QUANTITATIVE MEASUREMENT OF DISPLACEMENT AND STRAIN FIELDS FROM HREM MICROGRAPHS

A method for measuring and mapping displacement fields and strain fiel ds from high-resolution electron microscope (HREM) images has been dev eloped. The method is based upon centring a small aperture around a st rong reflection in the Fourier transform of an HREM lattice image and performing an inverse Fourier transform. The phase component of the re sulting complex image is shown to give information about local displac ements of atomic planes and the two-dimensional displacement field can be derived by applying the method to two non-colinear Fourier compone nts. Local strain components can be found by analysing the derivative of the displacement field. The details of the technique are outlined a nd applied to an experimental HREM image of a domain wall in ferroelec tric-ferroelastic PbTiO3. (C) 1998 Elsevier Science B.V. All rights re served.