Masters Theses

Abstract

"The purpose of this investigation was to conduct a crystallographic study of the PbZrO₃-PbTiO₃-BiFeO₃ ternary system, where all three components are perovskites. Lead zirconate is antiferroelectric, lead titanate is ferroelectric, and bismuth ferrate is thought to be ferroelectric. X-ray diffraction analysis was employed to determine the crystallographic structure and lattice parameters.

A tetragonal region was found to exist in the area of high PbTiO₃ content. A rhombohedral region occurred in the remainder of the system with high BiFeO₃ and PbZrO₃ content, except for an orthorhombic envelope along the PbZrO₃-BiFeO₃ side of the diagram up to approximately 70 per cent BiFeO₃.The phase boundaries in the system had a phase width, rather than being distinct lines.

The addition of PbZrO₃ to the binary PbTiO₃-BiFeO₃ suppresses the normally increasing c/a ratio which occurs as the BiFeO₃ content is increased. At 50 PbZrO₃:5O PbTiO₃, the addition of BiFeO₃ decreases this ratio.

The orthorhombic region near the PbTiO₃-BiFeO₃ binary was indexed using a multiple-cell orthorhombic structure. All three lattice parameters decreased with additions of BiFeO₃.

High resolution conditions on the diffractometer were required to determine the peak splitting on most of the rhombohedral x-ray patterns. The rhombohedral distortion increased and the "a" parameter decreased with increasing BiFeO₃ content.

The dielectric constant and Curie point were determined for various ratios of BiFeO₃ and 50 PbZrO₃ :50 PbTiO₃. The Curie point was found to be 380 and 400°C for 20 and 30 per cent BiFeO₃, respectively. For 20 per cent BiFeO₃, a dielectric constant of 685 was ascertained. The present study finds significantly higher electrical properties than those reported previously"--Abstract, pages ii-iii.

Advisor(s)

Johnson, James W., 1930-2002

Committee Member(s)

Park, Efton
Gerson, Robert, 1923-2013
Tappmeyer, Wilbur P.

Department(s)

Chemical and Biochemical Engineering

Degree Name

M.S. in Chemical Engineering

Sponsor(s)

U. S. Atomic Energy Commission

Publisher

University of Missouri at Rolla

Publication Date

1966

Pagination

viii, 60 pages

Note about bibliography

Includes bibliographical references (pages 29-30).

Rights

© 1966 Dannie R. Clarida, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Library of Congress Subject Headings

Perovskite
Ferroelectric crystals
Antiferromagnetism

Thesis Number

T 1922

Print OCLC #

5977332

Electronic OCLC #

908550593

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