Chrom-pyroaurite, associated with serpentine, chromite, magnetite, ehaleopyrite,pyrite and etc., is found in serpentinite in Southwestern China. Its coiour is violet in aggregate, but colorless or pale pink in thin fr...Chrom-pyroaurite, associated with serpentine, chromite, magnetite, ehaleopyrite,pyrite and etc., is found in serpentinite in Southwestern China. Its coiour is violet in aggregate, but colorless or pale pink in thin fragments. The mineral is transparent with glassy luster. Specific gravity 2.12±0.01 (determined by s.g. bottle).Hardness 1--1.5. It occurs in massive aggregate and is of apparent greasy feel. Under microscope it has scaly and fibrous appearance. Pleochroism is not clear with N.--colorless, No--pale pink. Uniaxial negative. No = 1.5560, N, = 1.5450, No -- N4=0.011. Apparent endothermic peaks are noticed at 270° and 460℃ respectively.Chemical composition is gaven as: MgO 36.74, 35.62; FeO 0.1, 0.15; MuO 0.06, 0.01;Fe2O3 13.54, 12.79; Cr2O3 6.94, 7.49; Al2O3 2.21, 1.74; CO2 6.45, 7.78; H2O^+ 32.33, 32.30;H2O^- 2.38, 1.78; total 100.75, 100.56. The mineral belongs to trigonal system, α0=6.165A, c0= 46.760A, c0/α0 = 7.585. Cell dimension V= 1537A^3, Z = 3. Strongest Xray pattern lines are 10.48(8), 8.56(5), 7.8(10), 5.12(4), 3.89(10), 2.60(5), 1.99(6).The mineral is named after its eomposition.展开更多
Most of volatile organic compounds （VOCs） are harmful to the atmosphere and human health. Cata‐lytic combustion is an effective way to eliminate VOCs. The key issue is the availability of high per‐formance catalys...Most of volatile organic compounds （VOCs） are harmful to the atmosphere and human health. Cata‐lytic combustion is an effective way to eliminate VOCs. The key issue is the availability of high per‐formance catalysts. Many catalysts including transition metal oxides, mixed metal oxides, and sup‐ported noble metals have been developed. Among these catalysts, the porous ones attract much attention. In this review, we focus on recent advances in the synthesis of ordered mesoporous and macroporous transition metal oxides, perovskites, and supported noble metal catalysts and their catalytic oxidation of VOCs. The porous catalysts outperformed their bulk counterparts. This excel‐lent catalytic performance was due to their high surface areas, high concentration of adsorbed oxy‐gen species, low temperature reducibility, strong interaction between noble metal and support and highly dispersed noble metal nanoparticles and unique porous structures. Catalytic oxidation of carbon monoxide over typical catalysts was also discussed. We made conclusive remarks and pro‐posed future work for the removal of VOCs.展开更多
Metal-rich transition metal sulfides recently gained increasing attention as electrocatalysts for the hydrogen evolution reaction(HER),as they are capable to overcome major challenges faced by sulfide-rich metal catal...Metal-rich transition metal sulfides recently gained increasing attention as electrocatalysts for the hydrogen evolution reaction(HER),as they are capable to overcome major challenges faced by sulfide-rich metal catalysts such as limited conductivity and the necessity of nanostructuring.Herein,we present the synthesis,characterization and electrocatalytic investigation of ternary metal-rich sulfide composites FexCo9-xS8 as well as Ni_(y)Co_(9-y)S_(8)(x=y=0-4.5),which possess pentlandite-type structures.In this study,we show a stepwise alteration of the binary cobalt pentlandite Co9S8 and report on the replacement of cobalt with up to 4.5 equivalents of either iron or nickel.These altered pentlandite composites facilitate the proton reduction in acidic media at different temperatures.We furthermore show that the stoichiometric variation has a decisive influence on the electrochemical activation/deactivation behavior of the catalysts under reductive electrocatalytic conditions.Here,Co-deficient composites display an improved HER performance in contrast to Co_(9)S_(8).Notably,Ni/Co compounds generally tend to show higher catalytic activities towards HER than their respective Fe/Co compounds.展开更多
