Studies on the Concentrated Steffen Fluid of Beet Sugar Industry. I. On the Salt Separated from Concentrated Steffen Fluid Using Methanol and Sulfuric Acid
Pressure-induced disordering of sodium potassium sulfates and chromates
作者:Frederick E. Bernardin、William S. Hammack
DOI:10.1103/physrevb.54.7026
日期:——
Raman scattering and energy-dispersive x-ray diffraction in a diamond-anvil cell were used to study the salts NaKSO4, K3Na(SO4)(2), NaKCrO4, and K3Na(CrO4)(2) to pressures of 22.5 GPa. These measurements reveal that the SO4 and CrO4 tetrahedra in the monopotassium salts become disordered while those in the tripotassium salts stay ordered. This disordering occurs without a significant change in the structural arrangement of the cations. We suggest that the disordering results from an impeded ferroelastic phase transition, which causes the zone boundaries, and therefore the SO4 and CrO4 tetrahedra, to be distorted, The four salts are related to one of two structures: The tripotassium salts are isostructural, the monopotassium salts are closely related. The two structures differ by one symmetry element, which leaves the neighboring tetrahedra inequivalent. It is this difference that causes only one of the structures to form distorted zone boundaries.