, the full factorial design was used. The results showed that phase neoformation involved the breakdowns of the clay minerals and lime of carbonates. Moreover, the sintering process was significant as the clay content exceeded 5 wt% and 900< T< 1000 degrees C. In such a condition, the sintering was chiefly controlled by melt. The results of the full factorial design showed that the increase of one of the processing factors affected positively water absorption, density and compressive strength. These effects were mainly linked to the conjugate formations of calcaluminosilicate and viscous phase. The results also pointed out that the effects of the interactions between the factors on the measured properties were almost negligible. By using the full factorial design, the optimum values of the physical properties were evaluated.

International audience; Blends of a naturally occurring clay (0-30 wt.%) and phosphate sludge were heated at different temperatures and times and their microstructures were investigated using impedance spectroscopy, dilatometry, X-ray diffraction and scanning electron microscope. The weights of the effects of the change of temperature, soaking time and clay addition on some physical ceramic properties (shrinkage, water absorption and compressive strength) were assessed. For the latter purpose, the response surface methodology was used. The results showed that the sintering process was effective between 750 and 1000 degrees C and occurred by melt flow. It was accompanied with low activation energy for ionic conduction (0.20-0.35 eV). Due to the quantitative formation of gehlenite (the unique neoformed phase), the ionic conduction regressed and the melt formation was limited. Also, it was shown that the effects of the experimental factors on physical properties of the blends were well described with the adopted polynomial models, and the weights of the effects of the factors followed the order: temperature > clay content > soaking time. The effects of the interactions between the factors on the properties studied were evaluated and discussed in relation to the microstructure change. (C) 2015 The Ceramic Society of Japan and the Korean Ceramic Society. Production and hosting by Elsevier B.V. All rights reserved.

Li-ion batteries have a huge potential for use in electrification of the transportation sector. The major challenge to be met is the limited energy storage capacity of the battery pack: both the amount of energy which can be stored within the space available in the vehicle (defining its range), and the aging of the individual battery cells (determining how long a whole pack can deliver sufficient energy and power to drive the vehicle). This thesis aims to increase our knowledge and understanding of structural changes induced by aging and usage of the Li-ion battery materials involved.Aging processes have been studied in commercial-size Li-ion cells with two different chemistries. LiFePO4/graphite cells were aged under different conditions, and thereafter examined at different points along the electrodes by post mortem characterisation using SEM, XPS, XRD and electrochemical characterization in half-cells. The results revealed large differences in degradation behaviour under different aging conditions and in different regions of the same cell. The aging of LiMn2O4-LiCoO2/Li4Ti5O12 cells was studied under two different aging conditions. Post mortem analysis revealed a high degree of Mn/Co mixing within individual particles of the LiMn2O4-LiCoO2 composite electrode.Structural changes induced by lithium insertion were studied in two negative electrode materials: in Li0.5Ni0.25TiOPO4 using in situ XRD, and in Ni0.5TiOPO4 using EXAFS, XANES and HAXPES. It was shown that Li0.5Ni0.25TiOPO4 lost most of its long-range-order during lithiation, and that both Ni and Ti were involved in the charge compensation mechanism during lithiation/delithiation of Ni0.5TiOPO4, with small clusters of metal-like Ni forming during lithiation.Finally, in situ XRD studies were also made of the reaction pathways to form LiFeSO4F from two sets of reactants: either FeSO4·H2O and LiF, or Li2SO4 and FeF2. During the heat treatment, Li2SO4 and FeF2 react to form FeSO4·H2O and LiF in a first step. In a second step LiFeSO4F is formed. This underlines the importance of the structural similarities between LiFeSO4F and FeSO4·H2O in the formation process of LiFeSO4F.

This work focuses on the building material used in the Saadian sugar refinery of Chichaoua (about 70 km southwest of Marrakesh). The study involved a classification of different types of rammed earth, followed by their mineralogical characterization based on optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). These studies are complemented by chemical investigations, X-ray fluorescence, and thermal analysis (DTA and TGA). The results demonstrate the use of two types of earth for the realisation of rammed earth, the first one non-plastic, -grained with added lime, the other one of low plasticity, and fine grained without addition of lime. Mechanical tests on site and in laboratory how at the first type of material exhibits great strength, exceeding the values known for rammed earth.

