Microfields Induced by Random Compensated Charge Pairs in Ferroelectric Materials
Abstract
The dc and microwave responses of the Ba(x)Sr(1-x)(X,Y)Ti(1-y)O3 family of ferroelectric compounds with various substitutional additives X(3+), Y(5+) 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 Ti(4+) 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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 03, 2003
- Accession Number
- ADP013360
Entities
People
- Arthur Tauber
- Daniel M. Potrepka
- Frank J. Crowne
- Steven C. Tidrow
Organizations
- United States Army Research Laboratory