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Crystal structure evolution of complex metal aluminum hydrides upon hydrogen release

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Journal of Energy Chemistry 2020年第3期29卷 133-143页

作者： Claudia Weidenthaler Max-Planck-Institut für Kohlenforschung 45470 Mülheim an der RuhrGermany

Complex aluminum hydrides have been widely studied as potential hydrogen storage materials but also,for some time now, for electrochemical applications. This review summarizes the crystal structures of alkali and alkaline earth aluminum hydrides and correlates structure properties with physical and chemical properties of the hydride compounds. The crystal structures of the alkali metal aluminum hydrides change significantly during the stepwise dehydrogenation. The general pathway follows a transformation of structures built of isolated [AlH4]- tetrahedra to structures built of isolated [Al H6]3- *** crystal structure relations in the group of alkaline earth metal aluminum hydrides are much more complicated than those of the alkali metal aluminum hydrides. The structures of the alkaline earth metal aluminum hydrides consist of isolated tetrahedra but the intermediate structures exhibit chains of cornershared octahedra. The coordination numbers within the alkali metal group increase with cation sizes which goes along with an increase of the decomposition temperatures of the primary hydrides. Alkaline earth metal hydrides have higher coordination numbers but decompose at slightly lower temperatures than their alkali metal counterparts. The decomposition pathways of alkaline metal aluminum hydrides have not been studied in all cases and require future research.

关键词： Complex aluminum hydrides Hydrogen storage Crystal structure

Age stability of La(Fe,Si)_(13) hydrides with giant magnetocaloric effects

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Rare Metals 2022年第3期41卷 992-1001页

作者： He Zhou Yi Long Salvatore Miraglia Florence Porcher Hu Zhang School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Tianjin College University of Science and Technology BeijingTianjin 301830China CNRS Institut NeelUniversite Grenoble Alpes25 Rue des Martyrs38042 GrenobleFrance Laboratoire Leon Brillouin UMR12 CEA-CNRSBat.563 CEA Saclay91191 Gif sur Yvette CedexFrance

The Curie temperatures(T_(C))of La_(0.7)Ce_(0.3)Fe_(13-x-y)Mn_(x)Si_(y)compounds that are hydrogenated to saturation are raised to near room *** age stability was inves-tigated for the fully hydrogenated La_(0.7)Ce_(0.3)Fe_(11.5-x)Mn_(x)Si_(1.5) *** result indicates that the H content will slowly decrease in the hydrides,leading to a decrease in T_(C).However,no age splitting is observed after the hydrides are held at room temperature for two years,indicating the excellent age stability of the *** structural analysis by neutron diffrac-tion shows that Mn atoms preferentially substitute Fe in the 96i *** T_(C)of La_(0.7)Ce_(0.3)Fe_(11.55-y)Mn_(y)Si_(1.45)hydrides can be adjusted to the desired working temperature by regulating Mn content based on the linear relationship between T_(C)and Mn ***,the La_(0.7)Ce_(0.3)Fe_(11.55-y)Mn_(y)Si_(1.45)hydrides exhibit a giant magnetic entropy change of 15 J·kg^(-1)·K^(-1) under a low magneticfield change of 0-1 *** a result,the giant magnetocaloric effect,linearly adjustable T_(C),and excel-lent age stability make the La_(0.7)Ce_(0.3)Fe_(11.55-y)Mn_(y)Si_(1.45)hydrides be one of the ideal candidates for room temperature magnetic refrigerants.

关键词： Magnetocaloric effect La(Fe,Si)_(13) hydrides Stability

Stoichiometric evolutions of PH3 under high pressure:implication for high-Tc superconducting hydrides

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National Science Review 2019年第3期6卷 524-531页

作者： Ye Yuan Yinwei Li Guoyong Fang Guangtao Liu Cuiying Pei Xin Li Haiyan Zheng Ke Yang Lin Wang Center for High Pressure Science and Technology Advanced Research School of Physics and Electronic Engineering Jiangsu Normal University Key Laboratory of Carbon Materials of Zhejiang Province College of Chemistry and Materials Engineering Wenzhou University Department of Physics Fudan University Shanghai Institute of Applied Physics Chinese Academy of Sciences

