Domain Structures and Domain Wall Energies in Ferroelectric Guanidinium Aluminum Sulfate Hexahydrate

Fine details of ferroelectric domain structure in guanidinium aluminum sulfate hexahydrate have been revealed by an improved powder pattern technique. Within large positive or negative segments which correspond to growth pyramids, striation-type domains and small circular domains have been clearly resolved. Two types of the preferential wall orientation are characterized; one is parallel to the crystallographic symmetry planes, and the other is perpendicular to them. Spontaneous switching of many small domains has been found at low temperature (about 1.2×10 5 cm -2 at -100°C); they change in shape with lowering temperature from circle to hexagon with edges parallel to the symmetry planes. From an application of the Zhirnov-type continuum theory, the wall energy density is obtained as 0.3 erg/cm 2 , and is shown to be almost independent of wall orientation.