CRYSTAL-STRUCTURE OF ROCHELLE SALT IN THE PARAELECTRIC PHASE

Temperature dependence of crystal structure of Rochelle salt is studie d by X-ray diffraction. As temperature decreased, the O(4) and O(3) at oms of the carboxylate anion have large displacement along the alpha-a xis. The oxygen O(8) has large displacement in the direction opposite to the shift of the carboxylate anion, as in the same displacement obs erved in the paraelectric phase of RS(0.72)ARS(0.28) mixed crystal.