Accession Number:

ADA324581

Title:

First-Principles Calculations for Ferroelectrics.

Descriptive Note:

Final rept. 1 Nov 93-31 Dec 96,

Corporate Author:

COLLEGE OF WILLIAM AND MARY WILLIAMSBURG VA DEPT OF PHYSICS

Personal Author(s):

Report Date:

1997-05-01

Pagination or Media Count:

8.0

Abstract:

First-principles calculations for ferroelectrics reveal the existence of extended instabilities as a function of wavevector in KNbO3 and SrTiO3. The scope of the first-principles results is extended through the use of effective Hamiltonians, determined with no empirical or experimental input, using a database of first-principles calculations. Molecular dynamics simulations using these effective Hamiltonians then predict ferroelectric phase transition temperatures, phonon softening, and diffuse X-ray scattering behavior. These calculations also demonstrate for the first time the existence of preformed dynamic precursor chain-like structures in KNbO3 and BaTiO3, well above the ferroelectric transition temperatures.

Subject Categories:

  • Inorganic Chemistry
  • Ceramics, Refractories and Glass
  • Electricity and Magnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE