Dislocations and Fine Lines in Rochelle Salt Crystal

Etch pits on c -face of rochelle salt were observed and it was concluded that they correspond to points where dislocations parallel to c -axis emerge on c -face. Some of the dislocations were found to be longer than several millimeters. Fine lines parallel to c -axis, called sudaré among Japanese researchers, were observed to be distributed in quite the same manner as dislocation etch pits are. Sudarés are observed at the deepest points of some etch pits. If surface energy of the interface between rochelle salt and its decomposed products be low, dislocation core may be opened and filled with the decomposed products. It seems likely that this open-cored dislocation may grow into the sudaré .