Accession Number:

AD0832976

Title:

ORDER-ORDER PHASE TRANSISTIONS IN FERROELECTRICS.

Descriptive Note:

Special rept. Jan-Dec 67,

Corporate Author:

OXFORD UNIV (UNITED KINGDOM) CLARENDON LAB

Personal Author(s):

• Elliott, R. J.
• Krumhansl, J. A.

Report Date:

1968-02-01

Pagination or Media Count:

30.0

Abstract:

The current theories of ferroelectric phase transitions are reviewed with particular reference to the form of the excitations. Since a well defined order exists both above and below Tc one expects these to have meaning in both phases. The unharmonic phonon model of pevovskites and the pseudo-spin model of KH2PO4 are considered in detail, and the similarities remarked on. The main problems centre on the damping of the excitations particularly close to Tc in the initial region. Neither theory nor experiment gives a refined view of this question. Author

Descriptors:

• *FERROELECTRIC CRYSTALS
• PHASE STUDIES
• TRANSITION TEMPERATURE
• PEROVSKITES
• HYDROGEN COMPOUNDS
• PHOSPHATES
• PHONONS
• DEFECTS(MATERIALS)

Subject Categories:

• Crystallography
• Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE