Effect of substitutional elements on hydrogen absorption properties in Mm-based AB5 alloys
TL;DR: In this paper, the authors studied the hydrogen absorption isotherms for the CaCu5 hexagonal structured alloys MmNi3.4, Mm Ni3.8Al 0.368Mn0.5Fe0.4Co 0.333V0.333Al0.3Fe0,4Fe 0.5Co 0,5Fe 0,6Al 0,7Al 0 0,8Al0 0.4Fe0 0,4Co0.
About: This article is published in Journal of Alloys and Compounds.The article was published on 2004-01-28. It has received 48 citations till now. The article focuses on the topics: Hydrogen & Hydrogen storage.
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TL;DR: In this paper, a series of hydrogen storage Co-free AB3-type alloys are directly synthesized with vacuum mid-frequency melting method, and melted alloys were treated by low temperature short time heat annealing.
Abstract: In this paper, a series of hydrogen storage Co-free AB3-type alloys were directly synthesized with vacuum mid-frequency melting method, and melted alloys were treated by low temperature-short time heat annealing. XRD results indicate that the main phase of melted La0.7Mg0.3Ni3-xFex (x=0.0~0.4) alloys are LaMg2Ni9 and LaNi5 phase. After heat treatment, some LaMg2Ni9 phase transferred into LaNi3 phase because of the loss of Mg during the heat proceeding. The content of Fe element affects phase structure of alloys and led to different electrochemical properties. Heat treatment has positive effects on cycle stability of La0.7Mg0.3Ni3-xFex (x=0.0~0.4) alloys but could cause little reduction of discharge capacity of Fe substituted alloy. However, the discharge capacity of La0.7Mg0.3Ni2.8Fe0.2 alloy increased after heat treatment. The EIS results show that heat treatment has positive effect on H transfer within alloy, and Fe content is related to the diffusion coefficient of H atoms within alloys.
2 citations
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TL;DR: In this paper, the Johnson-Mehl-Avrami (JMA) model has been used to analyze the absorption kinetics of rhombohedral MmTM 3 (TM = Ni, Fe and Co) alloys.
2 citations
TL;DR: In this article, the effect of particle size, boron addition and PANI dispersion on the hydrogen absorption kinetics in MmNi3.5Al 0.5Fe0.5Co 0.1?40?bar has been studied and discussed.
Abstract: Pressure?composition (P?C) hydrogen absorption isotherms have been obtained for MmNi3.5Al0.5Fe0.5Co0.5+0.5?wt%?B and MmNi3.5Al0.5Fe0.5Co0.5 +25?wt% polyaniline (PANI) in the ranges 30?100??C and 0.1?40?bar using a high pressure Seiverts' apparatus. The phase structure and microstructure morphologies of as-prepared and ball-milled materials have been analysed by XRD and SEM respectively. The effect of particle size, boron addition and PANI dispersion on the hydrogen absorption kinetics in MmNi3.5Al0.5Fe0.5Co0.5 has been studied and discussed. The diffusion coefficient and activation energy of dissolved hydrogen in MmNi3.5Al0.5Fe0.5Co0.5, MmNi3.5Al0.5Fe0.5Co0.5+0.5?wt%?B and MmNi3.5Al0.5Fe0.5Co0.5+25?wt%?PANI have been obtained from the studies of hydrogen absorption kinetics using the first order rate equation and the results have been discussed.
2 citations
2 citations
TL;DR: In this paper, the authors investigated the absorption/desorption properties of MmNi 4.5 Cr 0.5− x Zr x alloys and found that the dissociation plateau pressure increased linearly with increasing cell volume V and the lattice parameter a.
1 citations
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TL;DR: A key to pharmaceutical and medicinal chemistry literature and training of literature chemists are discussed in the Advances series as mentioned in this paper, with the focus on the training of chemistry chemists, which is a subject of great interest to the literature chemist.
