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1
Proposal Model for Programming Numerical Control Lathe Basis on the Concept by Features

N.Ben Yahia,Woo-Young Lee,B. Hadj Sassi 한국정밀공학회 2001 International Journal of Precision Engineering and Vol.2 No.3
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- 복사/대출신청
2
Unveiling the sodium intercalation properties in Na1.86□0.14Fe3(PO4)3

Essehli, R.,Ben Yahia, H.,Maher, K.,Sougrati, M.T.,Abouimrane, A.,Park, J.-B.,Sun, Y.-K.,Al-Maadeed, M.A.,Belharouak, I. Elsevier Sequoia 2016 Journal of Power Sources Vol. No.
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Abstract The new compound Na1.86□0.14Fe3(PO4)3 was successfully synthesized via hydrothermal synthesis and its crystal structure was determined using powder X-ray diffraction data. Na1.86Fe3(PO4)3 was also characterized by operando XRD and Mössbauer spectroscopy, cyclic voltammetry, and galvanostatic cycling. Na1.86Fe3(PO4)3 crystallizes with the alluaudite-type structure with the eight coordinated Na1 and Na2 sodium atoms located within the channels. The combination of the Rietveld- and Mössbauer-analyses confirms that the sodium vacancies in the Na1 site are linked to a partial oxidation of Fe2+ during synthesis. The electrochemical tests indicated that Na1.86Fe3(PO4)3 is a 3 V sodium intercalating cathode. At the current densities of 5, 10, and 20 mA g−1, the material delivers the specific capacities of 109, 97, and 80 mA h g−1, respectively. After 100 charge and discharge cycles, Na1.86Fe3(PO4)3 exhibited good sodium removal and uptake behavior although no optimizations of particle size, morphology, and carbon coating were performed. Highlights <UL> <LI> Na1.86□0.14Fe3(PO4)3 was synthesized via hydrothermal synthesis method. </LI> <LI> Na1.86□0.14Fe3(PO4)3 crystallizes with the Alluaudite-type structure. </LI> <LI> Operando in situ XRD and Mössbauer spectroscopy studies were carried on. </LI> <LI> The crystal structure of Na1.86□0.14Fe3(PO4)3 is stable during cycling. </LI> <LI> Na1.86□0.14Fe3(PO4)3 is a promising 3 V cathode material for sodium ion batteries. </LI> </UL> Graphical abstract Na1.86□0.14Fe3(PO4)3 was synthesized via hydrothermal synthesis method. Na1.86Fe3(PO4)3 crystallizes with the alluaudite-type structure. Na1.86Fe3(PO4)3 is a 3 V sodium intercalating cathode. At the current densities of 5, 10, and 20 mA g−1, the material delivers the specific capacities of 109, 97, and 80 mA h g−1, respectively. After 100 charge and discharge cycles, Na1.86Fe3(PO4)3 exhibited good sodium removal and uptake behavior with a stable crystal structure. [DISPLAY OMISSION]
3
Alluaudite Na2Co2Fe(PO4)3 as an electroactive material for sodium ion batteries

Essehli, R.,Belharouak, I.,Ben Yahia, H.,Maher, K.,Abouimrane, A.,Orayech, B.,Calder, S.,Zhou, X. L.,Zhou, Z.,Sun, Y-K. The Royal Society of Chemistry 2015 Dalton Transactions Vol.44 No.17
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The electroactive orthophosphate Na2Co2Fe(PO4)3 was synthesized using a solid state reaction. Its crystal structure was solved using the combination of powder X-ray- and neutron-diffraction data. This material crystallizes according to the alluaudite structure (S.G. C2/c). The structure consists of edge sharing [MO6] octahedra (M = Fe, Co) resulting in chains parallel to [−101]. These chains are linked together via the [PO4] tetrahedra to form two distinct tunnels in which sodium cations are located. The electrochemical properties of Na2Co2Fe(PO4)3 were evaluated by galvanostatic charge–discharge cycling. During the first discharge to 0.03 V, Na2Co2Fe(PO4)3 delivers a specific capacity of 604 mA h g−1. This capacity is equivalent to the reaction of more than seven sodium ions per formula unit. Hence, this is a strong indication of a conversion-type reaction with the formation of metallic Fe and Co. The subsequent charge and discharge involved the reaction of fewer Na ions as expected for a conversion reaction. When discharged to 0.9 V, the material intercalated only one Na+-ion leading to the formation of a new phase Na3Co2Fe(PO4)3. This phase could then be cycled reversibly with an average voltage of 3.6 V vs. Na+/Na and a capacity of 110 mA h g−1. This result is in good agreement with the theoretical capacity expected from the extraction/insertion of two sodium atoms in Na3Co2Fe(PO4)3. Graphic AbstractNa2Co2Fe(PO4)3 crystallizes with the alluaudite-type structure (S.G. C2/c) and plays a dual anode/cathode behavior in sodium ion batteries. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5dt00971e'>