Hydrogen absorption characteristics of the Zr-xHoxCo2 system in the pressure range 0–40 bar
TL;DR: In this paper, the C-15-type Laves phase structure of intermetallic compounds Zr 1-x Ho x Co 2 (x = 0.4, 0.6 and 0.8) was determined for the intermetall compounds with a temperature range 50-200 °C at pressures up to 40 bar.
About: This article is published in Journal of Alloys and Compounds.The article was published on 1993-01-29. It has received 36 citations till now. The article focuses on the topics: Hydrogen & Laves phase.
Citations
More filters
TL;DR: In this article, the enthalpies of binary transition-metal lanthanide Laves phases including ReCo 2, ReNi 2, ReFe 2 and ReRu 2 have been reviewed.
79 citations
TL;DR: In this article, the effect of non-stoichiometry on the hydrogen storage capacity of the alloys has been studied at 50 °C and the powder x-ray diffractograms of the alloy hydrides have been analyzed.
Abstract: Pressure–composition isotherms have been obtained for Ti0.1Zr0.9Mn0.9V0.1 Fe0.5Ni0.5, (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Ni0.5, Ti0.1Zr0.9(Mn0.9V0.1)1.1Fe0.5Ni0.5 and Ti0.1Zr0.9Mn0.9V0.1Fe0.55Ni0.55 having the C14 type hexagonal structure in the temperature and pressure ranges 30–100 °C and 0.1–50 bar using a pressure reduction method in order to find the effect of non-stoichiometry on hydrogen storage properties. The powder x-ray diffractograms of the alloys show the formation of C14 single phase; the lattice constants and unit cell volumes of these alloys have been calculated. Ti0.1Zr0.9(Mn0.9V0.1)1.1Fe0.5Ni0.5 has a hydrogen storage capacity of 3.5 hydrogen atoms/fu at 20 bar and room temperature. The dependences of the thermodynamics of the dissolved hydrogen in these alloy hydrides in the temperature range 30–100 °C on the hydrogen concentration have shown the existence of α, α+β and β phase regions as seen in the isotherms. The effect of non-stoichiometry on the kinetics of hydrogen absorption in these alloys has been studied at 50 °C. The powder x-ray diffractograms of the alloy hydrides show that these alloys do not undergo any structural change upon hydrogenation and that there is only a volume expansion of around 25%. The activation energy and diffusion coefficient of dissolved hydrogen in Ti0.1Zr0.9Mn0.9V0.1Fe0.5Ni0.5 have been calculated from the kinetics of hydrogen absorption measurements at different temperatures. The activation energy is Ea = 0.17 eV in the α+β phase region and Ea = 0.22 eV in the β phase region and the diffusion coefficient D = 2.7 × 10−11 cm2 s−1 in the β phase at 30 °C.
35 citations
TL;DR: In this article, powder X-ray diffraction patterns of Ti 0.1 Zr 0.5 Co 0.9 V 0.6 and Ti0.1 Fe 0.55 Co 0.5 have been obtained in order to study the effect of hydrogenation on the crystal structure.
33 citations
TL;DR: In this article, a range of (Ti0.65Zr0.35)1+xMnCr0.8Fe0.2 (x = 0, 0.075 and 0.1) C14 Laves phase AB2 type alloys were synthesized by levitation induction melting under an argon atmosphere.
25 citations
TL;DR: In this article, the existence of three different phase regions, α-phase, (α+β)-phase and β-phase have been identified from hydriding kinetic reactions and corresponding reaction rate constants.
24 citations
References
More filters
TL;DR: In this paper, a study of the change in hydrogen sorption properties caused by partially replacing La or Ni in LaNi5 by other metals is presented. But this study assumes that the more stable the original RNi5 compound, the weaker is the tendency to form a rNi5--hydride.
Abstract: Results are given of a study of the change in hydrogen sorption properties caused by partly replacing La or Ni in LaNi5 by other metals. Desorption isotherms at 40 deg C were measured for or Cu, and for La0.8R0.2Ni5, where represents Nd, Gd, Y, and Er, also Th and Zr. Equilibrium hydrogen pressures in the two-phase region can be explained qualitatively by assuming that the more stable the original RNi5 compound, the weaker is the tendency to form a RNi5--hydride, i.e., the higher the equilibrium pressure obtained for the hydride. This assumption which connects the stability of ternary hydrides with the heat of formation of the original compounds can also be formulated in a more quantitative way. This leads to a fair description of the experimental observations for the compounds having the CaCu5 type of structure.
428 citations
TL;DR: The formation and properties of the hydrides of the pseudobinary intermetallic compounds Zr(CoxM1−x)2 and Zr (FexM 1−x 2 ) were studied in this article.
