References of "Boschini, Frédéric"
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See detailHydrothermal self-assembly of sodium manganese iron phosphate particles: Growth mechanism and electrochemical performance in lithium-ion battery
Karegeya, claude; Mahmoud, Abdelfattah ULiege; Vertruyen, Bénédicte ULiege et al

in Solid State Ionics (2017), 312

Na2Mn1.5Fe1.5(PO4)3 (NMFP) dandelion sphere-like particles were successfully synthesized via a hydrothermal route without addition of any templates or surfactants (laboratory and pilot scales). The ... [more ▼]

Na2Mn1.5Fe1.5(PO4)3 (NMFP) dandelion sphere-like particles were successfully synthesized via a hydrothermal route without addition of any templates or surfactants (laboratory and pilot scales). The hydrothermal reactor (pilot scale) is equipped with stirrer for continuous agitation of reagents during the reaction. The obtained materials were characterized by X-ray diffraction, Mössbauer spectroscopy and Scanning electron microscopy. Results show that Na2Mn1.5Fe1.5(PO4)3 samples obtained from the reaction performed at laboratory scale have hierarchical dandelion sphere-like morphology and the dandelions consist of micro-/nano-rods. On the other hand, we obtained the self-assembly nano-rods morphology for the particles prepared using hydrothermal reactor. On the basis of the experimental results, a growth mechanism of Na2Mn1.5Fe1.5(PO4)3 self-assembly and dandelion sphere-like particles was proposed. Temperature and time of hydrothermal reaction are found to be crucial parameters in controlling the growth of Na2Mn1.5Fe1.5(PO4)3 particles. In addition, investigation of the effect of continuous stirring during the hydrothermal reaction shows that the reaction time can be optimized to obtain Na2Mn1.5Fe1.5(PO4)3 with small particles size. The influence of stirring on the NMFP morphology has been clearly evidenced. Indeed, the stirring leads to homogeneous particles. Cycling studies have shown that the synthesized Na2Mn1.5Fe1.5(PO4)3 dandelions materials exhibit specific discharge capacities of about 62 and 57 mAh g−1 equivalent to about 1.2 and 1.05 lithium ions de-intercalated at C/15 and C/10 current density respectively. [less ▲]

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See detailElectrode materials for Li/Na-ion batteries: Improving electrochemical performance through carbon addition during synthesis
Mahmoud, Abdelfattah ULiege; Karegeya, Claude; Eshraghi, Nicolas ULiege et al

Poster (2017, October 12)

Lithium-ion batteries have been widely applied as a power source for portable and stationary energy storage systems. Na-ion batteries are considered to be an alternative to Li-ion batteries owing to the ... [more ▼]

