共查询到20条相似文献,搜索用时 296 毫秒
1.
Energies for the ground states of double-electron systems in a uniform magnetic fieldB≤109 G are calculated by using the modified Slater basis and configuration interaction method, and the result for energy in zero
magnetic field is comparable with those obtained by different methods.
Supported by the Opening Foundation of Wuhan Institute of Physics, Chinese Academy of Science
Wu Liangkai: born in 1970, Graduate student 相似文献
2.
WEI Fengsi FENG Xueshang YANG Fang & ZHONG Dingkun SIGMA Weather Group Laboratory for Space Weather Center for Space Science Applied Research Chinese Academy of Sciences Beijing China Correspondence should be addressed to Feng Xueshang 《科学通报(英文版)》2004,49(23):2533-2537
Magnetic cloud is an important interplanetary dis-turbance structure generated by the coronal mass ejections(CMEs), it has been widely investigated[1—5] since it wassuggested by Burlaga et al[1]. However, the boundary ofthe magnetic cloud has no objective definition yet. Manyobservational signatures have been used to identify thecloud boundary[6—13], as Burlaga[14] indicated, there is noconsistency among these various approaches. The problemof the BLs was not been solved because of its co… 相似文献
3.
GUO Yuxian WANG Jie LI Honghong XU Pengshou CAI Jianwang 《科学通报(英文版)》2006,51(16):1934-1938
With the development of information technology, the data storage capacity of magnetic recording media has been increasing rapidly in recent years. To achieve areal densities as high as one terabit per square inch (Tb·in?2), roughly 20 times of today’s p… 相似文献
4.
食品安全是全社会高度关注的话题,低场核磁共振(LF-NMR)技术因无需前增菌,具有灵敏度高、操作简便、设备与试剂国产化率高等特点,在食品安全检测中引起了广泛关注.弛豫时间的变化是LF-NMR的关键性检测指标.从横向弛豫时间T_2、纵向弛豫时间T_1的形成原理和特点出发,综述了基于T_2转换原理的生物传感器在食品掺假、食品保鲜、化学污染物、微生物等领域的检测应用,以及T_1在提高定量分析的灵敏度方面的作用. 相似文献
5.
V2O5/TiO2 composite films were prepared on pure titanium substrates via micro-arc oxidation (MAO) in electrolytes consisting of NaVO3. Their morphology and elements were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis. Phase composition and valence states of species in the films were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS) were also employed to evaluate the photophysical property of the films. The V2O5/TiO2 composite films show a sheet-like morphology. Not only V2O5 phase appears in the films when the NaVO3 concentration of the electrolyte is higher than 6.10 g/L and is loaded at the surface of anatase, but also V4+ is incorporated into the crystal lattice of anatase. In comparison with pure TiO2 films the V2O5/TiO2 composite films exhibit significantly narrow band gap energy. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the narrowest band gap energy, which is approximately 1.89 eV. The V2O5/TiO2 composite films also have the significantly enhanced visible light photocatalytic activity. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the best photocatalytic activity and about 93% of rhodamine is degraded after 14 h visible light radiation. 相似文献
6.
PENG YingZi THOMAS Liew YE ZhiZhen ZHANG YinZhu 《科学通报(英文版)》2007,52(20):2742-2746
The crystallographic structures and magnetic properties of a Zn0.95Co0.05O thin film deposited on a C-sapphire substrate using a dual-beam pulsed laser deposition method were characterized. It was shown from crystallographic analysis that the film belongs to the wurtzite structure with the C-axis aligned with that of the substrate. Magnetic hysteresis loops were observed till up to room temperature. A small peak around 55 K was noticed on the magnetization vs. temperature curve. The corresponding temperature of the small peak is close to that of ‘the abnormal peak’ reported by X.M. Zhang et al. From the results obtained, no correlation was found between the abnormal peak and the quantum effects. The magnetic behaviors in the Zn0.95Co0.05O film cannot be explained by the ferromagnetism in diluted magnetic semiconductors. The magnetic mechanisms in ZnO-based diluted magnetic semiconductors are also discussed. 相似文献
7.
