"Thermal expansion and transformations of K2SO4, K2CrO4, K2MoO4, and K2WO4 were studied by high temperature diffractometry, differential thermal analysis, and dilatometry. K2SO4 and K2CrO4 transform from an orthorhombic to a hexagonal structure at 580°C and 670°C respectively, with initiation of the transformation probably related to increased amplitude of S-O tetrahedral vibrations. K2MoO4 and K2WO4 transform from a monoclinic to an orthorhombic structure at 300° and 370°C respectively. A minor K2MoO4 transformation between the orthorhombic and hexagonal phases was found at 450°C. K2WO4 shows similar minor transformations at 450° and 600°C.
The systems K2SO4-K2CrO4, K2SO4-K2MoO4, K2SO4-K2WO4, K2CrO4-K2MoO4, K2CrO4-K2WO4, and K2MoO4-K2WO4 were studied. The K2SO4-K2CrO4 and K2MoO4-K2WO4 systems show complete solubility with linear variations of the transformation temperatures with composition. The remaining systems show partial solubility with eutectoids. Eutectoids in the sulfate systems are at approximately 310°C, 80% K2MoO4 and 350°C, 60% K2WO4. In the chromate systems, eutectoids are approxiamately 300°C, 70% K2MoO4, and 375°C, 70% K2WO4. Complete solubility of all high temperature hexagonal phases was observed.
Structural relationships were shown and possible transition mechanisms were suggested"--Abstract, page ii.
Sorrell, Charles A.
Moore, Robert E., 1930-2003
James, William Joseph
Anderson, H. U. (Harlan U.)
Materials Science and Engineering
Ph. D. in Ceramic Engineering
University of Missouri--Rolla. Ceramic Engineering Department
University of Missouri--Rolla
xii, 221 pages
© 1974 Roy Richard Ramey, All rights reserved.
Dissertation - Open Access
Ceramic materials -- Thermal properties
Phase transformations (Statistical physics)
Print OCLC #
Electronic OCLC #
Link to Catalog Record
Ramey, Roy Richard, "Phase equilibria and transformations in potassium sulfate, chromate, molybdate, and tungstate" (1974). Doctoral Dissertations. 288.