Lithium-ion batteries have been widely applied as a power source for portable and stationary energy storage systems. Na-ion batteries are considered to be an alternative to Li-ion batteries owing to the natural abundance of sodium. New electrode materials are required to increase the energy density of Li/Na-ion batteries. In this study, we show that the addition of the carbon sources during the synthesis leads to control the particles size and morphology and improve their conductivity properties that enhance the electrochemical performance [1-5]. In order to study the effect of the carbon on the structural, morphological and electrochemical properties of the prepared materials by a spray-drying [1-3] or hydrothermal methods [4, 5]. The crystal and local structure were analyzed by XRD and Mössbauer spectroscopy. The morphological properties were characterized by SEM and TEM. The carbon content was determined by TG/TDA and carbon analyzer. The electrochemical properties were studied by impedance spectroscopy and galvanostatic cycling in lithium cells. Finally, the reaction mechanism during cycling was investigated using operando XRD technique. 1- A. Mahmoud, S. Caes, M. Brisbois, R.P. Hermann, L. Berardo, A. Schrijnemakers, C. Malherbe, G. Eppe, R. Cloots, B. Vertruyen, F. Boschini, Spray-drying as a tool to disperse conductive carbon inside Na2FePO4F particles by addition of carbon black or carbon nanotubes to the precursor solution, J. Solid State Electrochem. (2017) 1–10. 2- N. Eshraghi, S. Caes, A. Mahmoud, R. Cloots, B. Vertruyen, F. Boschini, Sodium vanadium (III) fluorophosphate/carbon nanotubes composite (NVPF/CNT) prepared by spray-drying: good electrochemical performance thanks to well-dispersed CNT network within NVPF particles, Electrochim. Acta, 228 (2017) 319–324. 3- M. Brisbois, S. Caes, M-T. Sougrati, B. Vertruyen, A. Schrijnemakers, R. Cloots, N. Eshraghi, R-P. Hermann, A. Mahmoud, F. Boschini, Na2FePO4 F/multi-walled carbon nanotubes for lithium-ion batteries: Operando Mössbauer study of spray-dried composites, Solar Energy Materials & Solar Cells 148 (2016) 67-72. 4- C. Karegeya, A. Mahmoud, B. Vertruyen, F. Hatert, R.P. Hermann, R. Cloots, F. Boschini, One-step hydrothermal synthesis and electrochemical performance of sodium-manganese-iron phosphate as cathode material for Li-ion batteries, J. Solid State Chem.253 (2017) 389–397. 5- C. Karegeya, A. Mahmoud, R. Cloots, B. Vertruyen, F. Boschini, Hydrothermal synthesis in presence of carbon black: Particle-size reduction of iron hydroxyl phosphate hydrate for Li-ion battery, Electrochimica Acta. Electrochim. Acta 250 (2017) 49–58. [less ▲]

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See detailA SPRAY DRYING METHOD FOR THE PREPARATION OF Na2FePO4F/CB AND Na2FePO4F/CNT COMPOSITES CATHODE FOR LITHIUM-ION BATTERIES
Mahmoud, Abdelfattah ULiege; Berardo, Loris ULiege; Brisbois, Magali et al

Poster (2017, September 18)

Fluorophosphates are considered among the most interesting series of cathode material for Li/Na-ion batteries1. Na2FePO4F (space group Pbcn), with its layered structure and two-dimensional pathways for ... [more ▼]

Fluorophosphates are considered among the most interesting series of cathode material for Li/Na-ion batteries1. Na2FePO4F (space group Pbcn), with its layered structure and two-dimensional pathways for facile Na+/Li+ transport, exhibits minimal structural changes upon reduction/oxidation. The average working voltage is 3.3 V vs. Li/Li+. Intercalation/deintercalation results in a volume change of only 3.7%. However, one of the key drawbacks of Na2FePO4F electrodes is their low intrinsic electronic conductivity. In order to study the effect of the carbon black and carbon nanotubes on the electrochemical performance of Na2FePO4F cathode material for lithium-ion batteries, Na2FePO4F, Na2FePO4F/CB and Na2FePO4F/CNT were prepared by a spray-drying method with different ratios of CB and CNT (10 and 20%). The crystal and local structure were analyzed by XRD and Mössbauer spectroscopy. The electrochemical properties were studied by galvanostatic cycling in lithium cells. The electrochemical performance is markedly better in the case of Na2FePO4F/CNT (20 wt%), with specific capacities of about 100 mAh/g (Na2FePO4F/CNT) at C/4 rate2 vs. 50 mAh/g for Na2FePO4F/CB. The characterization of Na2FePO4F/CB particles by electron microscopy revealed a carbon-poor surface and a good carbon dispersion for Na2FePO4F/CNT particles attributed to better diffusion of carbon nanotubes in the droplets during drying. References : 1-N. Eshraghi, S. Caes, A. Mahmoud, R. Cloots, B. Vertruyen, F. Boschini, Electrochim. Acta, 228 (2017) 319–324. 2-M. Brisbois, S. Caes, M-T. Sougrati, B. Vertruyen, A. Schrijnemakers, R. Cloots, N. Eshraghi, R-P. Hermann, A. Mahmoud, F. Boschini, Solar Energy Materials & Solar Cells 148 (2015) 67-72. [less ▲]

