Evaluation of characterization methods for thin sections of silver halide microcrystals by analytical electron microscopy

Silver halide microcrystals are usually composed of different phases with varying halide compositions. These microcrystals can be sectioned with an ultramicrotome with a certain thickness in a specific direction, The scanning electron microscopical analysis of these sections provides information on the internal halide profile. During sample sectioning, many deformations can be induced in the material, and usually dominate the different scanning electron images. By acquiring X-ray maps, it is possible to locate the different phases in the sections, This technique, however, is very time-consuming, and can only be used when the local halide variations are very high. When an EDX line scan is acquired over the section, information on the position of the phases with different halide composition is obtained in a reasonable time, and shows no dependence on the section deformations, From this knowledge, several positions on the section are selected where local X-ray analyses are performed. After quantifying the results, the internal halide distribution is obtained, The analytical lateral resolution is about 30 nm for sections approximate to 100 nm thick.