Masters Theses

Abstract

"The effect of aging upon the dielectric constant and the dissipation factor were investigated for a number of lead titanate zirconate ceramics of varying composition. The ceramics investigated have a perovskite type structure. The materials chosen all have tetragonal symmetry at room temperature but are close in composition to materials of rhombohedral symmetry.

Empirical relations were determined for each specimen giving the rate of aging of the dielectric constant (K) and loss factor in terms of the frequency (f) and the elapsed time (t). The range of frequency was l kcps to l mcps; the range of elapsed time was from 2 hours to 2000 hours. The general expression for the change in dielectric constant with time was found to be dK/dt = (A log f - B) t, where A and B are positive constants, which were different for every one of the samples. During the period of measurement, the aging rate for dielectric constant was greatest at low frequencies.

The compositions showing greatest aging were those closest to the tetragonal-rhombohedral phase boundary. These were also the compositions with the highest dielectric constants and the lowest crystallographic c/a ratios.

No frequency dependence of aging has been reported before for perovskites ceramics. The time dependence found in this investigation is similar to those reported by other investigators previously for different ferroelectric materials"--Abstract p. ii

Advisor(s)

Gerson, Robert, 1923-2013

Committee Member(s)

Moore, Robert E., 1930-2003
Stettler, John Dietrich
Leighly, Hollis P., 1923-2004

Department(s)

Physics

Degree Name

M.S. in Physics

Publisher

University of Missouri at Rolla

Publication Date

1964

Pagination

vii, 70 pages

Note about bibliography

Includes bibliographical references (pages 68-69)

Rights

© 1964 Hector Troche-Maldonado, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 1554

Print OCLC #

5955142

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