Ni0.5TiOPO4 oxyphosphate exhibits good electrochemical properties as an anode material in lithium ion batteries but suffers from its low conductivity. We present here the electrochemical performances of the synthesized Ni0.5TiOPO4/carbon composite by using sucrose as the carbon source. X-ray diffraction study confirms that this phosphate crystallizes in the monoclinic system (S.G. P21/c). The use of the Ni0.5TiOPO4/C composite in lithium batteries shows enhanced electrochemical performances compared with the uncoated material. Capacities up to 200 mAh g−1 could be reached during cycling of this electrode. Furthermore, an acceptable rate capability was obtained with very low capacity fading even at 0.5C rate. Nevertheless, a considerable irreversible capacity was evidenced during the first discharge. In situ synchrotron X-ray radiation was utilized to study the structural change during the first discharge in order to evidence the origin of this irreversible capacity. Lithium insertion during the first discharge induces an amorphization of the crystal structure of the parent material accompanied by an irreversible formation of a new phase.

Li 0.5 Ni 0.25 TiOPO 4 /C composite was synthesized by the co-precipitation method using polyethylene glycol as carbon source. X-ray diffraction study showed that the as-prepared material crystallizes in the monoclinic system (S.G. P 2 1 / c ). This 3D structure exhibits an open framework favourable to intercalation reactions. The morphology and the microstructure characterisation was performed by scanning electron microscopy (SEM). Small particles (∼1 μm) coated by carbon were observed. Raman study confirms the presence of carbon graphite in the Li 0.5 Ni 0.25 TiOPO 4 /C composite. Cyclic voltammetry (CV) and charge–discharge galvanostatic cycling were used to characterize its electrochemical properties. The Li 0.5 Ni 0.25 TiOPO 4 /C composite exhibits excellent electrochemical performances with good capacity retention for 50 cycles. Approximately 200 mAh/g could be reached at C , C /2, C /5 and C /20 rates in the 0.5–3 V potential range. These results clearly evidenced the positive effect of the carbon coating on the electrochemical properties of the studied phosphate.

Fluorine-doped indium oxide thin films, F-In2O3, prepared by the spray pyrolysis technique on glass substrates have been studied using cathodoluminescence spectroscopy, X-ray diffraction and spectrophotometry. These films, deposited at the optimal substrate temperature (Ts=450 °C), crystallize in a cubic structure with a preferential orientation along the (4 0 0) direction. For this temperature, the electrical resistivity is in the order of 6×10−3 Ω cm and the average optical transmission in the visible region is larger than 95%. At room temperature, the cathodoluminescence spectra of F-In2O3 present two emission peaks: blue indirect band gap peak at 410 nm and a red emission at 650 nm.

In this paper, we present the synthesis and characterizations of NaSICON-type ionic conducting ceramics of the general formula Na 1+ x M 1.775 Si x −0.9 P 3.9− x O 12 with 1.8 ≤ x ≤ 2.2 and M = Zr or Hf. The effect of the total substitution of zirconium by hafnium on electric properties has been studied. The various compositions were prepared by using the sol–gel method and the synthesized precursors were characterized by coupled DTA–TG. The oxides obtained after pyrolysis of the precursors were identified by X-ray diffraction. A sintering study by thermodilatometry permits to select the best thermal cycle adapted to our ceramics. Furthermore, the electric conductivity of the sintered ceramic samples was characterized by complex impedance spectroscopy. These results show that ceramics containing Zr synthesized by soft method, present a higher total conductivity than those obtained in literature (to be around 10 −4 S cm −1 ). The total substitution of Zr by Hf still improves this conductivity for some compositions.

This work concerns the results obtained during attempts of substitution of bismuth by antimony in superconductors Bi-cuprates family. The samples, prepared by dry way, from oxides and carbonates of the corresponding elements, are characterized by IR spectroscopy, X ray diffraction and differential thermal analysis. In every case, two domains appear: - for antimony concentration lower than 50 %, the main phase is isotype with the yellow phase Bi 2 Sr 3 CaO 7 . - for a concentration between 50% and 100%, we systematically obtain a perovskite isotype with Sr 1.45 Sb 0.55 O 3-y .

In this work, we present the synthesis and the characterization of ionic conducting ceramics of NaSICON-type (Natrium super ionic conductor). The properties of this ceramic make it suitable for use in electrochemical devices. These solid electrolytes can be used as sensors for application in the manufacturing of potentiometric gas sensors, for the detection of pollutant emissions and for environment control. The family of NaSICON that we studied has as a general formula Na{sub 2.8}Zr{sub 2-y}Si{sub 1.8-4y}P{sub 1.2+4y}O{sub 12} with 0=

