Masters Theses

Abstract

"Substitution of Mn and Co on the B site of YCrO3 was investigated using XRD, dilatometry and D.C. electrical conductivity. Except for compositions with more than 60 mol% Co and with 80 mol% or greater Mn, compositions of the ternary system Y1.00 Cr1.00-x-y Mnx CoY O3 were of orthorhombic (pseudo-perovskite) phase based on XRD of powders calcined in air at 1100°C. Unit cell volumes decreased for compositions with high Co contents, approaching the reported value of YCoO3. Cobalt was a good sintering aid in air, with 20 mol% Co compositions sintering to close to 90% relative density in air at 1500°C. Addition of up to 60 mol% Co allowed the sintering temperature to be reduced to 1350°C, while maintaining the orthorhombic phase. Electrical conductivity increased incrementally as Co content increased due to the addition of charge carriers from the Co species. A good fit to the adiabatic small polaron mobility relation was shown. Activation energies decreased as Mn was added. The linear thermal expansion coefficient of test specimens increased as Co content of the compositions increased for a constant Mn content. Evidence of an impurity phase was seen at the grain boundaries in micrographs of most of the test specimens"--Abstract, page iii.

Advisor(s)

Anderson, H. U. (Harlan U.)

Committee Member(s)

Moore, Robert E., 1930-2003
Sparlin, Don M.

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Ceramic Engineering

Publisher

University of Missouri--Rolla

Publication Date

Fall 1994

Pagination

xi, 121 pages

Note about bibliography

Includes bibliographical references (pages 117-120).

Rights

© 1994 Stephen Mark Seward, All rights reserved.

Document Type

Thesis - Restricted Access

File Type

text

Language

English

Thesis Number

T 6893

Print OCLC #

33212421

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