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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

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

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

Enhancing reversibility of LiNi_(0.5)Mn_(1.5)O_(4)by regulating surface oxygen deficiency

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Carbon Energy 2023年第11期5卷 81-89页

作者： Dandan Wang Cong Gao Xuefeng Zhou Shang Peng Mingxue Tang Yonggang Wang Lujun Huang Wenge Yang Xiang Gao Center for High Pressure Science and Technology Advanced Research(hpstar) BeijingChina School of Materials Science and Engineering Harbin Institute of TechnologyHarbinChina

Oxygen deficiency has crucial effects on the crystal structure and electrochemical performance of spinel oxide lithium electrode materials such as LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)*** particular,the oxygen stoichiometry on the crystal surface differs from that on the crystal interior in *** detection of local oxygen loss in LNMO and its correlation with the crystal structure and the cycling stability of LNMO remain *** this study,the effect of oxygen deficiency in LNMO controlled by sintering temperature on the surface crystal structure and electrochemical performance of LNMO is comprehensively *** high concentration of oxygen vacancies segregates at the surface regions of LNMO forming a thin rock‐salt and/or deficient spinel surface *** atomic‐level surface structure reconstruction was demonstrated by annular dark‐field and annular brightfield *** the synthesis of LNMO,the higher sintering temperature results in higher crystallinity but the higher oxygen deficiency in *** high crystallinity of LNMO would increase the thermal stability of LNMO cathodes while the high content of oxygen deficiency would decrease the surface structural stability of ***,the LNMO sintered at a medium temperature of 850°C achieved the best capacity *** results suggest a competitive function mechanism between oxygen stoichiometry and the crystallinity of LNMO on the cycling performance of LNMO.

关键词： electrochemical performance LiNi_(0.5)Mn_(1.5)O_(4) lithium‐ion battery oxygen vacancies surface reconstruction

Deep oxygen cycle: Iron-rich Fe-O compounds at Earth's core pressures

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Deep oxygen cycle: Iron-rich Fe-O compounds at Earth's core ...

Realizing high thermoelectric properties in p-type polycrystalline SnSe by inducing DOS distortion

作者： Jin Liu hpstar

Oxygen is the most abundant element on Earth. While pervasive in the mantle, its presence in the core is still a subject of debate but critical to our understanding of the core-mantle co-evolution and geomagnetic fiel... 详细信息

关键词： Earth Deep oxygen cycle Iron-rich Fe-O compounds at Earth's core pressures

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Rare Metals 2021年第10期40卷 2819-2828页

作者： Yu-Ping Wang Bing-Chao Qin Dong-Yang Wang Tao Hong Xiang Gao Li-Dong Zhao School of Materials Science and Engineering Beihang UniversityBeijing 100191China Center for High Pressure Science and Technology Advanced Research(hpstar) Beijing 100094China

SnSe crystals have been discovered as one of the most efficient thermoelectric materials due to their remarkable thermal and electrical transports. But the polycrystalline SnSe possesses much lower performance especially for the low carrier mobility and electrical conductivity. We firstly attempted to explain and verify the difference in the electrical conductivity as a function of temperature between p-type crystalline and polycrystalline SnSe by considering the grain boundary effects in the polycrystalline samples. On the basis of 2% Na doping to optimize the carrier concentration, the carrier mobility is improved by further introducing In, leading to enhanced carrier mobility from 3 to 9 cm2·V^(-1)·s^(-1) in polycrystalline SnSe. Moreover, In doping introduces extra resonant levels in SnSe, which increases the density of states near Fermi level and leads to an enhanced band effective mass. Large Seebeck coefficient of ~205 l V·K^(-1) at 300 K and maximum power factor of ~7.5 l W·cm^(-1)·K^(-2) at 773 K can be obtained in the Sn_(0.975)Na_(0.02)In_(0.005) Se sample,leading to a competitively high dimensionless figure of merit(ZT) value exceeding 1.1 at 773 K.

关键词： Thermoelectric p-type polycrystalline SnSe Carrier mobility Resonant effect Band effective mass

Evolution of electrical conductivity and semiconductor to metal transition of iron oxides at extreme conditions

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Chinese Physics B 2022年第8期31卷 95-100页

作者： Yukai Zhuang Qingyang Hu Institute of Atomic and Molecular Physics Sichuan UniversityChengdu 610065China Center for High Pressure Science and Technology Advanced Research(hpstar) Beijing 100094China

Iron oxides are widely found as ores in Earth's crust and are also important constituents of its *** polymorphism,composition changes,and electronic structures play essential roles in controlling the structure and geodynamic properties of the solid *** all-natural occurring iron oxides are semiconductors or insulators at ambient pressure,they start to metalize under *** in this work,we review the electronic conductivity and metallization of iron oxides under high-pressure conditions found in Earth's lower *** summarize that the metallization of iron oxides is generally controlled by the pressure-induced bandgap closure near the Fermi *** metallization,they possess much higher electrical and thermal conductivity,which will facilitate the thermal convection,support a more stable and thicker D′′layer,and formulate Earth's magnetic field,all of which will constrain the large-scale dynamos of the mantle and core.

关键词： high pressure metallization iron oxides electrical conductivity

Pressure-driven symmetry breaking and electron disproportionation of the trigonal Nb_(3)cluster in Nb_(3)Cl_(8)

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Science China(Physics,Mechanics & Astronomy) 2022年第7期65卷 153-158页

作者： Zimin Jiang Dequan Jiang Yiming Wang Chen Li Ke Liu Ting Wen Fuyang Liu Zhengyang Zhou Yonggang Wang Center for High Pressure Science and Technology Advanced Research(hpstar) Beijing 100094China Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 201899China

Symmetry breaking of metal cluster-based strongly correlated systems can give rise to collective ***,the twodimensional Nb_(3) cluster compound Nb_(3)Cl_(8) is shown to suffer dramatic symmetry breaking and electron disproportionation under compression.A structural phase transition from trigonal P–3m1 to monoclinic C2/m is observed near 8 GPa with the three-fold symmetry *** disproportionation occurs on Nb_(3) clusters from delocalized Nb^(8/3+)Nb^(8/3+)Nb^(8/3+)to localized Nb^(3+)Nb^(3+)Nb^(2+),which results in a subtle bandgap discontinuity,as evidenced by electrical transport and UV-Vis absorption measurements.

关键词： Nb_(3)Cl_(8) symmetry breaking electron disproportionation layered semiconductor high pressure

Materials under pressure conditions studied by multiple synchrotron X-ray techniques and simulations

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Materials under pressure conditions studied by multiple sync...