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See detailComparison of the electrochemical performance of Li4Ti5O12 spinel as negative electrodes for lithium-ion batteries prepared by sol gel and spray drying methods
Mahmoud, Abdelfattah ULiege; Piffet, Caroline ULiege; Berardo, Loris ULiege et al

Poster (2017, September 05)

Energy is considered as the lifeblood of modern society. Rechargeable batteries are the most promising to meet the human needs concerning the energy storage thanks their high energy density and high ... [more ▼]

Energy is considered as the lifeblood of modern society. Rechargeable batteries are the most promising to meet the human needs concerning the energy storage thanks their high energy density and high energy efficiency. Most difficult challenges of the development of promising rechargeable batteries concern the electrode materials. Li4Ti5O12 (LTO) is one the most promising anode materials for Li-ion batteries, as it demonstrates very stable cycling stability and excellent safety. Its high operating potential (~1.5 V) allows to avoid the formation of SEI during the first cycle. The three-dimensional structure offers LTO excellent reversibility due to the near zero volume strain during the Li+ ion intercalation and deintercalation cycling. The main objective of this study on LTO samples was to evidence the effect of synthesis method and thermal conditions on their structural, morphological and electrochemical properties [1, 2]. The results demonstrate the strong influence of the synthesis route (Sol-Gel and spray-drying methods) and the thermal treatment on the capacity, cyclability and rate capability of the LTO spinel in Li-half-cell and Li-ion full-cell (see Figure 1). References [1] A. Mahmoud, J. M. Amarilla, K. Lasri, I. Saadoune, Electrochim. Acta 93 (2013) 163-172. [2] A. Mahmoud, J. M. Amarilla, I. Saadoune, Electrochim. Acta 163 (2015) 213-222. [less ▲]

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See detailUp-scalable spray-drying synthesis of Na2Ti3O7
Piffet, Caroline ULiege; Vertruyen, Bénédicte ULiege; Mahmoud, Abdelfattah ULiege et al

Poster (2017, September)

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See detailPreparation and characterization of Silicon-carbon composite powders using recycled Silicon from solar cells as anode material in Li-ion batteries
Eshraghi, Nicolas ULiege; Mahmoud, Abdelfattah ULiege; Berardo, Loris ULiege et al

Poster (2017, September)

Currently, silicon (Si) coming from the recycling of solar cells is a non-valued fraction. The principal aim of this work is the development of silicon recovered during the dismantling of solar panels as ... [more ▼]

Currently, silicon (Si) coming from the recycling of solar cells is a non-valued fraction. The principal aim of this work is the development of silicon recovered during the dismantling of solar panels as electrode material for Li-ion batteries. The main technological challenge associated with the use of silicon in this type of application is to control the volume expansion during charge/discharge cycles. This drawback could be avoided through the formation of Silicon/carbon composites in which the size of the silicon particles and their dispersion must be controlled. In this research, we develop a carbon matrix consisting of graphene or carbon nanotubes (CNT) that allow the incorporation of silicon particles coated with a carbon layer (Si@C/C). The process is divided in two main steps : I) the grinding of leached Si wafer pieces in order to extract pure Si powder and then a mixed aqueous suspension of this recycled Si and an organic carbon source (Acetic acid, Ascorbic acid or Lactose) is spray-dried followed by heat treatment to generate the coating of silicon particles with carbon (Si@C). Then, II) aqueous suspension of Si@C and graphene/CNT is spray dried and calcined to obtain the final composite structure (Si@C/C). The morphology of composite materials is analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrochemical performance of Si@C/C composites are characterized by galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy (EIS). [less ▲]

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See detailRecycling of silicon used in solar cells to prepare silicon-carbon composite powders as anode material in li-ion batteries
Eshraghi, Nicolas ULiege; Mahmoud, Abdelfattah ULiege; Berardo, Loris ULiege et al

Poster (2017, September)

Currently, silicon (Si) coming from the recycling of solar cells is a non-valued fraction. The principal aim of this work is the development of silicon recovered during the dismantling of solar panels as ... [more ▼]

