Electrocatalysis in the nickeltitanium system
About: This article is published in Energy Conversion.The article was published on 1970-11-01. It has received 99 citations till now.
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TL;DR: In this paper, the authors review available experimental information on the existence, thermodynamic stability and physical properties of hydrides formed by the absorption of hydrogen gas in intermetallic compounds of two transition metals.
Abstract: The authors review available experimental information on the existence, thermodynamic stability and physical properties of hydrides formed by the absorption of hydrogen gas in intermetallic compounds of two transition metals. The emphasis is on stability. It is shown that empirical models for the stability of ternary hydrides can be reconciled with ideas based on the results of band structure calculations of (binary) metallic hydrides. It is concluded that metallic hydrides can be looked upon as alloys of metallic hydrogen. In addition to the thermodynamic properties of ternary metallic hydrides the authors discuss experimental information on electronic properties (magnetic, super-conductivity, band structure features) and on crystallographic and metallurgical properties (neutron scattering, nuclear and electron spin resonance, Mossbauer spectroscopy, diffusion). Applications are briefly reviewed.
348 citations
TL;DR: In this article, the authors highlight the operating principles and advances made in these battery systems during the recent years and highlight significant improvements have been made in the Ni-MH batteries which are slowly capturing the market occupied by the ubiquitous Ni-Cd batteries.
325 citations
TL;DR: In this article, a review of intermetallic compounds used for energy relevant electrocatalysis is presented, which is structured by the reactions in scope, which are the hydrogen evolution reaction (HER), electrochemical carbondioxide reduction reaction (eCO2RR), oxygen reduction reaction, hydrogen oxidation reaction (HOR), as well as the oxidation reactions of formic acid (FAOR), methanol (MOR), and ethanol (EtOR).
Abstract: Structurally ordered intermetallic compounds possess unique chemical and physical properties, making them an interesting class of materials for application in electrocatalytic reactions. This Review comprises the work on intermetallic compounds used for energy relevant electrocatalysis and is structured by the reactions in scope, which are the hydrogen evolution reaction (HER), electrochemical carbondioxide reduction reaction (eCO2RR), oxygen reduction reaction (ORR), hydrogen oxidation reaction (HOR) as well as the oxidation reactions of formic acid (FAOR), methanol (MOR), and ethanol (EtOR). Optimization pathways for electrocatalysts, based on the adjustability of the intermetallic materials, are highlighted, and experimental data are provided in a comparative manner, to provide an overview, foundation, and reference for further development.
227 citations
TL;DR: In this paper, the authors present some recent results on the electrochemical behavior of metal hydride batteries and the mechanisms of the hydrogen evolution reaction (h.r.) taking place.
216 citations
TL;DR: In this review article, the fundamentals of electrochemical reactions involving metal hydrides are explained, followed by a report of recent progress in hydrogen storage alloys for electrochemical applications.
Abstract: In this review article, the fundamentals of electrochemical reactions involving metal hydrides are explained, followed by a report of recent progress in hydrogen storage alloys for electrochemical applications. The status of various alloy systems, including AB₅, AB₂, A₂B₇-type, Ti-Ni-based, Mg-Ni-based, BCC, and Zr-Ni-based metal hydride alloys, for their most important electrochemical application, the nickel metal hydride battery, is summarized. Other electrochemical applications, such as Ni-hydrogen, fuel cell, Li-ion battery, air-metal hydride, and hybrid battery systems, also have been mentioned.
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TL;DR: In this article, it was shown that the number of covalent bonds resonating among the available positions about an atom (the metallic valence of the atom) increases from one to nearly six (5.78) in the sequence K, Ca, Sc, Ti, V, Cr in the first long period of the periodic table, remains nearly constant from Cr to Ni, and begins to decrease with Cu.
Abstract: The problem of the nature of the interatomic farces in the elementary metals and in intermetallic compounds and other alloys continues to be puzzling, despite the clarification of some questions which has been provided by quantum mechanical considerations. It has been my opinion, contrary to that of other investigator that the metallic bond is very closely related to the covalent (shared-electron-pair) bond, and that each atom in a metal may be considered as forming covalent bonds with neighboring atoms, the covalent bonds resonating among the available interatomic positions. It was shown in the first paper of this series that the number of covalent bonds resonating among the available positions about an atom (the metallic valence of the atom) increases from one to nearly six (5.78) in the sequence K, Ca, Sc, Ti, V, Cr in the first long period of the periodic table, remains nearly constant from Cr to Ni, and begins to decrease with Cu. This concept, which is substantiated by the magnetic properties of the metals and their alloys, provides a qualitative explanation of many properties of the transition metals (including those of the palladium and platinum groups), such as characteristic temperature (heat capacity at low temperatures), hardness, compressibility, coefficient of thermal expansion, and the general trend of interatomic distances. It will be shown in the following pages that it also permits the formulation of a system of atomic radii which can be used for the calculation of interatomic distances in metals and intermetallic compounds and for the interpretation of observed interatomic distances in terms of the electronic structure of the crystals. These atomic radii (which may be called metallic radii) are found, as expected, to show an intimate relation to the covalent radii of the atoms-a relation which, in its general nature, permitted Goldschmidt over twenty years ago to use data taken from both metals and ordinary covalent crystals in formulating a table of atomic radii, and which has been recognized3 as providing very strong support for the concept that metallic bonds are essentially resonating covalent bonds.
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120 citations
TL;DR: In this article, the transition metals and their alloys were discussed and discussed in terms of transition metal alloys and transition metal transition alloys, and the transition metal and its alloys.
Abstract: (1954). The transition metals and their alloys. Advances in Physics: Vol. 3, No. 10, pp. 149-242.
99 citations
TL;DR: In this article, the iso-enthalpy diagram has been drawn, and some information on the phase diagram has aiso been obtained from the heat-of-formation curves as well as from x-ray analysis.
Abstract: The heats of formation of 49 ternary and 27 binaryalloys in the nickel + titanium + aluminum stength from the component metals have been determined directly by means of a calorimeter described previously. From the results the isoenthalpy diagram has been drawn, and some information on the phase diagram has aiso been obtained from the heat-of-formation curves as well as from x-ray analysis. (auth)
98 citations