[Hmim]_3PW_(12)O_(40) was developed and used in the acetalization of carbonyl compounds in excellent yields.The ionic liquidheteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separa...[Hmim]_3PW_(12)O_(40) was developed and used in the acetalization of carbonyl compounds in excellent yields.The ionic liquidheteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation.The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.展开更多
The structure and magnetic properties of Dy2AlFe12Mn4 compound have been investigated by means of X-ray diffraction and magnetization measurements. The Dy2AlFe12Mn4 compound has a hexagonal Th2Ni17-type structure. Neg...The structure and magnetic properties of Dy2AlFe12Mn4 compound have been investigated by means of X-ray diffraction and magnetization measurements. The Dy2AlFe12Mn4 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion was found in Dy2AlFe12Mn4 compound from 229 to 280 K by X-ray dilatometry. The coefficient of the average thermal expansion is α^- =-3.8×10^-5 K^-1. The magnetostrictive deformations from 105 to 270 K have been calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωs decreases from 6.2 × 10^-3 to near zero with the temperature increasing from 105 to 270 K, the spontaneous linear magnetostrictive deformation λc along the c axis is much larger than the spontaneous linear magnetostrictive deformation λa in basal-plane at the same temperature except close to 249 K.展开更多
The effect of substitution of Mn on the structure and magnetic properties of HoFe 12- x Mn x (x =2 0, 3 0, 4 0 and 5 0) compounds was investigated. All the HoFe 12x Mn x compounds studied cry...The effect of substitution of Mn on the structure and magnetic properties of HoFe 12- x Mn x (x =2 0, 3 0, 4 0 and 5 0) compounds was investigated. All the HoFe 12x Mn x compounds studied crystallize in ThMn 12 type of structure. The lattice constants and unit cell volume increase monotonously with increasing Mn concentration. The Curie temperature and the moments of the transition metal sublattice of HoFe 12- x Mn x compounds decrease monotonously with increasing Mn content. A minimum appears at x =3 0 in the Mn concentration dependence of the saturation magnetization of HoFe 12- x Mn x compounds. A compensation point appears in the M(t) curve of the compound with x =4 0. The mean field constant n RT of HoFe 9Mn 3 was calculated.展开更多
The structure and intrinsic magnetic properties of RFeM(M=V or Ti),type 1:12,have been studied by magnetic measurement and X-ray diffraction.They are body-centered tetragonal ThMn_(12)structure.The changes of crystal ...The structure and intrinsic magnetic properties of RFeM(M=V or Ti),type 1:12,have been studied by magnetic measurement and X-ray diffraction.They are body-centered tetragonal ThMn_(12)structure.The changes of crystal lattice constants coincide with that of their element radii.Curie temperature is decided mainly by the exchange interactions of 3d-3d and 3d-4f atom pairs.The data obtained by mean-field approximation agree well with experimental values.The magnetic moment coupling in these compounds for LRE is ferromagnetic,and for HRE is antiferromagnetic.At low temperature,anisotropy field is decided by RE sublattice.In this paper,the influence of magnetic properties of cobalt and nickel replacing iron has also been studied.展开更多
The space group of PrCo_(12)B_6,compound has been determined using the convergent beam elec- tron diffraction method.The space group is found to be R3m.
基金support from Nanjing University of Science and Technology
文摘[Hmim]_3PW_(12)O_(40) was developed and used in the acetalization of carbonyl compounds in excellent yields.The ionic liquidheteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation.The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.
基金This project was financially supported by the National Natural Science Foundation of China (No. 50271022)the Excellent Yong Teachers Program ofMOE of China (No. 1999), and the Natural Science Foundation of Tianjin City (No. 043602011).]
文摘The structure and magnetic properties of Dy2AlFe12Mn4 compound have been investigated by means of X-ray diffraction and magnetization measurements. The Dy2AlFe12Mn4 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion was found in Dy2AlFe12Mn4 compound from 229 to 280 K by X-ray dilatometry. The coefficient of the average thermal expansion is α^- =-3.8×10^-5 K^-1. The magnetostrictive deformations from 105 to 270 K have been calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωs decreases from 6.2 × 10^-3 to near zero with the temperature increasing from 105 to 270 K, the spontaneous linear magnetostrictive deformation λc along the c axis is much larger than the spontaneous linear magnetostrictive deformation λa in basal-plane at the same temperature except close to 249 K.
文摘The effect of substitution of Mn on the structure and magnetic properties of HoFe 12- x Mn x (x =2 0, 3 0, 4 0 and 5 0) compounds was investigated. All the HoFe 12x Mn x compounds studied crystallize in ThMn 12 type of structure. The lattice constants and unit cell volume increase monotonously with increasing Mn concentration. The Curie temperature and the moments of the transition metal sublattice of HoFe 12- x Mn x compounds decrease monotonously with increasing Mn content. A minimum appears at x =3 0 in the Mn concentration dependence of the saturation magnetization of HoFe 12- x Mn x compounds. A compensation point appears in the M(t) curve of the compound with x =4 0. The mean field constant n RT of HoFe 9Mn 3 was calculated.
基金This work is supported in part by the Magnetics Open Laboratory of Academia Sinica.
文摘The structure and intrinsic magnetic properties of RFeM(M=V or Ti),type 1:12,have been studied by magnetic measurement and X-ray diffraction.They are body-centered tetragonal ThMn_(12)structure.The changes of crystal lattice constants coincide with that of their element radii.Curie temperature is decided mainly by the exchange interactions of 3d-3d and 3d-4f atom pairs.The data obtained by mean-field approximation agree well with experimental values.The magnetic moment coupling in these compounds for LRE is ferromagnetic,and for HRE is antiferromagnetic.At low temperature,anisotropy field is decided by RE sublattice.In this paper,the influence of magnetic properties of cobalt and nickel replacing iron has also been studied.
文摘The space group of PrCo_(12)B_6,compound has been determined using the convergent beam elec- tron diffraction method.The space group is found to be R3m.