Currently, silicon (Si) coming from the recycling of solar cells is a non-valued fraction. The principal aim of this work is the development of silicon recovered during the dismantling of solar panels as an electrode material for lithium or sodium batteries. The main technological challenge associated with the use of silicon in this type of application is to control the volume expansion during charge/discharge cycles. This problem could be solved through the synthesis of Silicon/carbon composites in which the size of the silicon particles and their dispersion must be controlled [1–4]. We develop a carbon matrix consisting of graphene or carbon nanotubes (CNT) that allow the incorporation of silicon particles coated with a carbon layer (Si@C/C). The process is divided in two main steps. In the first step, Si wafer pieces are ground to prepare Si powder and then a mixed suspension of Si and an organic carbon source (Acetic acid, Ascorbic acid or Lactose) is spray-dried followed by heat treatment to generate the coverage of silicon particles with carbon (Si@C). In the second step, aqueous suspension of Si@C and graphene/CNT is spray dried and heat treated to obtain the final composite structure. The morphology of composite materials is analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrochemical performance of Si@C/C composites are characterized by galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy (EIS). [less ▲]

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See detailExperimental and theoretical investigation of SrFe12O19 nanopowder for permanent magnet application
Abraime, Brahim; Ait tamerd, Mohamed; Mahmoud, Abdelfattah ULiege et al

in Ceramics International (2017)

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000 °C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray ... [more ▼]

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000 °C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy (MS) and superconducting quantum interference device magnetometer (SQUID) techniques were used to characterize crystal structure, phase composition, morphology and magnetic properties. TGA gives T = 800 °C as beginning of suitable calcination. Hexaferrite structure of single phase is obtained according to XRD results for all samples with crystallite size between 28 nm and 35 nm. SEM images show the growth of grain size with increasing of annealing temperature. (BH)max is calculated based on SQUID results and shows an enhancement between T = 800 °C and T = 1000 °C of 25%. The magnetic properties observed at low temperature are explained and confirmed by ab-initio calculations [less ▲]

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See detailHydrothermal synthesis in presence of carbon black: Particle-size reduction of iron hydroxyl phosphate hydrate for Li-ion battery
Karegeya, Claude ULiege; Mahmoud, Abdelfattah ULiege; Cloots, Rudi ULiege et al

in Electrochimica Acta (2017), 250

Iron hydroxyl phosphate hydrate Fe1.19(PO4)(OH)0.57(H2O)0.43 (FPHH) was obtained by hydrothermal synthesis at 220 °C for 6 hours. Addition of carbon black to the solution before hydrothermal treatment led ... [more ▼]

Iron hydroxyl phosphate hydrate Fe1.19(PO4)(OH)0.57(H2O)0.43 (FPHH) was obtained by hydrothermal synthesis at 220 °C for 6 hours. Addition of carbon black to the solution before hydrothermal treatment led to a reduction of the FPHH particle size from ∼10 μm in the carbon-free compound to ∼300–500 nm in the FPHH-10%C and FPHH-20%C composite with a good dispersion of conducting carbon black. X-ray diffraction, 57Fe Mossbauer spectroscopy and a thermal decomposition study showed that the addition of carbon black did not interfere with the formation of the FPHH phase. Thanks to its favorable microstructural characteristics, the FPHH-10%C and FPHH-20%C material exhibited good performance as positive electrode for Li-ion battery, with high initial discharge capacities of 150, 128 and 112 mAh g−1 at 0.25C, 0.5C and 1C rates respectively and 99% capacity retention after 150 cycles at 2C. These results show that addition of solid carbon directly into the solution prior to hydrothermal treatment is a simple and effective way to reduce particle size and also to improve electronic conductivity by dispersing conductive carbon around the active material. This approach is easily transferable to other compounds prepared by hydrothermal synthesis, in order to control particle size while retaining the advantage of crystallization at low temperature. [less ▲]

