Accession Number:

ADP013360

Title:

Microfields Induced by Random Compensated Charge Pairs in Ferroelectric Materials

Descriptive Note:

Conference proceedings

Corporate Author:

ARMY RESEARCH LAB ADELPHI MD RF ELECTRONICS DIV

Report Date:

2003-04-03

Pagination or Media Count:

12.0

Abstract:

The dc and microwave responses of the BaxSr1-xX,YTi1-yO3 family of ferroelectric compounds with various substitutional additives X3, Y5 are analyzed by combining the random-field technique with the mean-field Landau-Devonshire theory of ferroelectricity, along with a self consistent computation of the dielectric constant of the host material in the presence of the impurity fields. The fields in the material are assumed to arise from charge compensation at the Ti4 sites, leading to permanent dipoles made up of the resulting positive and negative ions separated by a few lattice constants. It is shown that whereas completely random placement of positive and negative ions generates a Holtsmark distribution of electric field, with infinite second moment and hence extremely large fluctuations in field strength, the association of ionized impurities into permanent dipoles leads to much lower fluctuations in field and a distribution with finite second moment, which makes a self-consistent dielectric constant meaningful.

Subject Categories:

  • Physical Chemistry
  • Electricity and Magnetism
  • Radiofrequency Wave Propagation

Distribution Statement:

APPROVED FOR PUBLIC RELEASE