Abstract: The formation and properties of the hydrides of the pseudobinary intermetallic compounds Zr(CoxM1−x)2 and Zr(FexM1−x)2 (M = V, Cr, Mn; 0
336 citations
01 Jan 1973
TL;DR: In this article, the authors measured the magnetic susceptibility x as a function of the hydrogen content n at various temperatures and obtained the limits nαmax and nβmin of the two-phase region of PdHn can only roughly estimate from the shape of the equilibrium isotherms pH2(n).
Abstract: The limits nαmax and nβmin of the two-phase region of PdHn can only roughly be estimated from the shape of the equilibrium isotherms pH2(n). Other methods applied so far do not yield more accurate results. More precise values can be obtained, however, from measurements of the magnetic susceptibility x as a function of the hydrogen content n at various temperatures.
Such x(n) isotherms have been measured at temperatures between 20 and 300°C and H2 pressures up to 140 atm (0 · n · 0.8), using samples of Pd wire (1 mm) and Pd foil (33 μm). In the homogeneity range isotherms for adsorption and desorption were identical, in the two-phase region, however, hysteresis was always observed. Here the desorption curve was taken as the equilibrium isotherm, and was applied to determine the values of nαmax and nβmin by extrapolation.
Measurements on Pd black in the same region of pressure and temperature showed a number of peculiarities, for instance smaller values of susceptibility and smaller hysteresis loops as compared with bulk Pd. These can be attributed to the large specific surface area of Pd black as well as to its strongly distorted lattice structure.
By means of the measurements on bulk Pd the position of the critical point of the palladium-hydrogen system could be redetermined with rather high precision: Tc = 291 ± 2°C; nc = 0.250 ± 0.005 mol H/mol Pd; Pc = 19.7 ± 0.2 atm H2.
The measurements on Pd-black yielded within the limits of error the same values for the critical temperature and the critical pressure, whereas the value of the H/Pd ratio, properly corrected, was found to be a bit higher, namely nc = 0.260 ± 0.005.
Die Grenzen nαmax und nβmin des Zweiphasengebietes von PdHn konnen aus der Form der Gleichgewichtsisothermen pH2(n) nur grob abgeschatzt werden. Andere bisher angewandte Methoden liefern keine genaueren Ergebnisse. Prazisere Werte konnen dagegen erhalten werden aus Messungen der magnetischen Suszeptibilitat x als Funktion des Wasserstoff-Gehaltes n bei verschiedenen Temperaturen.
Solche x(n)-Isothermen sind im Temperaturbereich 20 bis 300°C und mit H2-Drucken bis zu 140 atm gemessen worden (0 · n · 0,8), und zwar an Proben aus Pd-Draht (1 mm) und Pd-Folie (33 μm). Im Homogenitatsbereich waren die Isothermen fur Absorption und Desorption identisch,im Zweiphasengebiet wurde dagegen stets Hysterese beobachtet. Hier wurde jeweils die Desorptionskurve als Gleichgewichtsisotherme angesehen und zur Bestimmung von nαmax und nβmin durch Extrapolation herangezogen.
Messungen an Pd-Mohr im gleichen Druck- und Temperaturbereich zeigten eine Reihe von Besonderheiten, z. B. kleinere Suszeptibilitat und schmalere Hysterese im Vergleich zum kompakten Pd. Diese konnen auf die grose spezifische Oberflache des Pd-Mohrs zuruckgefuhrt werden sowie auf seine stark gestorte Gitterstruktur.
Die Lage des kritischen Punktes im Palladium-Wasserstoff-System konnte mit Hilfe der an kompaktem Pd durchgefuhrten Messungen mit verhaltnismasig groser Genauigkeit neu bestimmt werden: Tc = 291 ± 2°C; nc = 0,250 ± 0,005 mol H/mol Pd; pc = 19,7 ± 0,2 atm H2.
Die Messungen an Pd-Mohr lieferten innerhalb der Fehlerstreubreite dieselben Werte fur die kritische Temperatur und den kritischen Druck, wahrend fur das H/Pd-Verhaltnis unter Berucksichtigung erforderlicher Korrekturen ein etwas hoherer Wert, namlich nc = 0,260 ± 0,005 gefunden wurde.
241 citations
TL;DR: In this article, the authors bring together engineering properties for three classes of hydride-forming alloys (AB, AB5 and A2B) manufactured and marketed by Ergenics under the HY-STOR trade name.
Abstract: Rechargeable metal hydrides are being used for a wide variety of applications: mobile and stationary hydrogen storage, hydrogen purification, hydrogen recovery and separation, thermal compression, chemical heat pumps and refrigeration. Successful selection of metal hydrides for these and other proposed applications requires the knowledge of many engineering properties. In many cases these data are scattered widely in the literature or are simply not available.
In this paper we bring together engineering properties for three classes of hydride-forming alloys (AB, AB5 and A2B) manufactured and marketed by Ergenics under the HY-STOR trade name. The properties discussed are the plateau pressure-temperature relationship, hysteresis, the plateau slope, the hydrogen capacity and the heat capacity.
176 citations
130 citations