In this article,we report on the magnetic structure of DyFe11Ti and its thermal evolution as probed by neutron powder diffraction.A thermodiffraction technique was used to follow the temperature dependence of the magn...In this article,we report on the magnetic structure of DyFe11Ti and its thermal evolution as probed by neutron powder diffraction.A thermodiffraction technique was used to follow the temperature dependence of the magnetic moments,as well as their orientation.The Dy and Fe moments were coupled to each other in an antiparallel manner to form a ferrimagnet,where the easy magnetization direction at 2 K was the[110]axis in the basal(a,b)plane.This magnetic structure underwent two successive spin reorientation phenomena with increasing temperature.A large Dy magnetic moment of 9.7 Bohr magneton(μB)was obtained at low temperatures,and the magnitude decreased rapidly to 7.5μB at 200 K.The largest Fe magnetic moment was observed on the Fe 8i position.A ThMn12-type crystal structure was preserved in the studied temperature range,despite the large changes of the magnetic structure.A sharp tilt was observed at the first-order spin reorientation,TSR1;the angle between the easy magnetization axis and the crystal c axis was reduced from 90°at 2 K to about 20°at 200 K(where c is the easy axis above 200 K);and the Dy and Fe magnetic moments maintained an antiparallel coupling.展开更多
The crystallographic structure and magnetic properties of La（Fell.4Alz.6）C0.02 are studied by magnetic measurernent and powder neutron diffraction with temperature and applied magnetic field. Rietveld refinement sho...The crystallographic structure and magnetic properties of La（Fell.4Alz.6）C0.02 are studied by magnetic measurernent and powder neutron diffraction with temperature and applied magnetic field. Rietveld refinement shows that La（Fe11.4Al1.6）C0.02 crystallizes into the cubic NaZn13-type with two different Fe sites： FeI （8b） and FeII （96i）, and that A1 atoms preferentially occupy the FeII site. A ferromagnetic state can he induced at a medial temperature of 39 K-139 K by an external magnetic field of 0.7 T, and a large lattice is correspondingly found at 100 K and 0.7 T. In all other conditions, La（Fe11.4Al1.6）C0.02 has no net magnetization in the paramagnetic （T 〉 TN = 182 K） or antifer- romagnetic states, and thus keeps its small lattice. Analysis of the Fe Fe bond length indicates that the ferromagnetic state prefers longer Fe-Fe distances.展开更多
The crystallographic and magnetic structures of Er2Fe15Al2 and Er2Fe12Al5 have been refined in Gaussian peak-shape by Rietveld analysis of Neutron diffrac- tion data. The refined results indicated that Er2Fe15Al2 comp...The crystallographic and magnetic structures of Er2Fe15Al2 and Er2Fe12Al5 have been refined in Gaussian peak-shape by Rietveld analysis of Neutron diffrac- tion data. The refined results indicated that Er2Fe15Al2 compound has Th2Ni17-type hexagonal structure （space group: P63/mmc） and Er2Fe12Al5 has Th2Zn17-type rhom- bohedral structure （space group:R 3m）. The Al atoms prefer 12j and 12k sites with occupancies 0.21 and 0.13, respectively, in Er2Fe15Al2 and prefer 18f, 18h and 6c sites with occupancies 0.35, 0.36 and 0.37, respectively, in Er2Fe12Al5. The magnetic mo- ments of all Fe atoms display ferromagnetically arrangement and the moments of Er atoms couple ferrimagnetically to the moments of the Fe atoms. The moments lie in the plane perpendicular to the six-fold axis and exhibit planar magnetic anisotropy in both samples. The values of To were given and the neutron refined results coincide with that of the magnetic measurements. The relation between magnetic properties and structures was discussed.展开更多
Neutron diffraction technology as an advanced material research technique has special advantages in studying magnetic materials compared to the conventional techniques such as X-ray diffraction(XRD),scanning electron ...Neutron diffraction technology as an advanced material research technique has special advantages in studying magnetic materials compared to the conventional techniques such as X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).In this review,the applications of neutron diffraction technology on permanent magnetic materials were briefly reviewed:(1)the determination of the crystal structure and magnetic structure of the typical permanent magnet material,(2)in situ neutron diffraction study of the crystal structure evolution of the permanent magnets,and(3)phase transition in permanent magnetic materials.展开更多
利用Rietveld分析方法对钙钛矿锰氧化物La1-xCaxMn0.96Fe0.04O3(x=0.31、0.5、0.6)室温下中子衍射实验数据进行拟合。结果表明,La1-xCaxMn0.96Fe0.04O3化合物具有MnO6八面体,空间群为Pnma,La(Ca)原子占据4c晶位,Mn(Fe)原子占据4b晶位,O...利用Rietveld分析方法对钙钛矿锰氧化物La1-xCaxMn0.96Fe0.04O3(x=0.31、0.5、0.6)室温下中子衍射实验数据进行拟合。结果表明,La1-xCaxMn0.96Fe0.04O3化合物具有MnO6八面体,空间群为Pnma,La(Ca)原子占据4c晶位,Mn(Fe)原子占据4b晶位,O原子分别占据4c和8d晶位。根据拟合结果,计算出Mn O键的键长和Mn O Mn的键角,并对该系列样品结构和磁性能间的关系进行了简单讨论。展开更多
In this paper, the structure and magnetic properties of FeRh alloy thin films with a small amount of Pt doping fabricated onto a glass substrate by sputtering are investigated systematically. XRD results show that the...In this paper, the structure and magnetic properties of FeRh alloy thin films with a small amount of Pt doping fabricated onto a glass substrate by sputtering are investigated systematically. XRD results show that the diffraction pattern of as-deposited film exhibits only nonmagnetic y phase. After annealing, the disordered γphase transforms to an ordered α＇ phase. The temperature dependence of saturation magnetization of different annealing times and Pt contents are characterized. The phase transition temperature increases as the Pt component is increased, but the saturation magnetization reduces as the Pt component is in- creased. These results may be caused by the growth of the disordered γ phase.展开更多
文摘In this article,we report on the magnetic structure of DyFe11Ti and its thermal evolution as probed by neutron powder diffraction.A thermodiffraction technique was used to follow the temperature dependence of the magnetic moments,as well as their orientation.The Dy and Fe moments were coupled to each other in an antiparallel manner to form a ferrimagnet,where the easy magnetization direction at 2 K was the[110]axis in the basal(a,b)plane.This magnetic structure underwent two successive spin reorientation phenomena with increasing temperature.A large Dy magnetic moment of 9.7 Bohr magneton(μB)was obtained at low temperatures,and the magnitude decreased rapidly to 7.5μB at 200 K.The largest Fe magnetic moment was observed on the Fe 8i position.A ThMn12-type crystal structure was preserved in the studied temperature range,despite the large changes of the magnetic structure.A sharp tilt was observed at the first-order spin reorientation,TSR1;the angle between the easy magnetization axis and the crystal c axis was reduced from 90°at 2 K to about 20°at 200 K(where c is the easy axis above 200 K);and the Dy and Fe magnetic moments maintained an antiparallel coupling.
