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Microstructural landscape of amorphous carbon

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National science Review 2024年第5期11卷 94-95页

作者： Huiyang Gou center for high pressure science and technology advanced Research (HPSTAR)

Due to its diverse bonding hybridization forms (sp, sp2and sp3), amorphous carbon exhibits multifaceted properties and important application prospects, which have aroused extensive research interest[1–5]. In amorphous solids, some degree of atomic short-to medium-range order is thought to be ubiquitous, and the recent synthesis of new amorphous carbon has further increased our understanding of the atomic disorder in materials [4].

关键词： landscape amorphous carbon microstructural

pressure-induced hydrogen-dominant high-temperature superconductors

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National science Review 2024年第7期11卷 14-16页

作者： Ho-kwang Mao Shanghai advanced Research in Physical sciences center for high pressure science and technology advanced Research

Recent studies of hydrogen-dominant（superhydride） materials have led to putative discoveries of near-room temperature superconductivity at high pressures. The idea started more than half-a-century ago as a by-product of the quest for metallic hydrogen for which a natural consequence of its very high Debye temperature and phonon frequency due to the very low mass of the hydrogen atoms would lead to a high superconducting critical temperature （Tc） in weak coupling Bardeen-Cooper-Schrieffer（BCS） expression.

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Asthenosphere dynamics based on the H2O dependence of element diffusivity in olivine

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National science Review 2021年第4期8卷 9-11页

作者： Tomoo Katsura Hongzhan Fei Bayerisches Geoinstitut University of Bayreuth center for high pressure science and technology advanced Research

The oceanic asthenosphere is one of the most enigmatic regions in the Earth’s interior. The presence of seismic lowvelocity zones implies high softness at the top of the asthenosphere, which may cause smooth plate mo... 详细信息

关键词： scanning tunneling microscopy phenyl-based molecular film electronic correlation electron-vibration coupling Kondo effect

Electronic and optical properties of lithium niobate under high pressure: A first-principles study

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Chinese Physics B 2015年第7期24卷 420-425页

作者：桑丹丹王庆林韩崇陈凯潘跃武 Mathematics and Physical sciences technology Xuzhou Institute of Technology center for high pressure science and technology advanced Research

We theoretically study the structural, electronic, and optical properties of lithium niobate under pressure using the plane-wave pseudopotential density functional theory by CASTEP code. It was found that there is a phase transition from the R3 c structure to the Pnma structure at a pressure of 18.7 GPa. The Pnma structure was dynamically stable according to the calculation of phonon dispersion. From the charge density distributions, there exist covalent interactions along the Nb–O bond. The hybridization between O 2p and Nb 4d orbital in the Pnma phase increases with increasing pressure, while it is not changed in the R3c phase. With increasing pressure, the average Nb–O bond length decreases and the Nb–O bond population increases, indicating the increased covalent character between Nb and O atoms under high pressure at Pnma phase, which leads to the increased hybridization between O 2p and Nb 4d orbitals. Furthermore, the optical dielectric function, refractive index, extinction coefficient, electron energy, loss and reflectivity are calculated.

关键词： pressure electronic structure optical properties hybridization

Yi-Gang Xu: the Earth's deep interior holds the key to habitability

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National science Review 2021年第4期8卷 35-38页

作者： Jin Liu Ho-Kwang Mao the center for high pressure science and technology advanced Research (HPSTAR) HPSTAR

The deep Earth is the engine of whole Earth systems and plays a key role in surface evolution and geological hazards. Scientists have been deciphering the internal processes that shape our habitable planet, especially since the formulation of plate tectonics theory. To date, how the deep Earth works remains mysterious. At the end of 2020,

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Phase Stability and Hydroxyl Vibration of Brucite Mg(OH)_(2) at high pressure and high Temperature

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Chinese Physics Letters 2021年第3期38卷 111-115页

作者： Wei-Bin Gui Chao-Shuai Zhao Jin Liu center for high pressure science and technology advanced Research(HPSTAR) Beijing 100094China

Brucite Mg(OH)_(2) is an archetypal hydrous mineral and it has attracted a great deal of ***,little is known about the evolution of hydroxyl groups in brucite with respect to subduction *** carried out Raman measurements up to 15.4 GPa and 874 K via an externally heated diamond anvil cell,investigating the stability of brucite under the conditions relevant to subducting *** hydroxyl vibration mode A_(1g)(I) of brucite is weakened under simultaneous high pressure-temperature ***,the presence of carbonated solution can destabilize the hydroxyl groups of brucite at low *** results suggest that brucite releases water when reacting with hydrogen carbonate ion to form magnesite MgCO_(3) in subduction *** implies that the global water cycle is largely coupled with the deep carbon cycle in Earth’s interior.

