Methods for neutron diffraction studies on hydride superconductors and other metal hydrides

2021 ◽  
Vol 130 (21) ◽  
pp. 215901
Author(s):  
Bianca Haberl ◽  
Mary-Ellen Donnelly ◽  
Jamie J. Molaison ◽  
Malcolm Guthrie ◽  
Reinhard Boehler
Keyword(s):  
Neutron Diffraction ◽  
Metal Hydrides

scholarly journals Study of hydrogen storage materials by neutron powder diffraction

2014 ◽  
Vol 70 (a1) ◽  
pp. C939-C939
Author(s):  
Jacques Huot ◽  
Catherine Gosselin ◽  
Thomas Bibienne ◽  
Roxana Flacau
Keyword(s):  
Neutron Diffraction ◽  
Hydrogen Storage ◽  
Room Temperature ◽  
Cast Alloy ◽  
Metal Hydrides ◽  
Structural Difference ◽  
Neutron Diffraction Study ◽  
Point Of View ◽  
Scattering Lengths ◽  
The One

Metal hydrides are interesting materials from a fundamental as well as practical point of view. Hydrogen storage applications have been the main driving force of research on these materials but lately uses such as thermal storage are considered. In this presentation we will review the use of neutron diffraction for the development of new metal hydrides. Two systems will be presented: BCC solid solution alloys and FeTi alloy. Ti-based BCC solid solutions are promising material for hydrogen storage applications which need high volumetric capacity and room temperature operation. One system that has been considered is Ti-V-Cr. Using only X-ray diffraction for structural identification does not provide information about hydrogen localization. Therefore, neutron diffraction is essential for complete determination of this class of hydrides. We will present examples of Ti-V-Cr compounds doped with Zr-Ni alloy. The peculiarity of this type of alloy is that, for neutron diffraction, the scattering lengths of the elements almost cancel. Therefore, the neutron pattern of as-cast alloy shows very small Bragg peaks but the advantage is that the hydride for is very easy to see and analyze. Another good candidate for hydrogen storage applications is the intermetallic compound TiFe which operates at around room temperature (RT) under mild pressure conditions. However one disadvantage of TiFe alloy synthesized by conventional metallurgical method is its poor activation characteristics. The alloy reacts with hydrogen only after complicated activation procedure involving exposure to high temperature (~4000C) and high pressure for several days. Recently we found that by doping this alloy with Zr and Zr7Ni10 the activation could be easily done at room temperature. We present here a neutron diffraction study of these compounds that shows the structural difference between the activated compound and the one cycled under hydrogen.

scholarly journals Study of Ti-V-Cr metal hydrides by neutron powder diffraction

2014 ◽  
Vol 70 (a1) ◽  
pp. C1762-C1762
Author(s):  
Thomas Bibienne ◽  
Roxana Flacau ◽  
Jean-Louis Bobet ◽  
Jacques Huot
Keyword(s):  
Neutron Diffraction ◽  
Raw Materials ◽  
Cast Alloy ◽  
Metal Hydrides ◽  
Point Of View ◽  
X Ray ◽  
Practical Applications ◽  
Slow Kinetics ◽  
Melt Synthesis

Metal hydrides are interesting materials from a fundamental as well as practical point of view. In particular, Ti-based BCC solid solutions are considered as promising candidates for mobile applications because of their high volumetric capacities and room temperature operation. However, the slow kinetics of the first hydrogenation, the so-called activation step, is an important hurdle in the use of these alloys for practical applications. It has recently been shown that doping a Ti-V-Cr composition with Zr7Ni10 leads to a fast activation kinetic without heating treatment [1]. We studied the effect of this doping on two new Ti-V-Cr compositions: 52Ti-12V-36Cr and 42Ti-21V-37Cr. Two different doping methods were investigated: i) a single-melt synthesis where the raw materials (i.e. Ti, V, Cr, Zr and Ni) chunks were mixed and arc-melted; ii) co-melt synthesis where 52Ti-12V-36Cr and 7Zr-10Ni were arc-melted independently and thereafter re-melted together. Using only X-ray diffraction for structural identification does not provide information about hydrogen localization. Therefore, neutron diffraction is essential for complete determination of this class of hydrides. The peculiarity of the present alloys is that, for neutron diffraction, the scattering lengths of the elements almost cancel. Therefore, the neutron pattern of as-cast alloy shows very small Bragg peaks but the advantage is that the hydride is very easy to see and analyze. We performed in-situ neutron diffraction experiments during dehydrogenation of these materials to see the transition from the dihydride to monohydride. These measurements were complementary to X-ray and synchrotron radiation diffraction and enabled a better crystal structure determination of these alloys

scholarly journals Study of hydrogen storage of the TiFe alloy by neutron powderdiffraction

2014 ◽  
Vol 70 (a1) ◽  
pp. C1767-C1767
Author(s):  
Catherine Gosselin ◽  
Jacques Huot ◽  
Roxana Flacau
Keyword(s):  
Neutron Diffraction ◽  
Hydrogen Storage ◽  
Room Temperature ◽  
Low Cost ◽  
Sorption Property ◽  
Metal Hydrides ◽  
Structural Difference ◽  
Neutron Diffraction Study ◽  
Point Of View ◽  
Practical Applications