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See detailSpray-drying as a tool to disperse conductive carbon inside Na2FePO4F particles by addition of carbon black or carbon nanotubes to the precursor solution
Mahmoud, Abdelfattah ULiege; Caes, Sebastien; Brisbois, Magali et al

in Journal of Solid State Electrochemistry (2017)

In this work, Na2FePO4F-carbon composite powders were prepared by spray-drying a solution of inorganic precursors with 10 and 20 wt% added carbon black (CB) or carbon nanotubes (CNTs). In order to compare ... [more ▼]

In this work, Na2FePO4F-carbon composite powders were prepared by spray-drying a solution of inorganic precursors with 10 and 20 wt% added carbon black (CB) or carbon nanotubes (CNTs). In order to compare the effect of CB and CNTwhen added to the precursor solutions, the structural, electrochemical, and morphological properties of the synthesized Na2FePO4F-xCB and Na2FePO4F-xCNT samples were systematically investigated. In both cases, X-ray diffraction shows that calcination at 600 °C in argon leads to the formation of Na2FePO4F as the major inorganic phase. 57Fe Mössbauer spectroscopy was used as complementary technique to probe the oxidation states, local environment, and identify the composition of the iron-containing phases. The electrochemical performance is markedly better in the case of Na2FePO4F-CNT (20 wt%), with specific capacities of about 100 mAh/g (Na2FePO4F-CNT) at C/4 rate vs. 50 mAh/g for Na2FePO4F-CB (20 wt%). SEM characterization of Na2FePO4F-CB particles revealed different particle morphologies for the Na2FePO4F-CNT and Na2FePO4F-CB powders. The carbon-poor surface observed for Na2FePO4FCB could be due to a slow diffusion of carbon in the droplets during drying. On the contrary, Na2FePO4F-CNT shows a better CNT dispersion inside and at the surface of the NFPF particles that improves the electrochemical performance. [less ▲]

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See detailHighly efficient doped nanocristalline TiO2 for water Treatment
Mahy, Julien ULiege; Léonard, Géraldine ULiege; Zubiaur, Anthony ULiege et al

Conference (2017, July 13)

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See detailOne-step hydrothermal synthesis and electrochemical performance of sodium-manganese-iron phosphate as cathode material for Li-ion batteries
Karegeya, Claude ULiege; Mahmoud, Abdelfattah ULiege; Vertruyen, Bénédicte ULiege et al

in Journal of Solid State Chemistry (2017), 253

The sodium-manganese-iron phosphate Na2Mn1.5Fe1.5(PO4)3 (NMFP) with alluaudite structure was obtained by a one-step hydrothermal synthesis route. The physical properties and structure of this material ... [more ▼]

The sodium-manganese-iron phosphate Na2Mn1.5Fe1.5(PO4)3 (NMFP) with alluaudite structure was obtained by a one-step hydrothermal synthesis route. The physical properties and structure of this material were obtained through XRD and Mössbauer analyses. X-ray diffraction Rietveld refinements confirm a cationic distribution of Na+ and presence of vacancies in A(2)’, Na+ and small amounts of Mn2+ in A(1), Mn2+ in M(1) , 0.5 Mn2+ and Fe cations (Mn2+,Fe2+ and Fe3+) in M(2), leading to the structural formula Na2Mn(Mn0.5Fe1.5)(PO4)3. The particles morphology was investigated by SEM. Several reactions with different hydrothermal reaction times were attempted to design a suitable synthesis protocol of NMFP compound. The time of reaction was varied from 6 to 48 hours at 220°C. The pure phase of NMFP particles was firstly obtained when the hydrothermal reaction of NMFP precursors mixture was maintained at 220°C for 6 hours. When the reaction time was increased from 6 to 12, 24 and 48 hours, the dandelion structure was destroyed in favor of NMFP micro-rods. The combination of NMFP (NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H) structure refinement and Mössbauer characterizations shows that the increase of the reaction time leads to the progressive increment of Fe(III) and the decrease of the crystal size. The electrochemical tests indicated that NMFP is a 3 V sodium intercalating cathode. The comparison of the discharge capacity evolution of studied NMFP electrode materials at C/5 current density shows different capacities of 48, 40, 34 and 34 mAhg-1 for NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H respectively. Interestingly, all samples show excellent capacity retention of about 99 % during 50 cycles. [less ▲]

