This week I got to observe as SEM was performed on some of my samples. The following picture is of the sputter coating procedure done before the actual SEM is used. The material I am working with is not conductive, so when the electrons from the electron beam hits the material, it traps the electrons and causes charging. This charging can cause bright white patches in the images, or streaks across them. To sputter coat, the samples are placed on a holder and sealed in a chamber under argon gas and a fine layer of gold, ~10nm, is dispersed over the sample. The SEM uses a focused ion beam to scan the material, based on how the electrons interact with the material it gives back information of the topography and gives an image.
Sputter Coating the samples with gold
The images are especially useful to establish the correlation between the process of autoclaving the materials, and the size and crystallinity of the substances used. One of the questions I am considering is whether autoclaving the powders will increase the removal of selenium. The SEM helps to visually observe the difference in structure between the materials being considered.
Mg2Al LDH before autoclave at 20,000x magnification
Mg2Al after the autoclave, at a higher magnification of 150,000x
Zn2Al LDH after autoclave at 50,000x magnification