There are potentially huge amounts of water stored in Earth's mantle, and the water solubilities in the silicate minerals range from tens to thousands of part per minion(ppm, part per million). Exploring water in ...There are potentially huge amounts of water stored in Earth's mantle, and the water solubilities in the silicate minerals range from tens to thousands of part per minion(ppm, part per million). Exploring water in the mantle has attracted much attention from the societies of mineralogy and geophysics in recent years. In the subducting slab, serpentine breaks down at high temperature, generating a series of dense hydrous magnesium silicate(DHMS) phases, such as phase A, chondrodite, clinohumite, etc. These phases may serve as carriers of water as hydroxyl into the upper mantle and the mantle transition zone(MTZ). On the other hand, wadsleyite and ringwoodite, polymorphs of olivine, are most the abundant minerals in the MTZ, and able to absorb significant amount of water(up to about 3 wt.% H_2O). Hence, the MTZ becomes a very important layer for water storage in the mantle, and hydration plays important roles in physics and chemistry of the MTZ. In this paper, we will discuss two aspects of hydrous silicate minerals:(1) crystal structures and(2) equations of state(Eo Ss).展开更多
Perovskite manganites show exotic functionalities due to the coupling between spin, charge, orbital and lattice, such as metal-insulator transition, colossal magnetoresistance （ CMR ） , charge-orbital order and phas...Perovskite manganites show exotic functionalities due to the coupling between spin, charge, orbital and lattice, such as metal-insulator transition, colossal magnetoresistance （ CMR ） , charge-orbital order and phase separation. Recently, an extraordinary anisotropic magnetoresistance （ AMR ） has been observed in perovskite manganite single crystals. The AMR value is about 2 orders larger than that of the conventional 3E transition metals and alloys, which is attributed to tunable metal-insulator transition temperature modulated by the magnetic field. This result provides a new route for exploring novel AMR materials and their applications.展开更多
文摘Chrom-pyroaurite, associated with serpentine, chromite, magnetite, ehaleopyrite,pyrite and etc., is found in serpentinite in Southwestern China. Its coiour is violet in aggregate, but colorless or pale pink in thin fragments. The mineral is transparent with glassy luster. Specific gravity 2.12±0.01 (determined by s.g. bottle).Hardness 1--1.5. It occurs in massive aggregate and is of apparent greasy feel. Under microscope it has scaly and fibrous appearance. Pleochroism is not clear with N.--colorless, No--pale pink. Uniaxial negative. No = 1.5560, N, = 1.5450, No -- N4=0.011. Apparent endothermic peaks are noticed at 270° and 460℃ respectively.Chemical composition is gaven as: MgO 36.74, 35.62; FeO 0.1, 0.15; MuO 0.06, 0.01;Fe2O3 13.54, 12.79; Cr2O3 6.94, 7.49; Al2O3 2.21, 1.74; CO2 6.45, 7.78; H2O^+ 32.33, 32.30;H2O^- 2.38, 1.78; total 100.75, 100.56. The mineral belongs to trigonal system, α0=6.165A, c0= 46.760A, c0/α0 = 7.585. Cell dimension V= 1537A^3, Z = 3. Strongest Xray pattern lines are 10.48(8), 8.56(5), 7.8(10), 5.12(4), 3.89(10), 2.60(5), 1.99(6).The mineral is named after its eomposition.
