Study of ferroelectric domains on G.A.S.H. single crystals by the scanning electron microscope

The ferroelectric properties of guanidine aluminium sulphate hexahydrate (G.A.S.H.) were discovered in 1955 (1). The polar axis was found to be perpendicular to the natural cleavage plane. The domain structure of G.A.S.H. have been observed by Pearson and Feldman (2) by pulver technique, Yuri at al. (3) by electroluminescence and B. Hilczer at al. (4-5) by electron microscope decoration techniqueWe study domain structure in G.A.S.H. single crystals whithout metallization with a scanning electron microscope (S.E.M.). Figure 1 shows the observations obtained on a no etched crystal observed with a scanning electron microscope in the secondary electron emission mode; we see a domain. When the accelerating voltage Vacc of the incident beam pass from 2.3 KV. to 5 KV. the contrast between domains is inversed. At 3.5 KV. the contrast is the same that at 5 KV. but the domain wall is more precise. The inversion of contrast is obtained between 3.3 KV. and 3.4 KV. ; and in this inversion zone we have not any contrast due to the domain or to its boundary.