The local electronic structure and magnetic properties of GaAs doped with 3d transition metal (Sc, Ti, V, Cr, Mn, Fe, Co, Ni) were studied by using discrete variational method (DVM) based on density functional theory....The local electronic structure and magnetic properties of GaAs doped with 3d transition metal (Sc, Ti, V, Cr, Mn, Fe, Co, Ni) were studied by using discrete variational method (DVM) based on density functional theory. The calculated result indicated that the magnetic moment of transition metal increases first and then decreases, and reaches the maximum value when Mn is doped into GaAs. In the case of Mn concentration of 1.4%, the magnetic moment of Mn is in good agreement with the experimental result. The coupling between impure atoms in the system with two impure atoms was found to have obvious variation. For different transition metal, the coupling between the impure atom and the nearest neighbor As also has different variation.展开更多
The static polarizabilities and the second-order hyperpolarizabilities of a series of tri-nuclear metal cluster models MS4(MPPh3)2(MPPh3) (M=Mo,W; M=Cu, Ag, Au) have been calculated within the first-principle theoreti...The static polarizabilities and the second-order hyperpolarizabilities of a series of tri-nuclear metal cluster models MS4(MPPh3)2(MPPh3) (M=Mo,W; M=Cu, Ag, Au) have been calculated within the first-principle theoretical framework. The model clusters have two fragments of rhombic units and it is the charge transfer from one of these moieties to the other that is responsible for nonlinear optical property. This kind of electronic delocalization, differentiated from that of planar p-system, is very interesting and is worthy for further investigation.展开更多
Atomistic characterization of chemical element distribution is crucial to understanding the role of alloying elements for strengthening mechanism of superalloy. In the present work, the site preferences of two alloyin...Atomistic characterization of chemical element distribution is crucial to understanding the role of alloying elements for strengthening mechanism of superalloy. In the present work, the site preferences of two alloying elements X -Y in γ-Ni of Ni-based superalloy are systematically studied using first-principles calculations with and without spin-polarization. The doping elements X and Y are chosen from the 27 kinds of 3 d, 4 d, 5 d group transition metals（Sc, Ti, V, Cr, Mn, Fe, Co,Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au） and Al. We find that the spin-polarized calculations for Re-Re, Re-Ru, Re-Cr, Ru-Cr show a strong chemical binding affinity between the solute elements and are more consistent with the experimental results. The binding energies of pairs between the 28 elements have an obvious periodicity and are closely related the electronic configuration of the elements. When the d-electrons of the element are close to the half full-shell state, two alloying elements possess attractive binding energies, reflecting the effect of the Hund＇s rule. The combinations of early transition metals（Sc, Ti, V, Y, Zr, Nb, Hf, Ta） have a repulsive interaction in γ-Ni. These results offer insights into the role of alloying elements for strengthening mechanism of superalloy.展开更多
The new chiral cluster [NiRuMo(CO)5(m3-S)(h5-C5H5)(h5-C5H4COCH3)] 3 was synthesized by the reaction of precursor [CoRuMo(CO)8(m3-S)(h5-C5H4COCH3)] 1 with NiCp2 2 in refluxing THF. It was characterized by C/H elemental...The new chiral cluster [NiRuMo(CO)5(m3-S)(h5-C5H5)(h5-C5H4COCH3)] 3 was synthesized by the reaction of precursor [CoRuMo(CO)8(m3-S)(h5-C5H4COCH3)] 1 with NiCp2 2 in refluxing THF. It was characterized by C/H elemental analysis, IR and 1H NMR. Molecular structure of cluster 3 was determined by single-crystal X-ray analyses. Crystal data: triclinic, space group P with the following crystallographic parameters: a = 7.9606(8), b = 8.5604(9), c = 14.779(2) , a = 93.908(2), b = 105.057(2), g = 101.463(2)? C17H12O6MoNiRuS, Mr = 600.05, Z = 2, V = 945.5(2) 3, Dc = 2.108 g/cm3, m = 2.568 mm-1, (2q )max ≤ 56.48, F(000) = 584,the final R = 0.0380 and wR = 0.0674 for 2995 observed reflections with I > 2.00s(I).展开更多
The performance of electrocatalytic oxygen reduction on Mo-Ru-X (X=S, Se, Te) was investigated. The catalysts were synthesized by the carbonyl complexes decomposition method. The activities of the catalysts were measu...The performance of electrocatalytic oxygen reduction on Mo-Ru-X (X=S, Se, Te) was investigated. The catalysts were synthesized by the carbonyl complexes decomposition method. The activities of the catalysts were measured by potentiodynamic and AC impedance. The micro-structures and compositions were characterized by XRD, TEM and EDS. Transmission electron microscopy (TEM) measurements reveal that the catalyst material is of amorphous Ru cluster chalcogenides in the nanoscale range. The electrochemical experiments show that the activity of Mo-Ru-Se is the highest, and peak current density is 3.32 mA·cm-2. However, Mo-Ru-Se is sensitive to methanol in methanol-containing electrolyte, and the activity decreased with the increasing of methanol concentration. The activity of Mo-Ru-S is poorer than Mo-Ru-Se, the peak current density is 2.80 mA·cm-2, the behavior of methanol effect on the activity is similar to Mo-Ru-Se. The tolerant-methanol performance of Mo-Ru-Te is the best in the three, but activity is not high, peak current density is 2.69 mA·cm-2 only.展开更多
基金the National Natural Science Foundation of China(Grant No.10347010)
文摘The local electronic structure and magnetic properties of GaAs doped with 3d transition metal (Sc, Ti, V, Cr, Mn, Fe, Co, Ni) were studied by using discrete variational method (DVM) based on density functional theory. The calculated result indicated that the magnetic moment of transition metal increases first and then decreases, and reaches the maximum value when Mn is doped into GaAs. In the case of Mn concentration of 1.4%, the magnetic moment of Mn is in good agreement with the experimental result. The coupling between impure atoms in the system with two impure atoms was found to have obvious variation. For different transition metal, the coupling between the impure atom and the nearest neighbor As also has different variation.
基金supported by the National Natural Science Foundation of China(NSFC.69978021 and 20173064)FPNSFC(E9910030).
文摘The static polarizabilities and the second-order hyperpolarizabilities of a series of tri-nuclear metal cluster models MS4(MPPh3)2(MPPh3) (M=Mo,W; M=Cu, Ag, Au) have been calculated within the first-principle theoretical framework. The model clusters have two fragments of rhombic units and it is the charge transfer from one of these moieties to the other that is responsible for nonlinear optical property. This kind of electronic delocalization, differentiated from that of planar p-system, is very interesting and is worthy for further investigation.
基金Project supported by the National Key R&D Program of China(Grant Nos.2017YFB0701501,2017YFB0701502,and 2017YFB0701503)
文摘Atomistic characterization of chemical element distribution is crucial to understanding the role of alloying elements for strengthening mechanism of superalloy. In the present work, the site preferences of two alloying elements X -Y in γ-Ni of Ni-based superalloy are systematically studied using first-principles calculations with and without spin-polarization. The doping elements X and Y are chosen from the 27 kinds of 3 d, 4 d, 5 d group transition metals（Sc, Ti, V, Cr, Mn, Fe, Co,Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au） and Al. We find that the spin-polarized calculations for Re-Re, Re-Ru, Re-Cr, Ru-Cr show a strong chemical binding affinity between the solute elements and are more consistent with the experimental results. The binding energies of pairs between the 28 elements have an obvious periodicity and are closely related the electronic configuration of the elements. When the d-electrons of the element are close to the half full-shell state, two alloying elements possess attractive binding energies, reflecting the effect of the Hund＇s rule. The combinations of early transition metals（Sc, Ti, V, Y, Zr, Nb, Hf, Ta） have a repulsive interaction in γ-Ni. These results offer insights into the role of alloying elements for strengthening mechanism of superalloy.
基金This work was supported by the National Natural Science Foundation of China(29871061)
文摘The new chiral cluster [NiRuMo(CO)5(m3-S)(h5-C5H5)(h5-C5H4COCH3)] 3 was synthesized by the reaction of precursor [CoRuMo(CO)8(m3-S)(h5-C5H4COCH3)] 1 with NiCp2 2 in refluxing THF. It was characterized by C/H elemental analysis, IR and 1H NMR. Molecular structure of cluster 3 was determined by single-crystal X-ray analyses. Crystal data: triclinic, space group P with the following crystallographic parameters: a = 7.9606(8), b = 8.5604(9), c = 14.779(2) , a = 93.908(2), b = 105.057(2), g = 101.463(2)? C17H12O6MoNiRuS, Mr = 600.05, Z = 2, V = 945.5(2) 3, Dc = 2.108 g/cm3, m = 2.568 mm-1, (2q )max ≤ 56.48, F(000) = 584,the final R = 0.0380 and wR = 0.0674 for 2995 observed reflections with I > 2.00s(I).
文摘The performance of electrocatalytic oxygen reduction on Mo-Ru-X (X=S, Se, Te) was investigated. The catalysts were synthesized by the carbonyl complexes decomposition method. The activities of the catalysts were measured by potentiodynamic and AC impedance. The micro-structures and compositions were characterized by XRD, TEM and EDS. Transmission electron microscopy (TEM) measurements reveal that the catalyst material is of amorphous Ru cluster chalcogenides in the nanoscale range. The electrochemical experiments show that the activity of Mo-Ru-Se is the highest, and peak current density is 3.32 mA·cm-2. However, Mo-Ru-Se is sensitive to methanol in methanol-containing electrolyte, and the activity decreased with the increasing of methanol concentration. The activity of Mo-Ru-S is poorer than Mo-Ru-Se, the peak current density is 2.80 mA·cm-2, the behavior of methanol effect on the activity is similar to Mo-Ru-Se. The tolerant-methanol performance of Mo-Ru-Te is the best in the three, but activity is not high, peak current density is 2.69 mA·cm-2 only.