Graded bandgap semiconductor thin film photoelectrodes 总被引:1,自引:0,他引:1
A graded bandgap oxide semiconductor thin film electrode was designed in order to obtain a photoelec-trochemically stable
photoelectrode, with wide absorption range. The graded bandgap Ti1−x
V
x
O2 film electrode was prepared by heating the stacked layers of V/Ti in varying ratios, which were coated on the substrate by
the sol-gel method using the starting solution with various V/Ti ratios. XPS result showed that the composition gradient was
achieved for the film. The Ti1−x
V
x
O2 film electrode was found to be photoelectrochemically stable. Its photovoltage was about 360 mV. Obvious visible light photoresponse
was observed for the Ti1−x
V
x
O2 film electrode. Compared with the pure TiO2 electrode, the photocurrent onset potential of the Ti1−x
V
x
O2 film electrode was shifted positively, probably because the accumulation of vanadium at the electrode surface causes the
recombination of the electrons and holes, and the lowest level of the conduction band of Ti1−x
V
x
O2 is lower than that of TiO2. Impedance analysis showed that the donor density of the Ti1−x
V2O2 film electrode was higher than that of TiO2 film electrode. 相似文献
8.
对非相互作用磁性纳米颗粒系统的FMR线型模型进行了研究,以铁磁体从应用场中获得自由能F为例,导出磁性颗粒在较小各向异性时,共振场Hr与有效各向异性场HAeff的关系,这个结果与Raikher和Stepanou的结果一致.继而还对共振场线宽进行了分析,并与Smit和Beljers模型进行了比较,其结论说明:在超顺磁区域有效各向异性场HAeff对塞曼(Zeeman)相互作用和附加应用场H是不确定的.尤其是这种情况在HAeff较小、高温(高温区域),且HAeff≈H时,变得更显著.为此提出了随机颗粒阵列及参数特征对这个结果的影响机制. 相似文献
9.
Using (Ti(OC4H9)4) and metal chlorates as starting materials, CoFe2O4/TiO2 composite films were prepared by sol-gel method. The effects of heat treatment temperature and pH of the precursor on microstructure and magnetic properties were studied. The phase structure of the samples was examined by X-ray diffraction. The microstructure was examined by scanning electron microscope, atomic force microscope and polarized microscope. The magnetic property was measured by vibrating sample magnetometer. The results show that the crystals of different phases grow up independently. CoFe2O4 is uniformly embedded into the TiO2 matrix in the prepared composite films, and the growth of composite films is dependent on the heat treatment temperatures and PH of the precursor. The average size of CoFe2O4 crystal is 19 nm in Nanocomposite film prepared when the heat treatment temperature is 800℃ and the pH of the precursor is between 2 and 3. The magnetism of the composite films is enhanced as the heat treatment temperature increases. 相似文献
10.
Qiao Haoxue Tan Zhijie Xia Haibo Zhuang Hongzhang Zou Xianwu Jin Zhunzhi 《武汉大学学报:自然科学英文版》1997,2(3):295-298
The electronic charge transference and local magnetic moment of the YCo5 intermetallic compound were calculated using SCF-MO-DVXα method and multiple cluster model. The result shows that about one
4d-electron is transferred from anY atom to Co1(2c), and the calculated local spin magnetic moments of CoI(2c) and CoII(3g) atoms in YCo5 compound are 1.33 and 1.48μ
B
, respectively, which are in very good agreement with experiments.
Supported by the National Natural Science Foundation of China
Qiao Haoxue: born in Apr. 1970, Master 相似文献
11.
ZHAO Lihong TIAN Zhidong TANG Zheng WANG Ziyu ZHU Benpeng WANG Lili XIONG Rui SHI Jing 《武汉大学学报:自然科学英文版》2007,12(6):1039-1042
Polycrystalline samples of a novel spin-liquid compound Tb2Ti2O7 were prepared by a standard solid-state reaction. X-ray diffraction at room temperature confirms that the synthesized compound of Tb2Ti2O7 is single phase with cubic unit cell constant a0 of 1.015 44 nm. Magnetic susceptibility measurements in the temperature range between 100 and 300 K give an effective moment of 9.44 μB and Curie-Weiss temperature of 12.68 K, respectively, indicating the dominance of antiferromagnetic interactions. However, below 50 K, the magnetic behavior of Tb2Ti2O7 deviates from Curie-Weiss law, whose origin remains suspicion. 相似文献
12.