关键词： hydroxyl cycle implies

Chemical transformations of n-hexane and cyclohexane under the upper mantle conditions

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Geoscience Frontiers 2021年第2期12卷 1010-1017页

作者： Xin Yang Yapei Li Yajie Wang Haiyan Zheng Kuo Li Ho-kwang Mao center for high pressure science and technology advanced Research Beijing100094China

Alkanes are an important part of petroleum,the stability of alkanes under extreme conditions is of great significance to explore the origin of petroleum and the carbon cycle in the deep ***,we performed Raman and infrared(IR)spectroscopy studies of n-hexane and cyclohexane under high pressure up to~42 GPa at room temperature(RT)and high temperature(HT).n-Hexane and cyclohexane undergo several phase transitions at RT around 1.8,8.5,18 GPa and 1.1,2.1,4.6,13,30 GPa,respectively,without any chemical *** using resistive heating combined with diamond anvil cell at pressure up to 20 GPa and temperature up to 1000 K,both n-hexane and cyclohexane decompose to hydrogenated graphitic carbon and n-hexane exhibits higher stability than *** results indicate that hydrocarbons tend to dehydrogenate in the upper mantle,and the extension of carbon chains may lead to the formation of some unsaturated compounds and eventually transfer into graphitic products.

关键词： Alkanes high pressure and high temperature Dehydrogenation Hydrocarbon Upper mantle conditions

Deep mantle hydrogen in the pyrite-type FeO_(2)–FeO_(2)H system

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Geoscience Frontiers 2021年第2期12卷 975-981页

作者： Qingyang Hu Jin Liu center for high pressure science and technology advanced Research(HPSTAR) Beijing100094China

The pyrite-type FeO_(2)and FeO_(2)H were synthesized at the pressure-temperature conditions relevant to Earth’s deep lower *** the water-iron reaction,the pyrite-phase is a good candidate to explain the chemical heterogeneities and seismological anomalies at the bottom of the *** solid solution of pyrite-type FeO_(2)and FeO_(2)H,namely the FeO_(2)Hx(0≤x≤1),is particularly interesting and introduces puzzling chemical states for both the O and H atoms in the deep *** the role of H in the FeO_(2)–FeO_(2)H system has been primarily investigated,discrepancies *** this work,we summarize recent progress on the pyrite-phase,including FeO_(2),FeO_(2)H,and FeO_(2)Hx,which is critical for understanding the water cycling,redox equilibria,and compositional heterogenicities in the deep lower mantle.

关键词： Deep lower mantle Core-mantle boundary Pyrite-type phase Hydrogen-bearing phase

Structure, charge transfer, and superconductivity of M-doped phenanthrene(M = Al, Ga, and In): A comparative study of K-doped cases

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science China(Physics,Mechanics & Astronomy) 2019年第5期62卷 107-113页

作者： Hai-Yan Lv Guo-Hua Zhong Ming Chen Chun-Lei Yang Xiao-Jia Chen Hai-Qing Lin Shenzhen Institutes of advanced technology Chinese Academy of Sciences Nano science and technology Institute University of Science and Technology of China Beijing Computational science Research center center for high pressure science and technology advanced Research

Aromatic hydrocarbons doped with K have been shown to be potential high-temperature superconductors. To investigate the doping effects of trivalent metals(Al, Ga, and In) that have a smaller radii than K, we studied the crystal structure, stability,charge transfer, band structure, and superconductivity of trivalent metal-doped phenanthrene via first-principles *** with Al/Ga/In considerably differs from doping with K and cannot be simply regarded as a linear developmental change in the structural and electronic characteristics caused by a change in the valence electron numbers. Al/Ga/In atoms are difficult to dope into the intralayer region, and the charge transfer is close to zero, which is far less than the effect of K doping. We found that the metallization of the Al/Ga/In-doped system originates from the formation of gap states instead of charge transfer. The weak superconductivity obtained in the Al/Ga/In-doped system is also different from the K-doped system. These results are helpful in terms of understanding the structure and superconductivity of metal-doped aromatic superconductors.

关键词： phenanthrene aromatic hydrocarbons trivalent metals charge transfer superconductivity