Simulation Of Dynamical Electron Diffraction In EBSD And Non-orthogonal Crystal System By Revised Real Space Method

Nowadays Transmission Electron Microscopy(TEM) and Scanning Electron Microscopy(SEM) are two effective methods to study the micro-structure of materials for scientists. In order to correctly explain the high resolution image obtained by TEM and the electron back scattering diffraction(EBSD) pattern obtained by SEM, and maximally obtain the structure information of the samples, it’s very necessary to simulate the dynamical interaction of the electron beam and the sample.The multi-slice method is widely used as one of the dynamic electron diffraction calculation method. It mainly includes the conventional multi-slice(CMS) method and the real space multi-slice(RS) method. To simplify the question, high approximation is taken in the above two methods. The revised real space multi-slice(RRS) method is a new algorithm based on the multi-slice method,.There is no approximation taken in this method. Therefore, it should be more precise theoretically.. This method is only applied in the orthogonal coordinate system and is only used to simulate the dynamical electron diffraction in orthogonal crystal system now. However, in some cases, the formula will be more convenient for dynamical electron diffraction calculation in non orthogonal coordinate system(for example: in the orthogonal crystal with the incident beam along some crystal axises or in the non-orthogonal crystal). So it’s necessary to derivate the RRS formula in non-orthogonal coordinate system, and simulate the dynamic diffraction pattern. In addition, EBSD diffraction patterns are obtained by the SEM. The working voltages of SEM range from 40 kV to 10 kV. In such a low acceleration voltage, accurate diffraction patterns should be obtained by the RRS method. Based on the above considerations, the main research contents are as following:Firstly, a RRS expression is derived in the non-orthogonal coordinate system,which is convenient for dynamical electron simulation in the non-orthogonal crystal system or in the orthogonal crystal system with the incident plane along some crystal axes). The correctness of the formula is also tested. In addition, by further processing the calculation data, a image processing method is explored in order to obtain the diffraction pattern with the diffraction intensity variation and the symmetry of crystal structure.Secondly, Si[111] with six symmetry in incident plane and Na2Ti3O7 inmonoclinic system are taken as examples. The the calcuations by the RRS in the non-orthogonal crystal system are compared by those by the CMS at the voltage range from 10 kV to 40 kV. The results show that the RRS is more suitable for dynamical simulation in the non-orthogonal crystal or in the orthogonal crystal with the incident beams with some crystal axes than the CMS when the voltage is low.Thirdly, the EBSD patterns are firstly simulated by the RRS and the RS. Two methods are compared in detail with respect to different acceleration voltages of incident electron beams, temperature factors, incident beam aperture sizes. The results show that the RRS is more accurate for EBSD simulation than the RS.