The giant magneto-optical Faraday effect of nanometer ferromagnetic metal-semiconductor matrix Fe-ln2O3 granular films prepared by the radio frequency sputtering are studied. The result shows that the Faraday rotation angle θF value of the granular film samples with Fe volume fraction x = 35% is of the order of 10^5(°)/cm at room temperature. Temperature dependence of the Faraday rotation angle θF of Fe0.35(In2O3)0.65 granular films shows that θF value below 10 K increases rapidly with the decrease of the temperature, and when T= 4.2 K, θF value is 106(°)/cm. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at different temperatures, it has been found that when the temperature decreases to a critical point Tp = 10 K, the transformation of state from ferro-agnetic to spin-glass-like occurs in Fe0.35(In2O3)0.65 granular films. The remarkable increase of the Faraday rotation angle θF value of Fe0.35(In2O3)0.65 granular films below 10 K seems to arise from the sp-d exchange interaction of the granular film samples in the spin-glass-like state. 相似文献
13.
Nanometer ferromagnetic metal-semiconductor matrix Fe−In2O3 granular films are fabricated by the radio frequency sputtering. Magnetic properties and the giant magnetoresistance (GMR)
effect of Fex(In2O3)1−x granular film samples are studied. The result shows that the magnetoresistance (MR) ratio Δρ/ρ
0 value of the granular film samples with Fe volume fraction x=35% is 4.5% at room temperature. The temperature dependence (T=1.5–300 K) of the MR ratio Δρ/ρ
0 value of Fe0.35(In2O3)0.65 granular films shows that Δρ/ρ
0 value below 10 K increases rapidly with the decrease of the temperature, and when T=2 K, Δρ/ρ
0 value is 85%. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at
different temperatures, it has been found that, when the temperature decreases to a critical point T
p=10 K, the change of the structure in Fe0.35)In2O3)0.65 granular films results in the transformation of state from ferromagnetic to spin-glass-like. The remarkable increase of the
MR ratio Δρ/ρ
0 value of Fe0.35(In2O3)0.65 granular films below 10 K seems to arise from the peculiar conducting mechanism of the granular film samples in the spin-glass-like
state. 相似文献
14.
Rui Xiang Shaoxiong Zhou Bangshao Dong Guangqiang Zhang Zongzhen Li Yanguo Wang Chuntao Chang 《自然科学进展(英文版)》2014,24(6):649-654
The effects of Co addition on the microstructure,crystallization processes and soft magnetic properties of(Fe1 xCox)83Si4B8P4Cu1(x?0.35,0.5,0.65)alloys were investigated.The experimental results demonstrated that the addition of Co decreased the thermal stability against crystallization of the amorphous phase,and thus improved the heat treatment temperature of this alloy.Fe Co Si BPCu nanocrystalline alloys with a dispersedα0-Fe Co phase were obtained by appropriately annealing the as-quenched ribbons at 763 K for 10 min.Theα0-Fe Co with grains size ranging from 9 to 28 nm was identified in primary crystallization.The coercivity(Hc)markedly increased with increasing x and exhibited a minimum value at x0.35,while the saturation magnetic flux density(Bs)shows a slight decrease.The(Fe0.65Co0.35)83Si4B8P4Cu1nanocrystalline alloy exhibited a high saturation magnetic flux density Bsof 1.68 T,a low coercivity,Hcof 5.4 A/m and a high effective permeability meof 29,000 at 1 k Hz. 相似文献
15.
The major drawbacks of Nd-Fe-B magnets are relatively low Curie temperature and poor thermal stability. Ribbons with the near stoichiometric 2:14:1 composition of Nd10.8Dy0.75Tb0.75Fe79.7-xCoxZr0.8Nb0.8Cu0.4B6.0 (x=0, 3, 6, 9, 12, 15) were prepared by rapid quenching and subsequent heat treatment. The effect of Co element on the magnetic properties, thermal stability, and microstructure of the ribbons was systematically studied by vibrating sample magnetometer (VSM), thermal magnetic analysis, atomic force microscopy (AFM), and transmission electron microscopy (TEM). It was found that Co substitution was significantly effective in improving the magnetic properties and the thermal stability of nanocrystalline ribbons. Although the intrinsic coercivity decreased from 1308.7 kA/m for x=0 to 817.4 kA/m for x=15, the remanence polarization and maximum energy product increased from 0.839 T and 116.5 kJ/m3 for the Co-free samples to 1.041 T and 155.1 kJ/m3 for the 12at% Co-substituted samples, respectively. About 10 K increase in Curie temperature was observed for the 2:14:1 phase with 1at% Co substitution. The absolute values of temperature coefficients of induction and coercivity were significantly decreased with Co substitution, which may be attractive for high operational temperature applications. The microstructure of nanocrystalline ribbons was slightly refined with Co substitution. 相似文献
16.
