HREM IMAGE-ANALYSIS BY FOURIER FILTERING OF REFLECTIONS WITH LONG EXTINCTION DISTANCES - APPLICATION TO THE SPINEL MGO SYSTEM/

It is known that high resolution electron microscopy can provide quant itative information on the nature of crystalline materials. In the pre sent paper an image processing technique is introduced that profits fr om long extinction distances in electron diffraction. It is applied to study the real structure of spinel films, which were grown on MgO sub strates by solid state reactions. The simulation of electron diffracti on and the analysis of calculated contrast tableaus revealed that the intensity of the spinel-specific {220} reflections is a monotonous fun ction of the crystal thickness in a wide range of parameters. Making u se of this relation experimental micrographs of spinel films and MgO/s pinel interfaces are interpreted by Fourier filtering. First, it is th e aim of the technique developed to map the local thickness of spinel films by evaluating the {220} related contrast. Second, if the specime ns are sufficiently plane, the degree of abruptness of the different s pinel/MgO reaction fronts can be analysed.