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A structural, magnetostrictive and Mssbauer study of Tb0.3Dy0.7(Fe0.9T0.1)1.95 alloys

Science china(Physics,Mechanics & Astronomy) 2005年第6期Mechanics & Astronomy) .卷 750-756页

作者： ZHENG Xiaoping1,2, ZHANG Peifeng1,3, FAN Duowang1, LI Fashen3 & HAO Yuan4 1. key laboratory of Opto-Electronic Technology and Intelligent Control, education ministry of china, lanzhou Jiaotong university, lanzhou 730070, china 2. lanzhou Teachers College, lanzhou 730070, china 3. key laboratory for magnetism and magnetic materials, education ministry of china, lanzhou university, lanzhou 730000, china 4. State key laboratory of New Nonferrous Metal materials, lanzhou university of Technology, lanzhou 730050, china

The effect of Ⅲ A metal and transition metal T substitution for Fe on crystal structure, magnetostriction and spontaneous magnetostriction, anisotropy and spin reorientation of a series of polycrystalline Tb0.3Dy0.7(Fe0.9T0.1)1.95 (T = Mn, Fe, Co, B, Al, Ga) alloys at room temperature were investigated systematically. It was found that the primary phase of the Tb0.3Dy0.7(Fe0.9T0.1)1.95 alloys is the MgCu2-type cubic Laves phase structure for different substitution. The magnetostriction λs decrases greatly for the substitution of IIIA metal B, Al and Ga, but is saturated more easily for Al and Ga substitution, showing that the Al and Ga substitution is beneficial to a decrease in the magnetocrystalline anisotropy of Tb0.3Dy0.7(Fe0.9T0.1)1.95 alloys. However, the substitution of transition metal Mn and Co decreases slightly the magnetostriction λs. It was also found that the effect of different substitutions on the spontaneous magnetostriction λ111 is distinct. The analysis of the M?ssbauer spectra indicates that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry for Al and Ga substitution, namely spin reorientation, but it does not change evidently for B, Mn and Co substitution.

关键词： magnetostriction cubic Laves phase spin reorientation M?ssbauer.

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magnetic,magetostrictive properties,spin reorientation and Mssbauer effect of Tb_(0.3)Dy_(0.7-x)Prx(Fe_(0.9)Al_(0.1))_(1.95) alloys

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Science china(Physics,Mechanics & Astronomy) 2009年第1期52卷 52-57页

作者： ZHENG XiaoPing1,2, ZHANG PeiFeng2,3, FAN DuoWang3 & LI FaShen3 1 Institute of Electronic Information Science and Technology, lanzhou City university, lanzhou 730070, china 2 key laboratory of Opto-Electronic Technology and Intelligent Control, ministry of education, lanzhou Jiaotong university, lanzhou 730070, china 3 key laboratory for magnetism and magnetic materials, ministry of education, lanzhou university, lanzhou 730000, china 1. Institute of Electronic Information Science and Technology Lanzhou City University Lanzhou 730070 China 2. key laboratory of Opto-Electronic Technology and Intelligent Control Ministry of Education Lanzhou Jiaotong University Lanzhou 730070 China 3. key laboratory for magnetism and magnetic materials Ministry of Education Lanzhou University Lanzhou 730000 China

The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties, anisotropy, spin reorientation and Mssbauer effect of a series of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 (x=0,0.1,0.20,0.25,0.30,0.35) alloys at room temperature have been investigated. It was found that a small amount of Pr substitution is beneficial to a decrease in the magnetocrystalline anisotropy for the Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 alloys. The magnetostriction decreases drastically with increasing x and the magnetostrictive effect disappears for x>0.2. However, the magnetostriction exhibits a slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H. The saturation magnetization and Curie temperature decrease monotonously, but the spontaneous magnetostriction increases linearly with increasing x, whereas the spin reorientation temperature increases first, then decreases rapidly and reaches the maximum at x=0.1. The analysis of Mssbauer spectra indicated that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the Pr concentration x, namely spin reorientation. Compared with Al substitution for Fe, the effect of Pr substitution for Dy on spin reorientation is relatively small. The hyperfine field increases with Pr concentration increasing, and the isomer shifts and the quadrupole splitting (QS) show weak concentration dependence.

