RETRACTED - High discharge capacities of Ti-based quasicrystal electrodes synthesized by mechanical alloying
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MRS Advances © 2018 Materials Research Society DOI: 10.1557/adv.2018.346
High discharge capacities of Ti-based quasicrystal electrodes synthesized by mechanical alloying DEDETEMO KIMILITA PATRICK 1,*, AKITO TAKASAKI2, ALICJA KLIMKOWICZ2 1
Global Course of Science and Engineering, Graduate School of Engineering and Science, Shibaura Institute of Technology, Toyosu, Koto-ku, Tokyo, 135-8548, Japan.
2
Department of Engineering Science and Mechanics, Shibaura Institute of Technology, Toyosu, Koto-ku, Tokyo, 135-8548, Japan.
*Dedetemo Kimilita Patrick [email protected] ABSTRACT
Ti-based quasicrystals are well known to store a high capacity of hydrogen exceeding the density of liquid hydrogen. This fact is due to that TiZrNi contain a large number of tetrahedral sites formed with Ti and Zr atoms that are chemical affinity with hydrogen. TiZrNi quasicrystal absorbs hydrogen up to host metal ratio (H/M) value near to 2.0. The disadvantage is due to the low equilibrium pressure. To solve this problem, we substituted Ti with a small amount of vanadium (V), with the nominal composition ( and synthesized by mechanical alloying. The subsequent annealing in vacuum conditions converted the amorphous into an icosahedral quasicrystal (I-phase) with face-centered cubic (FCC) -type crystal. As the results, we investigated the discharge capacity for both amorphous and quasicrystal electrodes using three electrodes system (working, reference and counter electrodes) at room temperature. The highest discharge capacities obtained were 81.45 mAh/g recorded for amorphous electrode and 318.4 mAh/g for quasicrystal whose compositions is at discharge current density of 15 mA/g. X-ray diffraction measurement was performed to provide the structural information on materials before and after hydrogenation. Microstructures of the materials were studied using an electron scanning microscope and the chemical compositions were confirmed using an EDX-analysis.
Introduction Quasicrystals are solids with long order, showing rotational symmetry patterns but no periodic arrangements of atoms [1]. Since their discovery, quasicrystals have been intensively studied and their properties have been found to be stable thermodynamically in many alloys such as Al-Li-Cu [2], Al-Cu-Fe [3], Ti-Zr-Ni [4] and Zn-Mg-Dy [5], by investigating stoichiometry variations around already known quasicrystals and approximants [6]. Nowadays, many interesting properties of quasicrystals are known, and attention has shifted from fundamental research to a possible application of quasicrystals in engineering [7]. Icosahedral (I) quasicrystalline phase which displays rotational symmetry of icosahedral point group is mostly dominated by local tetrahedral interstitial sites [8]. The dominance of polytetrahedral order makes I-phase of a potential use for hydrogen applications as energy storage or an anode material in batteries [8]. Ti-based quasicrystal alloys have attracted much attention because of high hydrogen capacity, low cost and thermodynamical stability [9]. The difficulty
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