检索结果-南通市图书馆

NEXT NEAREST NEIGHBOR effect IN mossbauer SPECTRA OF CHROMITE

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1988年第18期33卷 1548-1551页

作者：李哲金明芝赫伟刘密兰 Institute of Geology Academia SinicaBeijing Department of Physice Jilin UniversityChangchua

Chemical bond properties and M(?)ssbauer spectroscopy in (La_(1-x)M_x)_2CuO_4(M=Ba,Sr)

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2002年第4期21卷 299-303页

作者： GAOFaming ZHANGSiyuan 等 CollegeofMaterialsScienceandChemicalEngineering YanshanUniversityQinghuangdao066004China LaboratoryofRareEarthChemistryandPhysics ChangchunInstituteofAppliedChemistryChineseAcad

By using the average band-gap model, the chemical bond properties of(La_(1-x)M_x)_2CuO_4(M=Ba, Sr) were calculated . The calculated covalencies for Cu-O and La-O bondin the compounds are 0.3 and 0.03 respectively. mossbauer isomer shifts of ^(57)Fe doped inLa_2CuO_4 and ^(119)Sn doped in La_2CuO_4 were calculated by using the chemical surrounding factordefined by covalency and electronic polarizability. Four valence state tin and three valence ironsites were identified in ^(57)Fe and ^(119)Sn

关键词： superconductor rare earth oxide chemical bond mossbauer effect

STRUCTURAL TRANSFORMATION INDUCED BY MECHANICALLY DRIVEN ALLOYING AND SUBSEQUENT MAGNETIC PROPERLIESOF THE Fe-Cu SYSTEM

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1998年第2期11卷 128-136页

作者： Y.Z.Yang Y.HLuo Q.S.Li Y.L.Zhu X.M.Ma Y.D.Dong Y.Z.Chuang Guangdong Univ of Technology Guangzhou China

The structural transformation in Fe-Cu powder induced by mechanically driven alloying has been monitored by the lattice constant measurements and mossbauer spectroscopy. For the samples with Cu higher than 75at.% mossbauer the spectra show a broad paramagnetic doublet; for samples with 50 and 60at.%Cu a new broad ferromagnetic sextet; for those with less than 30at.%Cu similar to those of α-Fe. The main peaks of the hyperfine field distribution significantly broaden and shift to a lower position with increasing Cu content due to the complex environments of iron atoms in the solid solutions and the reduction in the nearest neighbor Fe of a cental Fe atom, respectively. The saturation magnetization of Fe-Cu alloys monotonously decreases with Cu content. The complex composition dependence of coercive field for the milled samples is discussed with respect to the solid dissolution, grain size, interfacial state etc.. The increase of lattice constants with the solute content in the two terminal solid solutions has been explained by the volume-size factor theory or magnetovolume effect.

关键词： mechanical alloying mossbauer effect Fe-Cu alloy magnetic measurement

IRRADIATION　effect　OF　0．56　GeV　C^（6＋）　on　Y_（1．6）Ca_（1．4）V_（0．45）Sn_（0．5）Fe_（4．05）O_（12）

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 1994年第3期5卷 143-148页

作者：熊宏齐夏元复侯明东 PhysicsDepartmentofNanjingUniversity Nanjing210008China

Y1.6Ca1.4V 0.45Sn0.5Fe4.05O12 is irradiated by 0.56 GeV carbon ion. The irradiation effect is investigated by mossbauer spectroscopy. The irradiation results in an isotropic distribution of the hyperfine magnetic field. The hyperfine magnetic fields decrease after the irradiation due to the change of supertransferred field. After the irradiation, the chain Fe(a)-oxygen-Fe(d) become longer and it leads to decrease of the supertransferred field.

