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
The crystal structure and magnetic properties of SmFeg_xCox （x = 0, 1, 3, 5） alloys were studied by X-ray powder diffraction （XRD） and magnetic measurements. The Th2Znl7-type structure of the as-cast state is chan...The crystal structure and magnetic properties of SmFeg_xCox （x = 0, 1, 3, 5） alloys were studied by X-ray powder diffraction （XRD） and magnetic measurements. The Th2Znl7-type structure of the as-cast state is changed to TbCu7-type structure after quenching to a rotating molybdenum roll under certain velocity （12, 20, and 32 m.s-l）. The （002） XRD peak appears and ^-Fe phase disappears when the Co is added up to x = 5. Saturation magnetization of SmFe9 under different temperature shows 9 % change （112-102 A.m2.g-1） when the temperature is higher than 200 K. The saturation magnetization is 115 A.m2.g-1 and coercivity is 0.304 T at 5 K for SmFe9 alloys. Increased saturation magnetization and decreased coercivity can be obtained for Co added up to x = 5 at 5 K.展开更多
SmFe thin films were prepared by DC magietron sputtering at room temperature and 300 %. The influence of magnetic annealing temperature on the phase structure and magnetic properties was investigated. Results showed t...SmFe thin films were prepared by DC magietron sputtering at room temperature and 300 %. The influence of magnetic annealing temperature on the phase structure and magnetic properties was investigated. Results showed that thermal sputtering followed by a heat treatment process helped to obtain a structure with a relatively large fraction of SmFe2. Residual phases observed were α-Fe, Sm2O3, and unknown phases. During the annealing treatment, the intrinsic compressive stress in SmFe films was relieved and could become tensile at higher annealing temperatures. The degree of in-plane anisotropy weakened, and furthermore, the anisotropy transformed into out-of-plane anisotropy.展开更多
Compounds with the composition SmFex（x=3–8） were prepared by melt spun method at a velocity of 40 m/s and subsequent annealing at temperature between 600–1000 ℃. The crystal structures of the as-quenched and as a...Compounds with the composition SmFex（x=3–8） were prepared by melt spun method at a velocity of 40 m/s and subsequent annealing at temperature between 600–1000 ℃. The crystal structures of the as-quenched and as annealed powders were investigated by XRD methods with following Rietveld analysis. The glass forming ability could be enhanced by the increase of Sm content to x≤5.Metastable Sm5Fe17-type structure existed when 3≤x≤5 and temperature was lower than 800 ℃. SmFe2-type structure could be stable up to 1000 ℃ when x〉3 and temperature was under 800 ℃. The content of SmFe2-type decreased with the increase of x value and increased with temperature lower than 800 ℃, from which SmFe2-type started to bring the transition to SmFe3-type. As for Sm5Fe17-type compounds with x=3.4, the highest coercivity of 33.6 kOe could be obtained under a velocity of 30 m/s and heat treated under 700 ℃×1h.展开更多
Nanocrystalline SmFe_（8.95-x）Ga_（0.26）Nb_xN_δ（x=0, 0.1, 0.2, 0.3） were prepared using rapid-quenching,annealing and nitriding. The magnetic properties and crystal structures were systematically studied under va...Nanocrystalline SmFe_（8.95-x）Ga_（0.26）Nb_xN_δ（x=0, 0.1, 0.2, 0.3） were prepared using rapid-quenching,annealing and nitriding. The magnetic properties and crystal structures were systematically studied under various wheel velocities to investigate the influence of Nb doping for the compounds. It is found that TbCu7-type structure is able to be obtained even though the wheel velocity is reduced to 20 m/s（x = 0.3）. An significant increase（△T_c=70 ℃） of the Curie temperature is obtained with Nb doping at x = 0.1 due to the lattice expansion revealed by Rietveld analysis. The optimum coercivity with the value H_（cj） of 810 kA/m is achieved at x = 0.2 in the nitrides, in which a reasonable distribution of grain sizes of both TbCu_7-type SmFe_9 N_δ and α-Fe can be found. However, an excess of Nb doping may lead to the increase of the weight fraction of α-Fe, which in turn deteriorates the magnetic properties.展开更多
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.
基金financially supported by the National High Technology Research and Development Program of China(No.2011AA03A402)the International Scientific and Technological Cooperation Projects(No.2010DFB53520)
文摘The crystal structure and magnetic properties of SmFeg_xCox （x = 0, 1, 3, 5） alloys were studied by X-ray powder diffraction （XRD） and magnetic measurements. The Th2Znl7-type structure of the as-cast state is changed to TbCu7-type structure after quenching to a rotating molybdenum roll under certain velocity （12, 20, and 32 m.s-l）. The （002） XRD peak appears and ^-Fe phase disappears when the Co is added up to x = 5. Saturation magnetization of SmFe9 under different temperature shows 9 % change （112-102 A.m2.g-1） when the temperature is higher than 200 K. The saturation magnetization is 115 A.m2.g-1 and coercivity is 0.304 T at 5 K for SmFe9 alloys. Increased saturation magnetization and decreased coercivity can be obtained for Co added up to x = 5 at 5 K.
基金Project supported by the National Natural Science Foundation of China (50271017)
文摘SmFe thin films were prepared by DC magietron sputtering at room temperature and 300 %. The influence of magnetic annealing temperature on the phase structure and magnetic properties was investigated. Results showed that thermal sputtering followed by a heat treatment process helped to obtain a structure with a relatively large fraction of SmFe2. Residual phases observed were α-Fe, Sm2O3, and unknown phases. During the annealing treatment, the intrinsic compressive stress in SmFe films was relieved and could become tensile at higher annealing temperatures. The degree of in-plane anisotropy weakened, and furthermore, the anisotropy transformed into out-of-plane anisotropy.
基金supported by the National High Technology Research and Development Program of China(863 Program)(2011AA03A402)
文摘Compounds with the composition SmFex（x=3–8） were prepared by melt spun method at a velocity of 40 m/s and subsequent annealing at temperature between 600–1000 ℃. The crystal structures of the as-quenched and as annealed powders were investigated by XRD methods with following Rietveld analysis. The glass forming ability could be enhanced by the increase of Sm content to x≤5.Metastable Sm5Fe17-type structure existed when 3≤x≤5 and temperature was lower than 800 ℃. SmFe2-type structure could be stable up to 1000 ℃ when x〉3 and temperature was under 800 ℃. The content of SmFe2-type decreased with the increase of x value and increased with temperature lower than 800 ℃, from which SmFe2-type started to bring the transition to SmFe3-type. As for Sm5Fe17-type compounds with x=3.4, the highest coercivity of 33.6 kOe could be obtained under a velocity of 30 m/s and heat treated under 700 ℃×1h.
文摘Nanocrystalline SmFe_（8.95-x）Ga_（0.26）Nb_xN_δ（x=0, 0.1, 0.2, 0.3） were prepared using rapid-quenching,annealing and nitriding. The magnetic properties and crystal structures were systematically studied under various wheel velocities to investigate the influence of Nb doping for the compounds. It is found that TbCu7-type structure is able to be obtained even though the wheel velocity is reduced to 20 m/s（x = 0.3）. An significant increase（△T_c=70 ℃） of the Curie temperature is obtained with Nb doping at x = 0.1 due to the lattice expansion revealed by Rietveld analysis. The optimum coercivity with the value H_（cj） of 810 kA/m is achieved at x = 0.2 in the nitrides, in which a reasonable distribution of grain sizes of both TbCu_7-type SmFe_9 N_δ and α-Fe can be found. However, an excess of Nb doping may lead to the increase of the weight fraction of α-Fe, which in turn deteriorates the magnetic properties.