基金supported by the National Basic Research Program of China (973 Program) (Grant No. 2010CB833102)the National Natural Science Foundation of China (Grant No. 10974244)
文摘The crystallographic structure and magnetic properties of La（Fell.4Alz.6）C0.02 are studied by magnetic measurernent and powder neutron diffraction with temperature and applied magnetic field. Rietveld refinement shows that La（Fe11.4Al1.6）C0.02 crystallizes into the cubic NaZn13-type with two different Fe sites： FeI （8b） and FeII （96i）, and that A1 atoms preferentially occupy the FeII site. A ferromagnetic state can he induced at a medial temperature of 39 K-139 K by an external magnetic field of 0.7 T, and a large lattice is correspondingly found at 100 K and 0.7 T. In all other conditions, La（Fe11.4Al1.6）C0.02 has no net magnetization in the paramagnetic （T 〉 TN = 182 K） or antifer- romagnetic states, and thus keeps its small lattice. Analysis of the Fe Fe bond length indicates that the ferromagnetic state prefers longer Fe-Fe distances.
基金Nuclear Industry Science Foundation !(H7196B0109) National Nature Science Foun dation of China (19835050)
文摘The crystallographic and magnetic structures of Er2Fe15Al2 and Er2Fe12Al5 have been refined in Gaussian peak-shape by Rietveld analysis of Neutron diffrac- tion data. The refined results indicated that Er2Fe15Al2 compound has Th2Ni17-type hexagonal structure （space group: P63/mmc） and Er2Fe12Al5 has Th2Zn17-type rhom- bohedral structure （space group:R 3m）. The Al atoms prefer 12j and 12k sites with occupancies 0.21 and 0.13, respectively, in Er2Fe15Al2 and prefer 18f, 18h and 6c sites with occupancies 0.35, 0.36 and 0.37, respectively, in Er2Fe12Al5. The magnetic mo- ments of all Fe atoms display ferromagnetically arrangement and the moments of Er atoms couple ferrimagnetically to the moments of the Fe atoms. The moments lie in the plane perpendicular to the six-fold axis and exhibit planar magnetic anisotropy in both samples. The values of To were given and the neutron refined results coincide with that of the magnetic measurements. The relation between magnetic properties and structures was discussed.
基金financially supported by the National Key Research and Development Program of China(Nos.2017YFA0403701,2016YFB0700901,2017YFA0206303 and 2017YFA0401502)the National Natural Science Foundation of China(Nos.51731001,11675006,11805006,51371009 and 11504348).
文摘Neutron diffraction technology as an advanced material research technique has special advantages in studying magnetic materials compared to the conventional techniques such as X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).In this review,the applications of neutron diffraction technology on permanent magnetic materials were briefly reviewed:(1)the determination of the crystal structure and magnetic structure of the typical permanent magnet material,(2)in situ neutron diffraction study of the crystal structure evolution of the permanent magnets,and(3)phase transition in permanent magnetic materials.
文摘利用Rietveld分析方法对钙钛矿锰氧化物La1-xCaxMn0.96Fe0.04O3(x=0.31、0.5、0.6)室温下中子衍射实验数据进行拟合。结果表明,La1-xCaxMn0.96Fe0.04O3化合物具有MnO6八面体,空间群为Pnma,La(Ca)原子占据4c晶位,Mn(Fe)原子占据4b晶位,O原子分别占据4c和8d晶位。根据拟合结果,计算出Mn O键的键长和Mn O Mn的键角,并对该系列样品结构和磁性能间的关系进行了简单讨论。
基金supported by the National Natural Science Foundation of China (Grant No. 50901052)the Program for Young Excellent Talents in Tongji University (Grant No. 2009KJ003)the "Chen Guang" Project(Grant No. 10CG21) of the Shanghai Municipal Education Commission and Shanghai Education Development Foundation
文摘In this paper, the structure and magnetic properties of FeRh alloy thin films with a small amount of Pt doping fabricated onto a glass substrate by sputtering are investigated systematically. XRD results show that the diffraction pattern of as-deposited film exhibits only nonmagnetic y phase. After annealing, the disordered γphase transforms to an ordered α＇ phase. The temperature dependence of saturation magnetization of different annealing times and Pt contents are characterized. The phase transition temperature increases as the Pt component is increased, but the saturation magnetization reduces as the Pt component is in- creased. These results may be caused by the growth of the disordered γ phase.
