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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.

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.

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.

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 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.

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.

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.

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.

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.

A new wet process has been used to directly prepare high- T c superconductor/silver composites from mixed precursors of the whole constituents including silver. In an aqueous solution of metal nitrates, either oxalic acid or potassium carbonate solutions have been introduced in order to coprecipitate oxalates or carbonates, respectively. The pyrolysis of the dried powder finally led to the desired final composite. Two series of high- T c superconducting oxide (HTS) have been studied; bismuth cuprates, Bi-2212 ( T c = 80–85 K) and YBa 2 Cu 3 O 7 (YBCO-123). The volume fractions (φ) of silver (expected in a final metallic form) ranged between 0 and 50%. The different phases produced during the synthesis were then characterized by coupled DTA-TGA analyses (differential thermal analysis and thermogravimetric analysis), X-ray diffraction, and Fourier transform infrared spectroscopy (FTIR). Measurements of levitation forces, magnetic susceptibility and electrical resistance at low temperature were carried out to control the final superconducting properties. In the case of YBa 2 Cu 3 O 7 some changes in structural parameters and physical properties are observed ( φ > 0.20).

DTA-DTG, X ray diffraction and metallographic measurements at different temperatures and partial oxygen pressure in the isoplethic cut “(Bi,Pb) 2 Sr 2 CuO x CaCuO 2 ”, were carried out to analyze the influence of partial constraint oxygen pressure on phase transformations. An isobaric invariant equilibrium has been found in the P o2 range 0.5–1. Supplementary phase appearing at invariant equilibrium is (Sr,Ca) 3 Cu 5 O y . That phase fixes oxygen and then the weight loss is stopped.

The oxygen exchange between the condensed phase(s) and the gas phase was studied as a function of temperature for superconducting phases of the system (Bi,Pb)-Sr-Ca-Cu-O.