Magnetism and hydrogen absorption in UNiZn

Mašková, S.; Daniš, S.; Miliyanchuk, K.; Stelmakhovych, O.; Vondráčková, B.; Kolomiets, A.; Havela, L.

doi:10.1016/j.jallcom.2015.05.234

Cited by 4 publications

(3 citation statements)

References 25 publications

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“…Additionally, it yields a structural transition from the ZrNiAl to the AlB2-type structure. Interestingly, similar high volume expansion and structural change upon hydrogenation (+19.7%) was also evidenced in the isotypic intermetallic uranium compound UNiZn [20]. In this case, the crystal structure of the resulting hydride UNiZnH2.3 was not unambiguously solved between the AlB2-type structure and a derivative of this structure with an ordering of the Ni and Zn atoms.…”

Section: Structural Aspectsmentioning

confidence: 69%

Hydrogenation-induced cerium valence change in CeNiZn

Tencé

Heying

Janka

et al. 2017

Journal of Alloys and Compounds

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transition from a ZrNiAl-to an AlB2-type structure with a high volume cell expansion of +20.1 %. The magnetic, thermal and transport properties of CeNiZnH1.2(1) were investigated. Susceptibility and specific heat measurements do not reveal magnetic order down to 1.8 K but most likely the presence of ferromagnetic correlations due to the proximity of a ferromagnetic order or a nonmagnetic atom disorder spin-glass state. Moreover, the cerium valence is modified from an intermediate to a trivalent state, a change that results from the decrease of the hybridization strength between conduction and Ce(4f) electrons upon hydrogenation. Transport measurements also evidence a deviation from the typical resistivity behavior of metallic systems. Several scenarios are conceived to explain this change, in particular weak localization effect, knowing that it rarely occurs upon hydrogenation of intermetallics.

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Section: Structural Aspectsmentioning

confidence: 69%

Hydrogenation-induced cerium valence change in CeNiZn

Tencé

Heying

Janka

et al. 2017

Journal of Alloys and Compounds

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“…As a hydride with the stoichiometry UNiZnH 2.3 , i.e. analogous to UNiAlH 2.3 , it becomes antiferromagnetic (T N = 55 K) [125]. The structure corresponds to the AlB 2 type with the random Ni/Zn occupation of the B sites.…”

Section: Hydrides Of Ternary Compoundsmentioning

confidence: 99%

“…Individual compounds are placed rather arbitrarily on the Localization axis, reflecting presence and stability of U magnetic moments. Based on data from [116] and [125]. Reprinted from [27], Copyright (2022), with permission from Elsevier.…”

Section: Hydrides Of Ternary Compoundsmentioning

confidence: 99%

Hydrogen in actinides: electronic and lattice properties

Havela

Legut

Kolorenč³

2023

Rep. Prog. Phys.

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Hydrides of actinides, their magnetic, electronic, transport, and thermodynamic properties are discussed within a general framework of H impact on bonding, characterized by volume expansion, affecting mainly the 5f states, and a charge transfer towards H, which influences mostly the 6d and 7s states. These general mechanisms have diverse impact on individual actinides, depending on the degree of localization of their 5f states. Hydrogenation of uranium yields UH2 and UH3, binary hydrides that are strongly magnetic due to a 5f band narrowing and reduction of the 5f‐6d hybridization. Pu hydrides become magnetic as well, mainly as a result of the stabilization of the magnetic 5f 5 state and elimination of the admixture of the non‐magnetic 5f 6 component. Ab‐initio computational analyses, which for example suggest that the ferromagnetism of β‐UH3 is rather intricate involving two non‐collinear sublattices, are corroborated by spectroscopic studies of sputter‐deposited thin films, yielding a clean surface and offering a variability of compositions. It is found that valence‐band photoelectron spectra cannot be compared directly with the 5f n ground‐state density of states. Being affected by electron correlations in the excited final states, they rather reflect the atomic (n‐1) multiplets. Similar tendencies can be identified also in hydrides of binary and ternary intermetallic compounds. H absorption can be used as a tool for fine tuning of electronic structure around a quantum critical point. A new direction is represented by actinide polyhydrides with a potential for high‐temperature superconductivity.

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