关键词： Irradiation effect Energetic carbon ion CaVSn:YIG mossbauer effect Hyperfine field

^(199)Sn AND ^(57)Fe mossbauer SPECTROSCOPIC STUDY OF THE MECHANICALLY ALLOYED Fe-Sn ALLOYS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1998年第5期11卷 335-341页

作者： Y.Z.Yang Y.L.Zhu Q.S.Li X.M.Ma Y.D.Dong Y.Z.Chuang Guangdong Univ of Technology Guangzhou China

Nanocrystalline supersaturated solid solutions (Sa in Fe) with Sn content less than 50 at. %,and FeSn2 and Fe1.3Sn intermetallic compounds have been prepared by mechanical alloying of Fe and Sn mixture powders with composition of Fe1-xSnx (x≤0.5).The atomic alloying the formation and microstructure, especially the coordination environments, of the resultant alloys have been studied by X-ray diffraction, 57Fe and 119Sn mossbauer Spectroscopy and diffrrential scanning calorimetry. The Fe and Sn coordination environments and the composition dependence of the hyperfine parameters on the Fe and Sn content have been fully discussed with respect to the solid dissolution alloying, grain refinement, and distortion caused or induced by mechanical alloying.

关键词： mechanical alloying mossbauer effect nanocrystalline Fe-Sn alloy

An Exact Expression for Fractional Absorption in mossbauer Spectroscopy

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2001年第4期6卷 784-786页

作者： Chen Yi-long Lu Ning Peng Li-li Zhao Lei School of Physics and Technology Wuhan University Wuhan 430072 China

The fractional resonance absorption ε(0) in transmission mossbauer spectroscopy is defined as a relative number of the absorbed γ-ray, and regarded as a measure of mossbauer effect. The absorption linewidth Λ a , as it is usually suggested, is nearly equal to the emission linewidth, Λ s , and such an approximation leads to a extremely simplified expression ε(0), depending on neither Λ s nor Λ a . We consider the general case Λ s ≠Λ a , and obtain an exact expression for ε(0) which is given in the present paper. This expression ε(0), as a function oft a, Λ s , Λ a , is figured and discussed.

关键词： mossbauer effect fractional resonance absorption emission and absorption linewidths

Site occupancies of iron in saimaite and chevkinite

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1999年第24期44卷 2274-2276页

作者： SONG Renkui DING Kuishou LI Zhe Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China

Saimaite is a new Zr-Ti silicate mineral. In this note X-ray and electron probe analyses for saimaite were carried out, and the chemical formula of saimaite was calculated. In addition, the mossbauer effects of saimai... 详细信息

关键词： new mineral saimaite mossbauer effect site occupancy

Preparation and Characterization of Fe_2O_3/Al_2O_3 Nano-composites

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2007年第5期14卷 674-676页

作者：刘梅于文学李海波徐仕翀张晓芬 College of Physics Jilin Normal University College of Materials Science and Engineering Jilin University

Al2O3/Fe2O3 nano-composites were prepared by sol-gel route. The effect of Fe2O3 content on the structure, grain size and characterization of the composite were investigated through X-ray diffraction and mossbauer spectrum. The X-ray diffraction results show that Al2O3/Fe2O3 nano-composites with the Fe2O3 content of 40 wt% can be obtained after heat-treated at 900 ℃. The mossbauer effect results show that all samples exhibit clear super-paramagnetic phenomenon. Particles grow and defects reduce with the increasing of Fe2O3 content and some α-Fe2O3 stay magnetic order.

关键词： nano-composites XRD mossbauer effect

MAGNETIC AND mossbauer STUDY OF ANCIENT YAOZHOU TANG TRICOLOR CERAMICS

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1992年第11期37卷 905-909页

作者：刘中夏王斌李国栋凌启芬李德新郭淑娇 Department of Physics Shaanxi Teacher's UniversityXi'an 710062PRC Institute of Physics Academia SinicaBeijing 100080PRC

Ⅰ. INTRODUCTIONThe valuable information about the ancient ceramics can be acquired from studying their structures, compositions and manufacture technology by modern scientific and technical method. It is an important field of the modern scientific and technological archaeology (STA), which is also called experimental archaeology and has a special significance for the "country of ceramics" .

关键词： ancient Chinese Tang Tricolor ceramics magnetism mossbauer effect