QUANTITATIVE COMPARISON OF TEM TECHNIQUES FOR DETERMINING AMORPHOUS INTERGRANULAR FILM THICKNESS

The question of which transmission electron microscopy technique can b est be used to quantitatively determine the thickness of thin intergra nular films is addressed. Measurement of the film thickness by diffuse dark-field imaging resulted in values 50% to 100% larger than those d etermined by high-resolution lattice imaging. Defocus Fresnel fringe i maging is an indirect method of obtaining intergranular film thickness ; with this method thicknesses were over-estimated by 20% to 35%, with the largest error caused by uncertainty in the exact location of frin ge maxima. Although technically difficult to use, high-resolution latt ice imaging is a method capable of the resolution necessary to obtain detailed information of the boundary and the intergranular phase itsel f; it was found to be the most applicable to quantitative measurements of film thicknesses in Si3N4 materials, with an accuracy of +/- 1 ang strom (+/- 0.1 nm).