Doctoral Dissertations

Abstract

"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.

Advisor(s)

Sorrell, Charles A.

Committee Member(s)

Moore, Robert E., 1930-2003
James, William Joseph
Anderson, H. U. (Harlan U.)
Lewis, Gordon

Department(s)

Materials Science and Engineering

Degree Name

Ph. D. in Ceramic Engineering

Sponsor(s)

University of Missouri--Rolla. Ceramic Engineering Department

Publisher

University of Missouri--Rolla

Publication Date

1974

Pagination

xii, 221 pages

Note about bibliography

Includes bibliographical references (pages 178-181).

Rights

© 1974 Roy Richard Ramey, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Ceramic materials -- Thermal propertiesPhase transformations (Statistical physics)Phase diagrams

Thesis Number

T 3032

Print OCLC #

6013161

Electronic OCLC #

914167297

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