Engineering Papers⌕ Search
Home/Archive/DOE OSTI

DOE OSTI · 3400832

Metal Atom (Dis)Order and Superconductivity in YCaH n ( n = 8–20) High-Pressure Superhydrides

Kimura, Masashi W. [State Univ. of New York (SUNY), Buffalo, NY (United States)] (ORCID:000900003595681X)·Jang, Seong Won [State Univ. of New York (SUNY), Buffalo, NY (United States)] (ORCID:0009000694456616)·Geng, Nisha [State Univ. of New York (SUNY), Buffalo, NY (United States)] (ORCID:0000000298495296)·Zurek, Eva [State Univ. of New York (SUNY), Buffalo, NY (United States)]
View original source ↗Read source document ↗Export metadata ↓

Abstract

High-pressure superhydrides have attracted much attention due to their high superconducting critical temperatures (T c s). Our density functional theory (DFT) calculations, focusing on YCaH n (n = 8–20) compositions, found a number of nearly isoenthalpic YCaH 8 phases, differing only in the arrangement of the metal atoms, suggesting the potential stability of metal alloy superhydrides. The computed T c s of the considered YCaH 8 phases were higher than those of the isostructural I 4/ mmm MH 4 parent compounds. DFT enthalpies suggested that YCaH 12 could also be disordered; however, the T c s of the ordered variants spanned a wide range from 105 to 253 K at 200 GPa, showing that alloying could either mildly enhance or drastically reduce T c from that of the $Im\bar{3}m$ MH 6 parents. Finally, for YCaH 18 and YCaH 20 , only a single dynamically stable ordered superhydride was found, which we attribute to the differences in the structures of the most stable MH 9 and MH 10 binary hydride parents.

Explore related subjects

anionschemical structuremetal atomssuperconductivitythermodynamic properties

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Kimura, Masashi W. [State Univ. of New York (SUNY), Buffalo, NY (United States)] (ORCID:000900003595681X), Jang, Seong Won [State Univ. of New York (SUNY), Buffalo, NY (United States)] (ORCID:0009000694456616), Geng, Nisha [State Univ. of New York (SUNY), Buffalo, NY (United States)] (ORCID:0000000298495296), Zurek, Eva [State Univ. of New York (SUNY), Buffalo, NY (United States)]. 2026-07-22. Metal Atom (Dis)Order and Superconductivity in YCaH n ( n = 8–20) High-Pressure Superhydrides. https://doi.org/10.1021/acs.inorgchem.6c02106

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related reports

DOE OSTI2026

A Ce 4+ Aluminum Hydride Complex

Complexes of reducing hydride ligands by high-oxidation state cerium are unknown due to the fundamental mismatch in their redox chemistry. Herein we report the synthesis, characterization, and reactivity of the first example of a Ce 4+ aluminum hydride complex. Synthetic strategies adapted from the preparation of Ce 4+ alkyl complexes facilitated the isolation of [Ce 4+ (κ 2 -H 3 AlC(TMS) 3 )(NP( t Bu) 3 ) 3 ] (CeHAl). The bonding and structure of this complex is characterized by single-crystal XRD, NMR, and UV–vis–NIR spectroscopy, and DFT computations. The fundamental reactivity profile is evaluated by cyclic voltammetry and small-molecule reactions.

anions↗
DOE OSTI2026

Hydride and Seek: Comparing Crystallographic Hydride Placement Techniques with an Open-Shell Cobalt Complex

Locating hydrides is crucial in organometallic chemistry but difficult to do accurately using X-ray diffraction. Electron diffraction has been proposed as a way to overcome this problem but has not been systematically compared to neutron diffraction and to quantum crystallography (Hirshfeld atom refinement, HAR) to test this hypothesis. Here, we present a comparative analysis of methods for a terminal cobalt hydride complex by comparing a single-crystal neutron diffraction reference structure to results from single-crystal X-ray diffraction with and without Hirshfeld atom refinement (HAR, NoSpherA2), density functional theory (DFT), and electron diffraction (3D-ED/MicroED) refined under kinematical and dynamical formalisms. Conventional X-ray diffraction gives lower precision than neutron diffraction as expected. Despite expected improvements, HAR gives systematic deviation from the neutron benchmark. Interestingly, optimized DFT equilibrium geometries are closer to the neutron value than the value from HAR. On the other hand, electron diffraction with a high-quality data set coupled with dynamical refinement localizes the hydride in difference maps and gives excellent agreement with the neutron data. Dynamical refinement is crucial, as kinematical refinement does not allow assignment of a hydride peak. This cross-modal comparison defines the conditions under which 3D-ED/MicroED delivers high-precision metal–hydride distances for this open-shell cobalt hydride.

anions↗
DOE OSTI2026

One Beam, Dual Insights: Simultaneous Chemical and Structural Changes in Nanopatterned Ceria under Reaction Conditions

Ceria’s interaction with hydrogen can proceed through multiple chemical forms (hydride, hydroxyl, and oxyhydroxide-like), with consequences for the oxidation state, density, and morphology that are rarely tracked in the same evolving state. Here, in this work, we show that under mild H 2 (and H 2 and CO 2 ) environments nanopatterned ceria undergoes oxidation-state changes accompanied by hydrogen incorporation that increases the effective electron density, establishing the following order: CeO 2 Hy > CeO 2 > CeO 2–x Hy > CeO 2–x . In parallel, the surface roughens in a chemically specific manner, with the largest changes coinciding with conditions where incorporated hydrogen is driven to react with oxygen supplied either by air exposure between experiments or by added CO 2 . We obtained these insights by using a single X-ray beam to simultaneously perform ambient-pressure X-ray photoelectron spectroscopy and grazing-incidence X-ray scattering on the same sample spot. Single-mode measurements can miss key ceria–H 2 transformations relevant to optimizing ceria-based hydrogenation catalysts and supports.

anions↗