This thesis presents an investigation of the conduction mechanism in the La1-yCayAl1-xMnxO3 perovskite system. This system allows a detailed study of site percolation in which small polarons hop among nearest neighbor Mn sites because the small polarons are restricted to the Mn sites as the Al ions are incapable of supporting small polarons.
Electrical conductivity and Seebeck coefficient measurements were carried out as a function of temperature for the LaAl1-xMnxO3 series and the La0.79Ca0.2Al1-xMnxO3 series in which 20 mol% Ca was substituted for La. The conductivity results for both series indicate that this system can be related to a site percolation model in which conduction occurs via hopping of small polarons among the Mn sites. The Seebeck data indicates that thermally activated Mn2+- Mn4+ pairing occurs from the Mn3+ state in these systems. Measured high temperature Seebeck coefficients for these systems were near zero for Mn concentrations above the percolation limit. Reproducible, but unexplained, results were observed for Mn concentrations below the percolation threshold in the Ca-doped series.
Anderson, H. U. (Harlan U.)
Sparlin, Don M.
Nasrallah, Magdi M.
Materials Science and Engineering
M.S. in Ceramic Engineering
University of Missouri--Rolla
Journal article titles appearing in thesis/dissertation
Conduction Mechanism in the La(Al,Mn)O3 System
vii, 68 pages
© 1991 Michael Joseph DeBarr, All rights reserved.
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Electronic access to the full-text of this document is restricted to Missouri S&T users. Otherwise, request this publication directly from Missouri S&T Library or contact your local library.http://merlin.lib.umsystem.edu/record=b2440131~S5
DeBarr, Michael Joseph, "Investigation of the conduction mechanism in La1-yCayAl1-xMnxO₃" (1991). Masters Theses. 1032.
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