关键词： magnetostriction anisotropy spin reorientation Mssbauer

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magnetic properties and tunneling magnetoresistance in FeCo-SiO_2 granular films

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Chinese Science Bulletin 2001年第9期46卷 734-737页

作者： XI Li, ZHANG Zongzhi, CHI Junhong, LI Chengxian & GE Shihuikey laboratory for magnetism and magnetic materials of the ministry of education, lanzhou university, lanzhou 730000, china key laboratory for magnetism and magnetic materials of the ministry of education Lanzhou University Lanzhou China

Fefv(SiO2)1-fv granular films were fabricated by rf sputtering (fv represents the Fe volume fraction). The mi-crostructure, magnetic properties as well as the tunneling magnetoresistance effect (TMR) were systematically studied. It was found that the maximum TMR ratio is about -3.3% at fv = 0.33. Under the same condition, a series of (Fe100-x Cox)0.33(SiO2)0.67 were prepared. TMR value reaches -4.5% at x=53, while the microstructure of the film still keeps as that of Fe0.33(SiO2)0.67. The higher TMR ratio is contributed to the elevating of the spin polarization of particles. This is consistent with Inoue’s theory.

关键词： tunneling magnetoresistance granular films.

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Numerical study on short-circuit current of single layer organic solar cells with Schottkey contacts

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Science china(Technological Sciences) 2010年第4期53卷 1023-1027页

作者： MA ChaoZhu1,MENG WeiMin2,PENG YingQuan1,2,WANG RunSheng1,LI RongHua1,XIE HongWei1,WANG Ying1 & YE ZaoChen1 1 Institute of Microelectronics of School of Physical Science and Technology,lanzhou university,lanzhou 730000,china 2 key laboratory for magnetism and magnetic materials of the ministry of education,lanzhou university,lanzhou 730000,china Institute of Microelectronics of School of Physical Science and Technology Lanzhou University Lanzhou China key laboratory for magnetism and magnetic materials of the ministry of education Lanzhou University Lanzhou China

The influence of the cathode work function,carriers mobilities and temperature on the short-circuit current of single layer organic solar cells with Schottkey contacts was numerically studied,and the quantitative dependences of the short-circuit current on these quantities were *** results provide the theoretical foundation for experimental study of single layer organic solar cells with Schottkey contacts.

关键词： cathode work function carrier mobility temperature short-circuit current

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MULTISCALE MECHANICAL BEHAVIORS IN DISCRETE materials: A REVIEW

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Acta Mechanica Solida Sinica 2010年第6期23卷 579-591页

作者： Xiaojing Zheng Dengming Wang (key laboratory of Mechanics on Western Disaster and Environment,the ministry of education of china,lanzhou university,lanzhou 730000,china) key laboratory of Mechanics on Western Disaster and Environment the Ministry of Education of China Lanzhou University Lanzhou China

The discrete material, which belongs to the category of soft materials, is one of the most prevalent forms of matter in nature and engineering fields. These materials often exhibit abundant and complex mechanical properties which are still far from being perfectly understood. From the view of multi-scale framework concentrated on the ＇bridge＇ role in the macro-micro relation, this review mainly introduces some theoretical investigations of mechanical behaviors in discrete materials, including the continuum constitutive model based on the macroscopic phenomenological approach and coupled micro-macro approach, the statistical analysis of some microscopic physical quantities involved contacted forces between particles and its transmission within the whole system, and the statistical analysis for some microscopic processes in aeolian landform systems involving the grain-bed impact, the transportation and sedimentation of wind-blown sand flux, et al. Finally, some further worthwhile challenges in these fields are suggested.