International audience; Microstructure of expandable lightweight aggregates (LWAs), which was composed of phosphate waste (PW), cement kiln dust (CKD) and raw clay (RC) was investigated, and the effects of processing factors (temperature, waste content, soaking time) on their physical properties were quantified by using response surface methodology (RSM). The potential use of LWAs as a phosphorus source was assessed through the use of seeds of alfalfa. It was found that the main minerals of the waste, namely carbonates and fluorapatite, were involved in the formation of labradorite/anorthite and melt respectively. Stability of mullite- the main constituent of CKD- was sensitive to the melt content. The assemblage of the identified phases was discussed based on the CaO-SiO2-Al2O3 phase diagram. The results of RSM showed that the change of compressive strength, firing shrinkage and water absorption of LWAs versus processing factors was well described with a polynomial model and the weights of the effects of the factors increased in the following order: sintering temperature > waste content (in the case of PW-RC) > soaking time. On the other hand, it was found that due to the release of phosphorus by soil-embedded pellets, the growth of alfalfa plants improved, and the rate enhanced in this order: PW-RC > PW-CKD > PW-CKD-RC. The absorbed quantity of phosphorus (0.12%) was still lower than the common uptake amount. (C) 2016 Elsevier Ltd. All rights reserved.

The effect of the composition of two steels (B and 6MnCr5) on precipitation of undesirable phases (carbides, nitrides and carbonitrides) under thermochemical treatment (low-pressure or vacuum carbonitriding) is investigated. Metallographic and x-ray diffraction studies and thermodynamic computations are performed. BMI Fours Industriels, St. Quentin Fallavier, France

Synthesis by soft chemistry and characterization of hafnyle (IV) nitrate hydrate HfO(NO3)2, xH2O. This paper deals with the synthesis and characterization of hafnyle (IV) nitrate hydrate from HfCl4. The elaboration method is a soft chemistry one which allows to obtain a pure product. The nitrate was characterized by FTIR spectra, X ray diffraction and thermal analysis data (TDA-TGA). The degree of hydration was determined to be 2.

Bi 2 (Sr, Ln) 2 CuO z (Ln = Nd, Sm) single crystals were successfully grown by a self-flux method from stoichiometric and (Bi, Cu)-rich melts. Thermal analysis and thermogravimetry were used to determine stability and the melting sequence of Bi 2 (Sr, Ln) 2 CuO z phases in air. As-grown crystals of the ideal Bi 2 (Sr, Ln) 2 CuO z phase, of dimensions 1 x 0.5 x 0.03 mm 3 , exhibit superconducting behaviour with critical temperature T c = 21 K for the Bi 1.9 Sr 1.6 Nd 0.6 CuO z crystal and T c = 14 K for the Bi 1.8 Sr 1.6 Sm 0.6 CuO z crystal. The compositions of these crystals were homogeneous and close to the stoichiometric composition. We report on the growth of Bi 2 Sr 2-x Sm x CuO z single crystals of large dimensions 9 x 3 x 0.03 mm 3 using Bi 2 Sr 1.5 Sm 0.5 CuO z as precursor and Bi 2 CuO 4 as flux.

A new method was developed to elaborate (Bi,Pb)2Sr2CaCu2Ox (Pb-2212) single crystals. The new process makes use of a progressive increase of the oxygen chemical potential in gaseous phase at a constant temperature 875°C below the incongruent melting temperature (T=884°C) of the Pb-2212. The composition of this crystal is homogeneous and very close to the stoichiometric composition. Structure characterization of a single crystal was realized by measuring the (0 0 l) X-ray diffraction intensity. The superconducting temperature Tc(0)=90 K with a sharp transition width (10–90% level) between 5 and 10 K was determined from resistivity and DC susceptibility measurments.

BiMnO 3 synthesized at high pressure is a triclinically distorted perovskite and a ferromagnetic with T c =108 K. High-temperature X-ray diffraction analysis, thermal analysis, thermogravimetry, and magnetic measurements were used to determine stability and the melting sequence of BiMnO 3 phase in air. Structural phase transition from triclinic to tetragonal structure has been determined at 490°C in air for a polycrystalline BiMnO 3 perovskite. Two phases form immediately at the decomposition temperature of 600°C, namely Bi 2 O 3 and Bi 2 O 3 · 2Mn 2 O 3+ δ . The Bi 2 O 3 ·2Mn 2 O 3+ δ coexists with liquid up to at least 900°C.

TG-DTA and X-ray diffraction measurements at different temperatures and under different oxygen partial pressures were carried out on the species Bi1.6Pb0.4Sr2CuO6±x, Bi1.6Pb0.4Sr2CaCu2O8±y and Bi1.6Pb0.4Sr2Ca2Cu3O10±z to analyse the influence of the oxygen chemical potential on the phase transformations. A new phase was found at isobaric invariant equilibrium for 0.5≤\(P_{O_2 } \)/PTot≤1 at 884°C. This new phase presents a buffer effect towards oxygen exchange between superconducting oxides and the gas phase.