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See detailExperimental design helps to optimize spray drying processes
Dellicour, Aline ULiege; Cloots, Rudi ULiege; Boschini, Frédéric ULiege

Poster (2017, June)

Experimental design is necessary to identify major experimental parameters linked to a process in order to optimize it and reduce costs. It also helps to reduce the number of experiments and analyze data ... [more ▼]

Experimental design is necessary to identify major experimental parameters linked to a process in order to optimize it and reduce costs. It also helps to reduce the number of experiments and analyze data statistically. This work aims to present some possibilities of how experimental design may be applied in the field of pharmaceutical powders production by spray drying. Depending on the application, powders need particular size, morphology, purity, crystallinity or polymorphism. All these characteristics may be influenced by process parameters and should be controlled to reach pharmaceutical requirements. [less ▲]

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See detailStructural and Magnetic Properties of Nanosized strontium Hexaferrite Powders: Experimental and theoretical investigation
Abraime, Brahim; Ait Tamerd, Mohamed; Mahmoud, Abdelfattah ULiege et al

Poster (2017, May 18)

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000°C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray ... [more ▼]

Strontium M-type hexagonal ferrites were synthesized at different calcination temperatures (800 °C, 1000°C and 1100 °C) using sol-gel autocombustion method. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy (MS) and superconducting quantum interference device magnetometer (SQUID) techniques were used to characterize crystal structure, phase composition, morphology and magnetic properties. TGA gives T=800 °C as beginning of suitable calcination. Hexaferrite structure of single phase is obtained according to XRD results for all samples with crystallite size between 28 nm and 35 nm. SEM images show the growth of grain size with increasing of annealing temperature. (BH)max is calculated based on SQUID results and shows an enhancement between T=800°C and T= 1000°C of 25%. The magnetic properties observed at low temperature are explained and confirmed by ab-initio calculations. [less ▲]

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See detailAn easy route to synthesis black phosphorus at low pressure and soft conditions
Tiouitchi, Ghassane; Hamedoun, Mohammed; El Kenz, Abdallah et al

Conference (2017, May 11)

Black phosphorus a promising candidate for large application, due to his variety of structural and physical properties, can be prepared by a very low-coast reaction route with high purity and ... [more ▼]

Black phosphorus a promising candidate for large application, due to his variety of structural and physical properties, can be prepared by a very low-coast reaction route with high purity and crystallinity. Black phosphorus is prepared from red phosphorus at 873K under reduced pressure using a simple and low cost catalytic system. The quality of crystal with lattice parameters a=3.31Å, b=10.48Å, c=4.37Å can be approved by a series of characterizations like scanning microscopy electron (SEM), energy dispersive spectrometry (EDX), Raman spectroscopy and powder X-rays. The new preparation method of black phosphorus represents an easy, effective and low cost approach to avoid complicated preparative setups, toxic catalysts, or “dirty” flux methods and is of general interest in elemental chemistry. [less ▲]

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See detailEnergy product and magnetic properties of strontium hexagonal ferrite: experimental and theoretical investigation
Abraime, Brahim; Ait Tamerd, Mohamed; Mahmoud, Abdelfattah ULiege et al

Conference (2017, May 10)

The interest toward hard magnetic materials increases in the last years. In order to have the best magnetic properties of these materials, researchers count on the efficiency of different synthesis ... [more ▼]

The interest toward hard magnetic materials increases in the last years. In order to have the best magnetic properties of these materials, researchers count on the efficiency of different synthesis methods. In permanent magnets application, ferrite materials possess a good place among the other magnet families. In permanent magnets field, the more important parameter that describes the magnetic strength of a magnet is the maximum energy product (BH)max. A strong permanent magnet has an important value of (BH)max. In this work, we will study the effect of annealing temperature on maximum energy product and other magnetic properties of Strontium hexaferrite SrFe12O19 synthesized using sol-gel autocombustion method, with different annealing temperatures, characterized using Thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy (MS) and superconducting quantum interference device magnetometer (SQUID). Ab initio calculation for magnetic properties is also performed in order to compare it with low temperature experimental results. [less ▲]