采用单辊快淬法制备Fe40Co40Zr7V2B9Ta2非晶合金薄带,并对该合金在不同温度下进行热处理.利用差热分析(DTA)、X射线衍射(XRD)、扫描电镜(SEM)和振动样品磁强计(VSM)测量合金的热性能、微观结构及磁性能.结果表明:Fe40Co40Zr7V2B9Ta2合金的初始晶化产物为α-FeCo相,高温时析出ZrCo3B2,Co23Zr6和ZrB2相;薄带横断面的形貌在快淬态和300℃退火后,合金的自由面呈网状结构,贴辊面呈枝状结构;高于550℃退火,横断面呈颗粒状;550℃退火后合金的矫顽力(Hc)最小,高于550℃退火,Hc随退火温度的升高而增大. 相似文献
17.
To validate the correctness of the Hartman-Perdok Theory (HPT), which indicates that the {111} planes have the lowest surface energy in spinel ferrites, the {111} plane orientated ZnFe2O4 thin films on Si(100), Si(111), and SiO2(500 nm)/Si(111) substrates were obtained through a radio frequency (RF) magnetron sputtering method with a low sputtering power of 80 W. All of the experiments prove that the atom energy determined by sputtering power plays an important role in the orientated growth of the ZnFe2O4 thin films, and it matches well with HPT. The ZnFe2O4 thin films exhibit ferromagnetism with a magnetization of 84.25 kJ/mol at room temperature, which is different from the bulk counterpart (antiferromagnetic as usual). The ZnFe2O4 thin films can be used as high-quality oriented inducing buffer layers for other spinel (Ni, Mn)Zn ferrite thin films and may have high potential in magnetic thin films-based devices. 相似文献
18.
Li Lei Limin Li Xiuting Wang Zhao Zhang Gaoyang Zhao Jiqiang Jia Fuxue Yan Zongfan Duan Lihua Jin Chengshan Li Pingxiang Zhang 《自然科学进展(英文版)》2020,30(2):180-184
YBa2 Cu3 O7-δ/BaZrO3(YBCO/BZO) composite film with enhanced flux-pinning performance was prepared on LaAlO3(LAO) substrate via a fluorine-free sol-gel method in combination with a novel photosensitive sol-gel lithography technique.Owing to the difference of lattice mismatch between the interfaces of YBCO/LAO and YBCO/BZO,high-density stacking faults were successfully introduced into YBCO matrix,which has been confirmed by XRD and HRTEM analy... 相似文献
19.
A preliminary exploration of the mechanism for the occurrence of two types of various magnetic structures in the magnetotail 总被引:1,自引:0,他引:1
As well known, the magnetic cross-tail component By in the magnetotail is in direct proportion to the in-terplanetary magnetic field (IMF) By component. And the polarity of IMF and plasmoid / flux rope By components do indeed agree. This results indicate that the IMF By penetrates plasmoids and the magnetic structures must therefore be three-dimensional. In this note, the dynamical processes of magnetotail in the course of a substorm are studied using a MHD code with two-dimensions and three components on the basis of two types of initial equilibrium solutions of the quiet magnetotail. The numerical results of two cases illustrate various features of time evolution of By component that correspond to two kinds of plasmoid-like structures: one is associated with a flux rope core and the other resembles a “closed loop” plamoid. Therefore, the occurrence of various magnetic structures in the magnetotail might be related to nonsteady driven reconnection with different distributions of the By component. 相似文献
20.
Analysis of electromagnetic pressure on thin plate melt 总被引:1,自引:0,他引:1
An equation used to calculate electromagnetic pressure for confining and shaping a plate-form melt with small or medium thickness is brought forward. The equation gives a precise relationship between electromagnetic pressure factor p and current frequency f, melt thickness a and electromagnetic parameter μγ . The main results can be summarized as follows: ( i ) As the f, a and μγ are large enough, causing the ratio of melt thickness to current skin depth a/ S to be larger than 2.2, p will be a constant ( p = 1) and the electromagnetic pressure can be calculated with Pm = B2/2λ. ( ii ) As the f, a, and μγare not large enough, and the ratio a/ 8 is less than 2.2, p is no longer a constant but changes from 1 to 0 with the decrease of a/δ. In this case, the value of electromagnetic pressure is determined not only by magnetic flux density 8 but also by the current frequency f, melt thickness a and electromagnetic parameter μγ. 相似文献