The electronic structures of rare earth cluster halides R(R_6X_(12)) and their interstitial compounds R_7X_(12)Z were studied by the DV-X_(?) method (R=Sc,Y,Pr,Gd or Er;X=Cl,Br or I;Z=B,C,N,Fe,Co or Ru).The results sh...The electronic structures of rare earth cluster halides R(R_6X_(12)) and their interstitial compounds R_7X_(12)Z were studied by the DV-X_(?) method (R=Sc,Y,Pr,Gd or Er;X=Cl,Br or I;Z=B,C,N,Fe,Co or Ru).The results show that because f electrons in empty rare earth cluster are screened,their orbitals are more difficult to overlap each other,a deficiency of skeleton orbitals in cluster causing the system to be unstable.They are easily condensed into chain compound R_2X_3 or R_5X_8.If a light atom of main group is embedded into octahedral cluster,bonding orbitals formed from interstitial atom and rare earth cluster strengthen cluster skeleton bond in the system to reach structural stability.If embedded atom belongs to transition metal,bonding orbitals composed of that of interstitial atom and rare earth cluster take the place of original cluster skeleton orbitals to form heteronuclear metal cluster (or double-coordination compound).展开更多
The magnetic properties and magnetocaloric effect in Fe4MnSi3B~ compounds with x=0, 0.05, 0.10, 0.15, 0.20, 0.25 have been investigated. X-ray diffraction study shows that all these compounds investigated crystallize ...The magnetic properties and magnetocaloric effect in Fe4MnSi3B~ compounds with x=0, 0.05, 0.10, 0.15, 0.20, 0.25 have been investigated. X-ray diffraction study shows that all these compounds investigated crystallize in the MnsSi3-type structure with space group P63/mcm. Boron insertion in the host ternary silicide Fe4MnSi3 does not change the crystal symmetry, only leads to an increase of the lattice parameters, indicating the B atoms entered the interstitial sites. With increasing B content, the Curie temperature shifts to higher temperatures. The maximal magnetic-entropy changes of the Fe4MnSi3Bx compounds with x=0, 0.10 and 0.20 are about 1.8 J/（kg.K）, 1.8 J/（kg-K） and 1.6 J/（kg.K）, respectively, for a field change from 0 to 1.5 T.展开更多
The development of highly active and easily coupled non-noble metal electrocatalysts for oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is of great significance for the H_(2) production by water ele...The development of highly active and easily coupled non-noble metal electrocatalysts for oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is of great significance for the H_(2) production by water electrolysis.Here,we have shown an anion-modulated HER and OER activity of 1D Co-Mo based interstitial compound heterojunctions for effective overall water splitting.The Co-Mo based complex nanowires from a one-pot route with high yields can be converted into MoC-Co heterojunction nanowires under N_(2) atmosphere,while a pyrolysis under NH_(3) can give CoMoN-CoN heterostructures.The work function revealed Mott-Schottky effect between interfaces of two heterostructures,which can introduce electron redistribution and thus promote the HER/OER process.The MoC-Co heterojunction nanowires delivers good HER activity at a low overpotential of 39mV to afford a current density of 10mA/cm^(2).Density functional theory calculations show that the heterogeneous interface formed between the Co and MoC optimizes the hydrogen adsorption free energy.Concurrently,CoMoN-CoN heterojunction nanowires exhibits good OER performance with a low overpotential of 260mV to reach 10mA/cm^(2),being superior to RuO_(2).The two catalysts can be coupled to assemble a two-electrode cell with a solarto-hydrogen efficiency of 12.3%at 1.54 V.This work provides an effective means to design easily coupled HER and OER catalysts for H_(2) production by water electrolysis.展开更多
The effect of nitridation process, i.e. temperature and time, on crystal structure and magnetic properties of SmFe9Nx inter- stitial compounds was systematically investigated. After nitridation treatment, nitrogen ato...The effect of nitridation process, i.e. temperature and time, on crystal structure and magnetic properties of SmFe9Nx inter- stitial compounds was systematically investigated. After nitridation treatment, nitrogen atoms were incorporated into SmFe9 alloys to form SnaFe9Nx interstitial compounds, which increased the distance of Fe-Fe and enhanced Fe-Fe interaction. As a result, SmFe9Nx interstitial compounds had a higher Curie temperature and more excellent magnetic properties than SmFe9 alloys. The relationships between nitridation temperature, nitridation time, nitriding efficiency, magnetic properties and phase transition were researched. It could be concluded that nitriding efficiency was strongly associated with magnetic properties and phase transition at different tem- peratures. The nitriding efficiency also had a connection with magnetic properties under different time, while no obvious phase transi- tion was found during that process. By studying nitridation process under a series of temperatures and time in this experiment, a suit- able nitridation temperature （713 K） and an ideal length of nitridation time （8 h） was decided, which would produce the optimal mag- netic behavior of SmFegNx interstitial compounds.展开更多
基金The project supported by the National Natural Science Foundation of China
文摘The electronic structures of rare earth cluster halides R(R_6X_(12)) and their interstitial compounds R_7X_(12)Z were studied by the DV-X_(?) method (R=Sc,Y,Pr,Gd or Er;X=Cl,Br or I;Z=B,C,N,Fe,Co or Ru).The results show that because f electrons in empty rare earth cluster are screened,their orbitals are more difficult to overlap each other,a deficiency of skeleton orbitals in cluster causing the system to be unstable.They are easily condensed into chain compound R_2X_3 or R_5X_8.If a light atom of main group is embedded into octahedral cluster,bonding orbitals formed from interstitial atom and rare earth cluster strengthen cluster skeleton bond in the system to reach structural stability.If embedded atom belongs to transition metal,bonding orbitals composed of that of interstitial atom and rare earth cluster take the place of original cluster skeleton orbitals to form heteronuclear metal cluster (or double-coordination compound).