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See detailSpray Drying-­Assisted Synthesis of Na2FePO4F/CB and Na2FePO4F/CNT Composite Cathodes for Lithium Ion Battery
Mahmoud, Abdelfattah ULiege; Brisbois; Caes, sebastien et al

Conference (2017, May 08)

Fluorophosphates are considered among the most interesting series of cathode materials for Li/Na-ion batteries. Na2FePO4F, with layered structure and two-dimensional pathways for facile Na+/Li+ transport ... [more ▼]

Fluorophosphates are considered among the most interesting series of cathode materials for Li/Na-ion batteries. Na2FePO4F, with layered structure and two-dimensional pathways for facile Na+/Li+ transport [1], exhibits minimal structural changes (3.7%) upon reduction/oxidation. The average working voltage is 3.3 V versus Li+/Li. However, one of the key drawbacks of Na2FePO4F electrodes is their low intrinsic electronic conductivity. In this work, we report on the synthesis of Na2FePO4F by spray-drying, a technique which is easily scaled-up from the lab- to the industrial-scale and ensures a good homogeneity of all precursors. We are investigating the replacement of the grinding step by the addition of conductive carbon (carbon black and carbon nanotubes) to the solution containing the inorganic precursors of the Na2FePO4F phase in order to prepare Na2FePO4F/CB and Na2FePO4F/CNT with different ratios of CB and CNT (10 and 20%) and enhanced conductivity. The electrochemical performance shows that the addition of CNT improves remarkably the capacity of the NFPF electrode material thanks to better CNT dispersion inside and at the surface of the NFPF particles which enhances the electronic conductivity. Acknowledgements: The authors thank the Walloon Region for support under the “PE Plan Marshall 2.vert” program (BATWAL -1318146). A. Mahmoud is grateful to the Walloon region for a Beware Fellowship Academia 2015-1, RESIBAT n° 1510399. References [1] M. Brisbois, S. Caes, M-T. Sougrati, B. Vertruyen, A. Schrijnemakers, R. Cloots, N. Eshraghi, R-P. Hermann, A. Mahmoud, F. Boschini, Solar Energy Materials & Solar Cells 148 (2015) 11-19. [less ▲]

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See detailMagnetocaloric Properties of Zinc-Nickel Ferrites Around Room Temperature
El Maalam, Khadija; Fkhar, lahcen; Mohammed, Hamedoun et al

in Journal of Superconductivity and Novel Magnetism (2017)

In this paper, structural, magnetic, and magnetocaloric properties of zinc-doped nickel ferrite, Zn1−xNixFe2O4 (x = 0.3 and 0.4) were investigated. The samples were prepared using solid-state reaction. X ... [more ▼]

In this paper, structural, magnetic, and magnetocaloric properties of zinc-doped nickel ferrite, Zn1−xNixFe2O4 (x = 0.3 and 0.4) were investigated. The samples were prepared using solid-state reaction. X-ray diffraction (XRD) and magnetization measurements were performed to study crystallographic structure and magnetic properties. For a magnetic field changing from 0 to 5 T, the corresponding isothermal entropy change was found to be near 1.4 J/kg K for both samples. The decreasing of Ni content from x = 0.4 to 0.3, enables to shift the Curie temperature of Zn1−xNixFe2O4 from 450 K toward (325 K). As main results, it was found that the relative cooling power (RCP) could be significantly enhanced by changing Ni concentration in Zn1−xNixFe2O4 (505 J/kg (for x = 0.3) and 670 J/kg (for x = 0.4)), which is considered as a recommended parameter for a wide temperature range in magnetic refrigeration application. Our finding should inspire and open new ways for the enhancement of the magnetocaloric effect in spinel ferrite-based materials. [less ▲]

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