Metal hydrides are interesting materials from a fundamental as well as practical point of view. Hydrogen storage applications have been the main driving force of research on these materials but lately, uses such as thermal storage are considered. In this presentation, we will review the use of neutron diffraction for the development of new metal hydrides. A good candidate for hydrogen storage applications is the low cost intermetallic compound TiFe which operates near room temperature (RT) under mild pressure conditions. However, the biggest disadvantage of TiFe alloy synthesized by conventional metallurgical method is it poor activation characteristics [1]. The alloy reacts with hydrogen only after complicated activation procedure involving exposure to high temperature (~4000C) and high pressure for several days. In the '90, some researches showed that the change in the nanocristallinity can modify the sorption property of the TiFe[2]. Other research works found that palladium increase the contaminant resistance. However, addition of palladium is too expansive for practical applications [3]. Recently, we found that, when doping TiFe with Zr and Zr7Ni10, the activation could be easily done at room temperature. We present here a neutron diffraction study of these compounds that shows the structural difference between the activated compound and the one cycled under hydrogen.

Neutron Diffraction Studies of Metal Hydrides

1981 ◽  
pp. 81-103 ◽  
Author(s):  
Hajime Asano ◽  
Makoto Hirabayashi
Keyword(s):  
Neutron Diffraction ◽  
Metal Hydrides

Electron microscopy of niobium and tantalum hydrides

1978 ◽  
Vol 36 (1) ◽  
pp. 644-645
Author(s):  
T. Schober
Keyword(s):  
Electron Microscopy ◽  
Heat Storage ◽  
Measurement Techniques ◽  
Metal Hydrides ◽  
Detailed Understanding ◽  
Storage Devices ◽  
Unit Cells ◽  
Endothermic Reactions ◽  
Hydrogen Reactions ◽  
New Phase

Nb, Ta and V are prototype substances for the study of the endothermic reactions of H with metals. Such metal-hydrogen reactions have gained increased importance due to the application of metal-hydrides in hydrogen- und heat storage devices. Electron microscopy and diffraction were demonstrated to be excellent methods in the study of hydride morphologies and structures (1). - Figures 1 and 2 show the NbH and TaH phase diagrams (2,3,4). EM techniques have contributed substantially to the elucidation of the structures and domain configurations of phases β, ζ and ε (1,4). Precision length measurement techniques of distances in reciprocal space (5) recently led to a detailed understanding of the distortions of the unit cells of phases ζ and ε (4). In the same work (4) the existence of the new phase η was shown. It is stable near -68 °C. The sequence of transitions is thus below 70 %.

Texture measurements in Al2O3 using BEKP

1994 ◽  
Vol 52 ◽  
pp. 608-609
Author(s):  
M. D. Vaudin ◽  
J. P. Cline
Keyword(s):  
Neutron Diffraction ◽  
Rapid Method ◽  
Crystallographic Orientation ◽  
Specimen Surface ◽  
X Ray Diffraction ◽  
Anisotropic Crystal ◽  
X Ray ◽  
Verification Method ◽  
Crystal Properties ◽  
Backscattered Electron

The study of preferred crystallographic orientation (texture) in ceramics is assuming greater importance as their anisotropic crystal properties are being used to advantage in an increasing number of applications. The quantification of texture by a reliable and rapid method is required. Analysis of backscattered electron Kikuchi patterns (BEKPs) can be used to provide the crystallographic orientation of as many grains as time and resources allow. The technique is relatively slow, particularly for noncubic materials, but the data are more accurate than any comparable technique when a sufficient number of grains are analyzed. Thus, BEKP is well-suited as a verification method for data obtained in faster ways, such as x-ray or neutron diffraction. We have compared texture data obtained using BEKP, x-ray diffraction and neutron diffraction. Alumina specimens displaying differing levels of axisymmetric (0001) texture normal to the specimen surface were investigated.BEKP patterns were obtained from about a hundred grains selected at random in each specimen.

A study of oxygen and vacancy ordering in YBa2Cu3O7−x

1989 ◽  
Vol 47 ◽  
pp. 164-165
Author(s):  
Y. P. Lin ◽  
A. H. O’Reilly ◽  
J. E. Greedan ◽  
M. Post
Keyword(s):  
Electron Microscopy ◽  
Neutron Diffraction ◽  
Oxygen Content ◽  
Carbon Film ◽  
Nitrogen Atmosphere ◽  
Vacancy Ordering ◽  
Powder Samples ◽  
Vacancy Chains ◽  
Chain Ordering

In the basal planes of the orthorhombic YBa2Cu3O7-X compound with x=0.07, which has a Tc of around 90K, chains of copper-oxygen are formed along the [010] direction. Previous investigations on the variation of Tc with oxygen content have shown the existence of a plateau at Tc = 60K for x=0.3 to 0.4, suggesting the presence of a separate phase. This phase has also been identified to be orthorhombic, but with a 2x superlattice along [100] of the parent structure, and the superlattice has been attributed to the formation of alternating copper-oxygen and copper-vacancy chains. In our work, we have studied the chain ordering phenomenon by electron microscopy and neutron diffraction on samples with different oxygen contents. We report here some of our electron microscopy findings for samples with x=0.4.Powder samples of YBa2Cu3O7-X were prepared by controlled re-oxidation of previously reduced material. For electron microscopy, the sample was dry ground using a mortar and pestle in a dry nitrogen atmosphere without the use of any solvent and transferred dry onto holey carbon film for examination in a Philips CM12 microscope.

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