Flourishing rare earth superhydrides are a class of recently discovered materials that exhibit near-room-temperature superconductivity at high pressures,ushering in a new era of superconductivity research at high pres...Flourishing rare earth superhydrides are a class of recently discovered materials that exhibit near-room-temperature superconductivity at high pressures,ushering in a new era of superconductivity research at high pressures.Yttrium superhydrides drew the most attention among these superhydrides due to their abundance of stoichiometries and excellent superconductivities.Here,we carried out a comprehensive study of yttrium superhydrides in a wide pressure range of 140 GPa-300 GPa.We successfully synthesized a series of superhydrides with the compositions of YH_(4),YH_(6),YH_(7),and YH_(9),and reported superconducting transition temperatures of 82 K at 167 GPa,218 K at 165 GPa,29 K at 162 GPa,and230 K at 300 GPa,respectively,as evidenced by sharp drops in resistance.The structure and superconductivity of YH_(4) were taken as a representative example and were also examined using x-ray diffraction measurements and the superconductivity suppression under external magnetic fields,respectively.Clathrate YH_(10),a candidate for room-temperature superconductor,was not synthesized within the study pressure and temperature ranges of up to 300 GPa and 2000 K.The current study established a detailed foundation for future research into room-temperature superconductors in polynary yttrium-based superhydrides.展开更多
Extended hydrogen-rich frameworks stabilized under high pressure are essential for achieving high-temperature superconductivity in metal hydrides,where metal atoms contribute both charge and intrinsic precompression.I...Extended hydrogen-rich frameworks stabilized under high pressure are essential for achieving high-temperature superconductivity in metal hydrides,where metal atoms contribute both charge and intrinsic precompression.In contrast,p-block nonmetal hydrides lack such extended hydrogenic connectivity.Here,using first-principles crystal structure search calculations,we identify three nitrogen-based superhydrides-NH_(10),NH_(11),and NH_(12)-each featuring a unique extended H sublattice:corrugated graphene-like hydrogen layers in NH_(10),planar H_(16)-ring sheets in NH11,and a fully three-dimensional,densely connected H framework in NH12.These structures are stabilized by NH_(4)^(+)units,which donate charge in a manner analogous to metal atoms in conventional metal superhydrides.Remarkably,NH_(10)exhibits a superconducting critical temperature(T_(c))of 190 K at 200 GPa,driven by strong electron-phonon coupling between H-1s states and low-frequency hydrogen-derived phonon modes-a mechanism notably distinct from that of hydrogen cages in LaH_(10)and CaH_(6).The predicted T_(c)values of NH_(11)and NH_(12)also exceeds 130 K.Our work introduces a new paradigm for designing nonmetal superhydrides with structurally engineered hydrogenic frameworks.展开更多
Metal superhydride compounds(MSHCs)have attracted much attention in the fields of high-pressure physics due to the superconductivity properties deriving from the metallic-hydrogen-like characteristics and relatively m...Metal superhydride compounds(MSHCs)have attracted much attention in the fields of high-pressure physics due to the superconductivity properties deriving from the metallic-hydrogen-like characteristics and relatively mild synthesis conditions.However,their energetic performance and related potential applications are still open issues till now.In this study,CaH_(6)and NbH_(3),which exhibit evidently differences in their geometric and electronic structures,were chosen as examples of MSHCs to investigate their energetic performance.The structure,bonding features and energetic performance of CaH_(6)and NbH_(3)were predicted based on first-principles calculations.Our results reveal that high-pressure MSHCs always exhibit high energy densities.The range of theoretical energy density of CaH_(6)was predicted as 2.3-5.3 times of TNT,while the value for NbH_(3)was predicted as 1.2 times of TNT.Our study further uncover that CaH_(6)has outstanding energetic properties,which are ascribed to the three-dimensional(3D)aromatic H sublattice and the strong covalent bonding between the H atoms.Moreover,the detonation process and products of rapid energy-release stage of CaH_(6)were simulated via AIMD method,based on which its superior combustion performance was predicted and its specific impulse was calculated as 490.66 s.This study not only enhances the chemical understanding of MSHCs,but also extends the paradigm of traditional energetic materials and provides a new route to design novel high energy density materials.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1400203 and 2018YFA0305900)the National Natural Science Foundation of China(Grant Nos.52090024,11874175,12074139,12074138,11874176,and 12034009)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33000000)Program for JLU Science and Technology Innovative Research Team(JLUSTIRT)。
文摘Flourishing rare earth superhydrides are a class of recently discovered materials that exhibit near-room-temperature superconductivity at high pressures,ushering in a new era of superconductivity research at high pressures.Yttrium superhydrides drew the most attention among these superhydrides due to their abundance of stoichiometries and excellent superconductivities.Here,we carried out a comprehensive study of yttrium superhydrides in a wide pressure range of 140 GPa-300 GPa.We successfully synthesized a series of superhydrides with the compositions of YH_(4),YH_(6),YH_(7),and YH_(9),and reported superconducting transition temperatures of 82 K at 167 GPa,218 K at 165 GPa,29 K at 162 GPa,and230 K at 300 GPa,respectively,as evidenced by sharp drops in resistance.The structure and superconductivity of YH_(4) were taken as a representative example and were also examined using x-ray diffraction measurements and the superconductivity suppression under external magnetic fields,respectively.Clathrate YH_(10),a candidate for room-temperature superconductor,was not synthesized within the study pressure and temperature ranges of up to 300 GPa and 2000 K.The current study established a detailed foundation for future research into room-temperature superconductors in polynary yttrium-based superhydrides.
基金supported by the Natural Science Foundation of China(grant nos.22372142,12304028,and 12404027)Foreign Ex-pert Introduction Program,China(G2023003004L)+6 种基金Central Guiding Local Science and Technology Development Fund Projects,China(236Z7605G)Natural Science Foundation of Hebei Province,China(grant nos.B2024203051,A2024203023,and A2024203002)Science and Technology Project of Hebei Education Department,China(grant no.JZX2023020)Innovation Capability Improvement Project of Hebei province,China(22567605H)Hebei Province Yan Zhao Huang Jin Tai Talent Program,China(Postdoctoral Platform,B2024003003)A.B.acknowledges financial support from the Spanish Ministry of Science and Innovation,Spain(Grant No.PID2022-139230NB-I00)the Department of Education,Universities and Research of the Basque Government,Spain and the University of the Basque Country,Spain(Grant No.IT1707-22).
文摘Extended hydrogen-rich frameworks stabilized under high pressure are essential for achieving high-temperature superconductivity in metal hydrides,where metal atoms contribute both charge and intrinsic precompression.In contrast,p-block nonmetal hydrides lack such extended hydrogenic connectivity.Here,using first-principles crystal structure search calculations,we identify three nitrogen-based superhydrides-NH_(10),NH_(11),and NH_(12)-each featuring a unique extended H sublattice:corrugated graphene-like hydrogen layers in NH_(10),planar H_(16)-ring sheets in NH11,and a fully three-dimensional,densely connected H framework in NH12.These structures are stabilized by NH_(4)^(+)units,which donate charge in a manner analogous to metal atoms in conventional metal superhydrides.Remarkably,NH_(10)exhibits a superconducting critical temperature(T_(c))of 190 K at 200 GPa,driven by strong electron-phonon coupling between H-1s states and low-frequency hydrogen-derived phonon modes-a mechanism notably distinct from that of hydrogen cages in LaH_(10)and CaH_(6).The predicted T_(c)values of NH_(11)and NH_(12)also exceeds 130 K.Our work introduces a new paradigm for designing nonmetal superhydrides with structurally engineered hydrogenic frameworks.
文摘Metal superhydride compounds(MSHCs)have attracted much attention in the fields of high-pressure physics due to the superconductivity properties deriving from the metallic-hydrogen-like characteristics and relatively mild synthesis conditions.However,their energetic performance and related potential applications are still open issues till now.In this study,CaH_(6)and NbH_(3),which exhibit evidently differences in their geometric and electronic structures,were chosen as examples of MSHCs to investigate their energetic performance.The structure,bonding features and energetic performance of CaH_(6)and NbH_(3)were predicted based on first-principles calculations.Our results reveal that high-pressure MSHCs always exhibit high energy densities.The range of theoretical energy density of CaH_(6)was predicted as 2.3-5.3 times of TNT,while the value for NbH_(3)was predicted as 1.2 times of TNT.Our study further uncover that CaH_(6)has outstanding energetic properties,which are ascribed to the three-dimensional(3D)aromatic H sublattice and the strong covalent bonding between the H atoms.Moreover,the detonation process and products of rapid energy-release stage of CaH_(6)were simulated via AIMD method,based on which its superior combustion performance was predicted and its specific impulse was calculated as 490.66 s.This study not only enhances the chemical understanding of MSHCs,but also extends the paradigm of traditional energetic materials and provides a new route to design novel high energy density materials.