基金supported by the National Natural Science Foundation of China (GrantNo.50661004)the Graduate Student Foundation of Inner Mongolia Normal University (No.YJSZD07002)partially supported by the scientific exchange program between the Netherlands and China
文摘The magnetic properties and magnetocaloric effect in Fe4MnSi3B~ compounds with x=0, 0.05, 0.10, 0.15, 0.20, 0.25 have been investigated. X-ray diffraction study shows that all these compounds investigated crystallize in the MnsSi3-type structure with space group P63/mcm. Boron insertion in the host ternary silicide Fe4MnSi3 does not change the crystal symmetry, only leads to an increase of the lattice parameters, indicating the B atoms entered the interstitial sites. With increasing B content, the Curie temperature shifts to higher temperatures. The maximal magnetic-entropy changes of the Fe4MnSi3Bx compounds with x=0, 0.10 and 0.20 are about 1.8 J/（kg.K）, 1.8 J/（kg-K） and 1.6 J/（kg.K）, respectively, for a field change from 0 to 1.5 T.
基金support of this research by the National Natural Science Foundation of China(No.91961111)the Natural Science Foundation of Heilongjiang Province(No.ZD2021B003)Fundamental Research Funds for the Central Universities(No.2572022BU05).
文摘The development of highly active and easily coupled non-noble metal electrocatalysts for oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is of great significance for the H_(2) production by water electrolysis.Here,we have shown an anion-modulated HER and OER activity of 1D Co-Mo based interstitial compound heterojunctions for effective overall water splitting.The Co-Mo based complex nanowires from a one-pot route with high yields can be converted into MoC-Co heterojunction nanowires under N_(2) atmosphere,while a pyrolysis under NH_(3) can give CoMoN-CoN heterostructures.The work function revealed Mott-Schottky effect between interfaces of two heterostructures,which can introduce electron redistribution and thus promote the HER/OER process.The MoC-Co heterojunction nanowires delivers good HER activity at a low overpotential of 39mV to afford a current density of 10mA/cm^(2).Density functional theory calculations show that the heterogeneous interface formed between the Co and MoC optimizes the hydrogen adsorption free energy.Concurrently,CoMoN-CoN heterojunction nanowires exhibits good OER performance with a low overpotential of 260mV to reach 10mA/cm^(2),being superior to RuO_(2).The two catalysts can be coupled to assemble a two-electrode cell with a solarto-hydrogen efficiency of 12.3%at 1.54 V.This work provides an effective means to design easily coupled HER and OER catalysts for H_(2) production by water electrolysis.
基金Project supported by National High Technology Research and Development Program of China （863 Program） （2011AA03A402） and the International Scientific and Technological Cooperation Project （2010DFB53520）
文摘The effect of nitridation process, i.e. temperature and time, on crystal structure and magnetic properties of SmFe9Nx inter- stitial compounds was systematically investigated. After nitridation treatment, nitrogen atoms were incorporated into SmFe9 alloys to form SnaFe9Nx interstitial compounds, which increased the distance of Fe-Fe and enhanced Fe-Fe interaction. As a result, SmFe9Nx interstitial compounds had a higher Curie temperature and more excellent magnetic properties than SmFe9 alloys. The relationships between nitridation temperature, nitridation time, nitriding efficiency, magnetic properties and phase transition were researched. It could be concluded that nitriding efficiency was strongly associated with magnetic properties and phase transition at different tem- peratures. The nitriding efficiency also had a connection with magnetic properties under different time, while no obvious phase transi- tion was found during that process. By studying nitridation process under a series of temperatures and time in this experiment, a suit- able nitridation temperature （713 K） and an ideal length of nitridation time （8 h） was decided, which would produce the optimal mag- netic behavior of SmFegNx interstitial compounds.