The superconductivity of hydrides under high pressure has attracted a great deal of attention since the recent observation of the superconducting transition at 203 K in strongly compressed *** has been realized that the stoichiometry of hydrides might change under high pressure,which is crucial in understanding the superconducting *** this study,PH3was studied to understand its superconducting transition and stoichiometry under high pressure using Raman,IR and X-ray diffraction measurements,as well as theoretical ***3is stable below 11.7 GPa and then it starts to dehydrogenate through two dimerization processes at room temperature and pressures up to 25 *** resulting phosphorus hydrides,P2H4and P4H6,were verified experimentally and can be recovered to ambient *** further compression above 35 GPa,the P4H6directly decomposed into elemental *** temperature can greatly hinder polymerization/decomposition under high pressure and retains P4H6up to at least 205 *** superconductivity transition temperature of P4H6is predicted to be 67 K at 200 GPa,which agrees with the reported result,suggesting that it might be responsible for superconductivity at higher *** results clearly show that P2H4and P4H6are the only stable P–H compounds between PH3and elemental phosphorus,which is helpful for shedding light on the superconducting mechanism.

关键词： high pressure hydrides superconductivity stoichiometric evolution

High T_(c) superconductivity in layered hydrides XH_(15) (X = Ca, Sr, Y, La) under high pressures

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Frontiers of physics 2022年第6期17卷 107-113页

作者： Yue Chen Zhengtao Liu Ziyue Lin Qiwen Jiang Mingyang Du Zihan Zhang Hao Song Hui Xie Tian Cui Defang Duan State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchun 130012China Institute of High Pressure Physics School of Physical Science and TechnologyNingbo UniversityNingbo 315211China

The theoretical predictions and experimental synthesis of H_(3)S and LaH_(10) superconductors with record high superconducting transition temperatures(T_(c))have promoted the hydrogen-based superconducors to be a research hotspot in the field of solid-state ***,we predict an unprecedented layered structure CaH15,with high T_(c) of 189 K at 200 GPa using ab initio *** concerns the novel structure,one layer is made of a hydrogen nonagon,the other layer consists of a Ca atom and six H_(2) molecular units surrounding the Ca *** layered structure was also found in SrH_(15),YH_(15),and LaH_(15) at high pressures,each materials exhibit high T_(c) especially YH_(15) can reach above 200 K at 220 *** represents the second class of layered superhydrides with high value of Tc after pentagraphene like HfH10.

关键词： high pressure hydrides superconductivity ab initio calculation

Theory-directed discovery of high-temperature superconductivity in clathrate hydrides at high pressure

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The Innovation 2022年第2期3卷 9-10页

作者： Xin Zhong John S.Tse Russell J.Hemley Hanyu Liu International Center for Computational Method&Software and State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchun 130012China Department of Physics and Engineering Physics University of SaskatchewanSaskatoon S7N 5E2Canada Departments of Physics Chemistryand Earth and Environmental SciencesUniversity of Illinois ChicagoChicagoIL 60607USA International Center of Future Science Jilin UniversityChangchun 130012China

The search for room-temperature superconductivity has been one of the great challenges in condensedmatter physics ever since the first observation of superconductivity with a critical temperature(T_(c))of 4 K in mercury in *** recent years,we have been witness to the successful observation of superconductivity in highly compressed SH_(3)(T_(c)=203 K at 155 GPa)and classes of clathrate hydrides(e.g.,CaH_(6),YH_(6),YH_(9),LaH_(10)).

关键词： hydrides superconductivity high

IN-SITU ELECTRON MICROSCOPY STUDY ON PRECIPITATION OF ZIRCONIUM hydrides INDUCED BY STRESS AND STRAIN IN ZIRCALOY-2

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Acta Metallurgica Sinica(English Letters) 1989年第6期2卷 412-417页

作者： ZHOU Bangxin ZHENG Sikui WANG Shunxin Southwest Centre for Nuclear Reactor Engineering Research and Design,Chengdu,China [Originally published in ACTA METALL SIN(CHINESE EDN)25(3)1989 pp A190—A195, Southwest Centre for Nuclear Reactor Engineering Research and Design,Chengdu,China