关键词： discrete material multiple space and time scales trans-scales correlation sanddune statistical analysis

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Dating and genesis of the upper Weihe River terraces in Longxi basin,china

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Progress in Natural Science:materials International 2007年第11期17卷 1334-1340页

作者： Pan Baotian, Liu Xiaofeng, Gao Hongshan, Wang Yong and Li Jijun(key laboratory of Western china’s Environmental System, ministry of education, lanzhou university, lanzhou 730000, china) key laboratory of Western china's Environmental System Lanzhou University Lanzhou 730000 China

Seven terraces along the Weihe River in Longxi basin have been investigated. These terraces all consist of archetypal duality in structure, namely the floodplain deposits and the layer of gravels overlaid by varying thickness of the loess. By resorting to various dating approaches such as palaeomagnetic, optically stimulated luminescenece (OSL), 14C and loess-paleosol sequence, we provide preliminary timing of these seven terraces along upper Weihe River. Analysis on sedimentation characteristics and dating of these terraces showed that seven terraces may be jointly generated by tectonic uplifts and climatic changes. Tectonic uplifts may accommodate initial river incision, and climatic change may be responsible for processes of subsequent channel widening and aggradation. Aggradation normally occurs during glacial periods, in contrast to down-cuttings during transitions from glacial to interglacial period. Moreover, on the basis of the timings and heights of these terraces, we infer that the long-term rate of river incision was determined to be 0.2 m/kyr during the last 870 kyr, which differs from other river incision rates. This discrepancy may reflect spatio-temporal differentiation of tectonic activities in the Qinling orogenic belt during the Pleistocene.

关键词： loess stratigraphy river terraces climate change Upper Weihe River

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Soft magnetic properties of (Ni_(50)Fe_(50)) SiO_2 granular thin films for high frequency application

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Rare Metals 2006年第Z1期25卷 650-654页

作者： YANG Xiaolin GE Shihui RUAN Chengli College of Physics and Electronic Science University of Electronic Science and Technology of China Chengdu 610054 China Key Laboratory for Magnetism and Magnetic Materials of Ministry of EducationLanzhou University Lanzhou 730000 China College of Physics and Electronic Science University of Electronic Science and Technology of China Chengdu 610054 China

A series of (Ni50Fe50)x(SiO2)(1-x) films with different volume fraction x was fabricated by magnetron co-sputtering technique. The microstructure, magnetic and electrical properties were investigated systematically by using X-ray diffraction, transmission electronic microscope, vibrating sample magnetometer and the traditional four point measurement method of resistivity. The results show that the samples consist of nano-scaled Ni50Fe50 metallic particles with fcc structure uniformly embedded in amorphous insulating SiO2 matrix, and the particle size decreases with the decrease of x. The rapid change of coercivity with x is observed, and a minimum value 160 A·m-1 of Hc was obtained for the sample of x=0.83 with film thickness of 180 nm, which can be contributed to the exchange coupling between nano-scaled Ni50Fe50 particles. At the frequency lower than 1 GHz, the real part μ′ of complex permeability keeps about 110 and the image part μ″ is less than 15. Besides, this film exhibits high resistivity ρ=263 μΩ·cm, high saturation magnetization 4πMs=1.25 T, high in-plane magnetic anisotropy field Hk=6.37 kA·m-1, and the ferromagnetic resonance (FMR) frequency is estimated to be 2.8 GHz. Therefore, this film can be used in high frequency devices operating over 2 GHz.

关键词： thin films nanostructure magnetic properties

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Discovery of a 1.0 Ma Yellow River terrace and redating of the fourth Yellow River terrace in lanzhou area

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Progress in Natural Science:materials International 2007年第2期17卷 197-205页

作者： PAN Baotian , SU Huai, HU Chunsheng, HU Xiaofei, ZHOU Tian and LI Jijun (key laboratory of Western china’s Environmental Systems, ministry of education, and Department of Geography, lanzhou university, lanzhou 730000, china) key laboratory of Western china's Environmental System MOE Department of Geography Lanzhou University Lanzhou 730000 China

Based on the aeolian loess sequence-stratigraphic division and paleomagnetic datings on terraces, we found that an undiscovered terrace with the age of 1.0 Ma BP lies between the Dunwashan terrace and Wuyishan terrace. This terrace recorded an intensive Yellow River incision event during that period. Results of paleomagnetic dating and optically stimulated luminescence (OSL) dating of the Wuyishan loess section and Zaoshugou loess section on the fourth Yellow River terrace (T4) show that the age of the fourth Yellow River terrace in lanzhou area is 0.86 Ma BP rather than the previously believed 0. 6 Ma BP. This result answers a long-term question in the ge-omorphology community of whether there exists a 0. 8 Ma terrace in lanzhou area. The discovery of the 1. 0 Ma Yellow River terrace and redating of the age of 0.6 Ma terrace in lanzhou area provide new insights into further research on the evolution of Yellow River.

关键词： lanzhou area Yellow River terrace dating.

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Terrace dating as an archive of the run-through of the Sanmen Gorges

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Progress in Natural Science:materials International 2005年第12期15卷 1096-1103页

作者： PAN Baotian,WANG Junping,GAO Hongshan,CHEN Yingying,LI Jijun and LIU Xiaofeng key laboratory of Western china’s Environmental Systems,ministry of education,and Department of Geography,lanzhou university,lanzhou 730000,china key laboratory of Western china's Environmental Systems of ministry of education Department of Geography Lanzhou University Lanzhou 730000 China

Analysis of morphological properties in the Sanmen Gorges region of the Yellow River shows that four river terraces have been developed at the entrance to the ***,thick aeolian loess-paleosol sequence was deposited on the terraces,which makes it easy to date the *** dating of paleomagnetic,loess-paleosol sequence matching and thermoluminescence show that terraces T2,T3 and T4 were formed 0.129 Ma,0.625 Ma and 0.865 Ma ago,*** formation of these terraces in this region indicates that the Yellow River has experienced four intensive downcutting events during the last 0.9 *** Yellow River cut through the Sanmen Gorges and inpoured into the East china Sea no later than 0.865 Ma.

关键词： river terrace paleomagnetic dating Yellow River loess

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Comparison of sensible and latent heat fluxes during the transition season over the western Tibetan Plateau from reanalysis datasets

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Progress in Natural Science:materials International 2009年第6期19卷 719-726页

作者： Yang Cui, Chenghai Wang Disaster Reduction key laboratory of Gansu Province, College of Atmospheric Sciences, lanzhou university, lanzhou 730000, china Disaster Reduction key laboratory of Gansu Province College of Atmospheric Sciences Lanzhou University Lanzhou 730000 China

The sensible and latent heat fluxes during the transition season over the western Tibetan Plateau from the NCEP-1 (NCEP/NCAR Reanalysis 1), AR-Ⅱ (NCEP-DOE Reanalysis 2) and ERA40 reanalysis datasets were compared and analyzed. The results show that the phase change in soil moisture has a significant effect on the sensible and latent heat fluxes over the western Tibetan Plateau (TP) due to the freezing-thawing processes during the transition from the dry to the wet period. The uncertainties in the sensible and latent heat fluxes over the western TP are quite high in the reanalysis data, and depend largely on the success of the soil moisture simulations in the models. Improving the hydrological process simulations in the land-surface models in seasonally frozen ground and in the active frozen soil layer may be an effective way of enhancing the reliability of the surface heat fluxes from the reanalysis data over the Tibetan Plateau.

关键词： Western Tibetan Plateau Surface heat fluxes Reanalysis data Transition season Freezing-thawing process

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