Abstract: NUMBERS 16 and 17 in the Advances series have made their appearance. The titles are: "A Key to Pharmaceutical and Medicinal Chemistry Literature" and "Training of literature Chemists." The first is a collection of papers presented before the Divisions of Chemical Literature and Medicinal Chemistry; the second consists of papers given before a joint meeting of the Divisions of Chemical Education and Chemical Literature. Glancing at the titles of subjects covered to date in the Advances series, it becomes evident that a substantial literature is being built by literature chemists, largely through the divisions in the AMERICAN CHEMICAL SOCIETY. Number 4, "Searching the Chemical Literature," has been reprinted several times and frequently is referred to as the "bible" of literature chemists. Number 10, "Literature Resources for Chemical Process Industries," is in much demand. Nomenclature is a subject of direct importance to the literature chemist, and Number 8, entitled "Chemical Nomenclature," and ...
3,188 citations
TL;DR: In this paper, the structural and electrochemical properties of the La0.7Mg0.3(Ni0.85Co0.15)x (x=3.15, 3.30), 3.65,3.50, and 3.80) hydrogen storage electrode alloys have been studied systematically.
146 citations
TL;DR: In this paper, the magnetic properties of the hydrides were determined and compared with the original compounds and it was shown that the magnetic moment per Fe atom is much larger in hydride phases.
89 citations
TL;DR: In this paper, the authors studied the hydrogen absorption-desorption characteristics of multicomponent alloys such as MmNi5−xAl(Mn)y−zMz and MnNi5 −xMnyM2.
Abstract: In order to reduce the large hysteresis effect in MmNi hydrides (Mm misch metal) we studied the hydrogen absorption-desorption characteristics of multicomponent alloys such as MmNi5−xAl(Mn)y−zMz and MmNi5−xAl(Mn)yM2 (M = Co, Cr, Cu, Nb, Ti, V, Zr; x = 0.3 − 0.5; y = 0.3 − 0.5; z = 0.05 − 0.1). The substitution or addition of the element M eliminates the large hysteresis effect that occurs during an absorption-desorption cycle. The hysteresis factor (equal to In( P a P d )) for MmNi4.7Al0.3M0.1 hydrides decreased for additives M in the following order: Zr > Co > Cr > Ti,V > Cu. Investigations of the effects of cycling showed that spalling occurred more rapidly for MmNi4.5Mn0.5 than for MmNi4.5Mn0.5Zr0.005 and MmNi4.5Mn0.5Zr0.1.
77 citations
TL;DR: The hydrogen absorption and desorption characteristics of mischmetal (Mm)-nickel-aluminum alloys were investigated in this paper, where the same hexagonal structure as LaNi5 and MmNi5 was found to react readily with hydrogen to form the hydrides MnNi4.5Al0.75 Al0.5A10.
Abstract: The hydrogen absorption and desorption characteristics of mischmetal (Mm)-nickel-aluminum alloys were investigated. MmNi5−xAlx (x = 0.25 −0.5) have been found to have the same hexagonal structure as LaNi5 and MmNi5, and they reacted readily with hydrogen to form the hydrides MmNi4.75 Al0.25H5.4, MmNi4.65Al0.35H 5.3H5.3 and MmNi4.5Al0.5H4.9 (hydrogen content: 1.3,1.2 and 1.2 wt.%, respectively) under 60 atm hydrogen pressure at room temperature. The dissociation pressures of these hydrides were dependent on the aluminum content (aluminum partially substitutes for nickel) and the value of log Pbecame lower than the value for MmNi5 hydride as x increased. The enthalpy change on hydride formation as determined from the dissociation isotherms for the MmNi4.5Al0.5-H system was − 5.5 kcal (mol H2)−1; this value was smaller than those for LaNi5 and MmNi5. The dissociation pressure at 30 °C was 3 atm and was nearly the same as that of LaNi5. The desorption rate of hydrogen for MmNi4.5Al0.5 was larger than those for LaNi5 and MmNi5) and a value of 2.1 – 4.3 kcal mol−1 was obtained for the apparent activation energy of hydrogen desorption. For MmNi4.5Al0.5 the hydrogen absorption-desorption cycle was repeated 30 times, but no variation in the hydrogen absorption-desorption capacity was observed. The hydride of MmNi4.5A10.5 proved to be suitable for use as a stationary hydrogen storage material.
66 citations