The precipitation process of zirconium hydrides induced by stress and strain was investigated by means of electron microscopy *** precipitating hydrides induced by stress were found to be γ phase with orientation relationship of (110)_γ‖(110)_(αZr),(001)_γ‖ (0001)_(αZr) between γ-hydrides and surrounding *** growth rate of γ-hydrides which was much faster along [110] direction brought them in taper *** fracture of y-hydrides,a new one will precipitate at the tip of *** is the essential process of hydrogen-induced delayed cracking in *** precipitating hydrides induced by strain were found to be δ phase with both orientation relationships of(111)_δ‖(0001)_(αZr),(110)_δ‖ (110)_(αZr) or (010)_δ‖(0001)_(αZr),(001)_δ‖(110)_(αZr)between δ-hydride and surrounding *** δ-hydrides become much finer as the strain rate increased.

关键词： Zircaloy-2 precipitation of hydrides hydrides hydrogen-induced delayed cracking

Clear evidence against superconductivity in hydrides under high pressure

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Matter and Radiation at Extremes 2022年第5期7卷 55-64页

作者： J.E.Hirsch F.Marsiglio Department of Physics University of CaliforniaSan DiegoLa JollaCalifornia 92093-0319USA Department of Physics University of AlbertaEdmontonAlberta T6G 2E1Canada

The Meissner effect,magnetic field expulsion,is a hallmark of *** with it,superconductors exclude applied magnetic ***,Minkov et al.[***.13,3194(2022)]presented experimental results reportedly showing“definitive evidence of the Meissner effect”in sulfur hydride and lanthanum hydride under high pressure,and Eremets et al.[***.35,965(2022)]argued that“the arguments against superconductivity(in hydrides)can be either refuted or explained.”Instead,we show here that the evidence presented in those papers does not support the case for superconductivity in these *** with experimental evidence discussed in earlier papers,we argue that this strongly suggests that hydrides under pressure are not high-temperature superconductors.

关键词： hydrides materials. superconductivity

Superconductivity in La and Y hydrides: Remaining questions to experiment and theory

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Matter and Radiation at Extremes 2020年第2期5卷 62-72页

作者： Viktor Struzhkin Bing Li Cheng Ji Xiao-Jia Chen Vitali Prakapenka Eran Greenberg Ivan Troyan Alexander Gavriliuk Ho-kwang Mao Center for High Pressure Science and Technology Advanced Research ShanghaiChina Geophysical Laboratory Carnegie Institution of WashingtonWashingtonDC 20015USA Center for Advanced Radiation Sources The University of Chicago5640 South Ellis AvenueChicagoIllinois 60637USA Federal Scientific Research Center Crystallography and Photonics Russian Academy of Sciences59 Leninskii Pr-tMoscow 119333Russia Institute for Nuclear Research Russian Academy of SciencesMoscowTroitsk 108840Russia

Recent reports of the superconductivity in hydrides of two different families(covalent lattice,as in SH3 and clathrate-type H-cages containing La and Y atoms,as in LaH10 and YH6)have revealed new families of high-Tc materials with Tc’s near room temperature *** findings confirm earlier expectations that hydrides may have very high Tc’s due to the fact that light H atoms have very high vibrational frequencies,leading to high Tc values within the conventional Bardeen–Cooper–Schrieffer phonon mechanism of ***,as is pointed out by Ashcroft,it is important to have the metallic hydrogen“alloyed”with the elements added to *** concept of a metallic alloy containing a high concentration of metal-like hydrogen atoms has been instrumental in finding new high-Tc *** new superhydride“roomtemperature”superconductors are stabilized only at very high pressures above 100 GPa,making the experimental search for their superconducting properties very *** will review the current experimental and theoretical results for LaH10−x and YH6−x superhydrides.

关键词： hydrides alloy metallic

Are hydrides under high-pressure-high-temperature superconductors?

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National Science Review 2024年第7期11卷 9-12页

作者： J.E.Hirsch Department of Physics University of California

Contrary to the current consensus, I argue that the existing evidence for high-temperature superconductivity in hydrides under high pressure is not compelling. I suggest that the focus of the field should urgently shift to establish unequivocally experimentally whether or not superconductivity in pressurized hydrides exists, instead of continuing to search for new materials that might show elusive signals of unproven superconductivity at ever higher temperatures. The implications of a negative finding for the theoretical understanding of superconductivity are discussed.

关键词： hydrides