Structural Change in the Paraelectric Phase of Ammonium Rochelle Salt

摘要

The crystal structure of ammonium Rochelle salt inthe paraelectric phase are studied by X-ray diffraction. Systematicstructural changes are observed as a function of temperature. Hardlinks, which connect N ion, and oxygen O(8) with rigid tartrate, areextended in a plane parallel to the b-c plane. The oxygen of O(8)moves against a frame composed of N ions and the direction of thedisplacement is along the a-axis. The oxygens of O(9) and O(10)behave as a rigid body against the frame. These features are similarto these in the lower paraelectric phase of Rochelle salt.