基金supported by the National High Technology Research and Development Program (863 Program,2015AA034603)the National Natural Science Foundation of China (21377008,201077007,20973017)+1 种基金Foundation on the Creative Research Team Construction Promotion Project of Beijing Municipal InstitutionsScientific Research Base Construction-Science and Technology Creation Platform National Materials Research Base Construction~~
文摘Most of volatile organic compounds （VOCs） are harmful to the atmosphere and human health. Cata‐lytic combustion is an effective way to eliminate VOCs. The key issue is the availability of high per‐formance catalysts. Many catalysts including transition metal oxides, mixed metal oxides, and sup‐ported noble metals have been developed. Among these catalysts, the porous ones attract much attention. In this review, we focus on recent advances in the synthesis of ordered mesoporous and macroporous transition metal oxides, perovskites, and supported noble metal catalysts and their catalytic oxidation of VOCs. The porous catalysts outperformed their bulk counterparts. This excel‐lent catalytic performance was due to their high surface areas, high concentration of adsorbed oxy‐gen species, low temperature reducibility, strong interaction between noble metal and support and highly dispersed noble metal nanoparticles and unique porous structures. Catalytic oxidation of carbon monoxide over typical catalysts was also discussed. We made conclusive remarks and pro‐posed future work for the removal of VOCs.
文摘Metal-rich transition metal sulfides recently gained increasing attention as electrocatalysts for the hydrogen evolution reaction(HER),as they are capable to overcome major challenges faced by sulfide-rich metal catalysts such as limited conductivity and the necessity of nanostructuring.Herein,we present the synthesis,characterization and electrocatalytic investigation of ternary metal-rich sulfide composites FexCo9-xS8 as well as Ni_(y)Co_(9-y)S_(8)(x=y=0-4.5),which possess pentlandite-type structures.In this study,we show a stepwise alteration of the binary cobalt pentlandite Co9S8 and report on the replacement of cobalt with up to 4.5 equivalents of either iron or nickel.These altered pentlandite composites facilitate the proton reduction in acidic media at different temperatures.We furthermore show that the stoichiometric variation has a decisive influence on the electrochemical activation/deactivation behavior of the catalysts under reductive electrocatalytic conditions.Here,Co-deficient composites display an improved HER performance in contrast to Co_(9)S_(8).Notably,Ni/Co compounds generally tend to show higher catalytic activities towards HER than their respective Fe/Co compounds.
基金supported by the National Natural Science Foundation of China(Grant Nos.41590621&41473058)the Fundamental Research Funds for the Central University(Grant No.G1323531512)MOST Special Fund from the State Key Laboratory of Geological Processes and Mineral Resources(Grant No.MSFGPMR07),China University of Geosciences at Wuhan
文摘There are potentially huge amounts of water stored in Earth's mantle, and the water solubilities in the silicate minerals range from tens to thousands of part per minion(ppm, part per million). Exploring water in the mantle has attracted much attention from the societies of mineralogy and geophysics in recent years. In the subducting slab, serpentine breaks down at high temperature, generating a series of dense hydrous magnesium silicate(DHMS) phases, such as phase A, chondrodite, clinohumite, etc. These phases may serve as carriers of water as hydroxyl into the upper mantle and the mantle transition zone(MTZ). On the other hand, wadsleyite and ringwoodite, polymorphs of olivine, are most the abundant minerals in the MTZ, and able to absorb significant amount of water(up to about 3 wt.% H_2O). Hence, the MTZ becomes a very important layer for water storage in the mantle, and hydration plays important roles in physics and chemistry of the MTZ. In this paper, we will discuss two aspects of hydrous silicate minerals:(1) crystal structures and(2) equations of state(Eo Ss).
基金supported by National Natural Science Foundation of China(10874192)
文摘Perovskite manganites show exotic functionalities due to the coupling between spin, charge, orbital and lattice, such as metal-insulator transition, colossal magnetoresistance （ CMR ） , charge-orbital order and phase separation. Recently, an extraordinary anisotropic magnetoresistance （ AMR ） has been observed in perovskite manganite single crystals. The AMR value is about 2 orders larger than that of the conventional 3E transition metals and alloys, which is attributed to tunable metal-insulator transition temperature modulated by the magnetic field. This result provides a new route for exploring novel AMR materials and their applications.
