L(?) Manqi State Key Laboratory of Rapidly Solidified and Non-Equilibrium Alloys
,
International Centre for Meterials Physics
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
ChinaWAGENDRISTEL A Iastitut fur Anwend Physik
,
Technische Universitat in Wien
,
Austria associate professor
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang 110015
,
China
金属学报(英文版)
The room temperature stability and crystallization of amorphous Nd_xFe_(1-x)thin films with x=0.06—0.90,prepared by flash evaporation at 77 K,were investigated by X-ray diffraction and TEM observation.The amorphous Nd_xFe_(1-x)films are stable at room temperature when 0.19
关键词:
amorphous film
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null
,
null
Physica Status Solidi B-Basic Research
The perturbation formulae of EPR g-factors g(i) (i = x, y, z) and hyperfine constants Ai for a 3d(7) (Co2+) ion at a rhombic octahedral site in a crystal are established from a cluster approach. In these formulae, the contributions from the covalency effect, the configuration interaction and the rhombic crystal field are considered and the parameters used in the calculation of EPR parameters. except the core polarization constant x in the calculation of Al, can be estimated from the optical spectra and the structure data of the studied system. From these formulae, the EPR parameters g(i) and A(i) for the rhombic Co2+-V-Ag centre in AgCl are reasonably explained by considering suitable rhombic distortion and so the microstructure of this rhombic centre is obtained.
关键词:
superposition model;crystals
Physica Status Solidi B-Basic Research
The EPR g-factors g(\\), g(perpendicular to) and hyperfine structure constants A(\\), A(perpendicular to) for a tetragonal Co2+ centre, i.e.. Co(H2O)(2)Cl-4 centre, in NH4Cl crystal are calculated from the perturbation formulas based on a cluster approach. In these formulas, the parameters related to the contributions from the configuration interaction. the covalency effect and the low-symmetry crystal field can be obtained from the optical spectra and the structural model and data of the studied system. The core polarization constant it in the calculation formulas of hyperfine constants is used as an adjustable parameter. The calculated results are in good agreement with the observed values.
关键词:
superposition model;centers;resonance;ions;cr3+
Pramana-Journal of Physics
By calculating the optical spectrum band positions and EPR parameters (g factors, g(parallel to), g(perpendicular to) and zero-field splitting D) by diagonalizing the complete energy matrix of 3d(8) ions in trigonal symmetry, the defect structure of Ni2+ centre in alpha-LiIO3 crystal is studied. It is found that to reach the good fits of optical and EPR data between calculation and experiment, the Ni2+ ion should shift by Delta z approximate to 0.298 angstrom along C-3-axis and the O-2-ions between the Ni2+ ion and Li+ vacancy (V-Li) should be displaced away from the V-Li by Delta x approximate to 0.097 angstrom because of the electrostatic interaction. The results are discussed.
关键词:
Optical spectra;electron paramagnetic resonance;defect structure;Ni2+;alpha-LiIO3.;field;ions;cr3+;temperature;parameters;epr;pressure;model;liio3
Douxing LI and Hengqiang YE (Laboratory of Atomic imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang
,
110015
,
China)
材料科学技术（英文）
The present paper summarizes the current status of high resolution electron microscopy (HREM)and the applications of HREM to materials science and condensed matter physics. This review recounts the latest development of high resolution electron microscope, progress of HREM and the applications of HREM, including the crystal structure determination of microcrystalline materials and characterization of the local structure of the defects and nanostructured materials as well as qualitative and quantitative analysis of the grain boundaries, interfaces and interfacial reactions in the advanced materials by means of HREM in combination with electron diffraction,subnanometer level analysis, image simulation and image processing.
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