电子衍射花样标定.pdf

4.4 电子衍射谱标定 Indexing: the zone axis [uvw] (plane normal) and at least one low index spot (hkl) (normally two spots), with hu+kv+lw=0. 4.4 电子衍射谱标定 图3.9 Al Ni 型正交相Al Fe Ni 的选区电子衍射花样 3 74.8 1.5 23.7 Indexing of 2D patterns 3D reciprocal lattice 3D real lattice orientation/phase identification 4.4.1 The size of diffraction patterns (1/λ)/ghkl ＝L/Rhkl ’ R’d = λL When is θsmall (electron (hkl) diffraction), Rd=λL=diffraction constant S/λ= k θ S /λ= k 0 0 L= 相机 长度 ghkl (hkl) 000 ’ R hkl R hkl (hkl) known substance S/λ= k A table of interplanar spacings d is needed. S /λ= k 相机长度 0 0 ghkl a) Choose three spots such as h k l , h k l , h k l . 3 3 3 1 1 1 2 2 2 000 b) Measure the d values, and thus determine the indices. c) By trial and error a consistent R