QUANTITATIVE CRITERIA FOR THE DETECTION AND CHARACTERIZATION OF NANOCRYSTALS FROM HIGH-RESOLUTION ELECTRON-MICROSCOPY IMAGES

A new method of high-resolution electron microscopy image analysis is presented which improves considerably the visibility of nanocrystals in amorphous materials. The technique is based on individual Bragg filtering of the lattice fringes in the image. The significant feature is that the amplitude and phase of the fringes as functions of position are calculated separately. This is similar to a holographic reconstruction with the Bragg interference representing the carrier wave. The phase information is shown to be particularly robust with respect to noise due to amorphous material. The images so produced are in a form suitable for statistical analysis, and criteria for judging quantitatively the extent of the crystal are proposed. The application of the technique to a wide range of similar problems concerning partially ordered materials is discussed.