Ce1+εFe4B4合金一维无公度调制结构的透射电子显微镜研究

用电子衍射和高分辨电子显微术研究了永磁合金Ce₁₅Fe(77)B₀中富硼相Ce_1+εFe₄B₄(ε≈0.1)的晶体结构,确定了Ce_1+εFe₄B₄合金具有烟囱-梯子型一维无公度调制结构,它由Ce原子和Fe-B原子团分别组成的两套亚结构相互嵌套形成。Ce亚结构晶胞参数为a=7.08?,c_Ce=3.51—3.60?关键词：

ELECTRON DIFFRACTION AND HIGH RESOLUTION MICRO-SCOPY STUDY ON INCOMMENSURATE MODULATED STRUCTURE IN Ce1+εFe4B4 ALLOY

The permanent magnetic alloy Ce_1+εFe₄B₄(ε= 0.1, B-rich phase) is studied by means of electron diffraction and high resolution electron microscopy. It has been determined that the Ce_1+εFe₄B₄ alloy has a one-dimensional incommensurate modulated structure of Chimney-Ladder type consisting of two overlapped substructures fomed by Ce atoms and Fe-B clusters respectively. The unit cell parameters of Ce substructure are a = 7.08?, c_Ce= 3.51-3.60?, and the possible space groups are I4,I4,I4mm, I4/m, I4/mmm. The unit cell parameters of Fe-B substructure are a = 7.08?, c_Fe= 3.91?, and the space group is P/4₂/mcm. All of the major and satellite diffraction spots are indexed by using of four indexes method. The high resolution electron microscopic image shows contrast modulation bands corresponding to the modulated structure. The fluctuation of the period of Ce substructure has been observed and discussed. The orientational anormaly caused by the possible deviation of Ce atomic planes from the (a, b) plane is also discused.
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