Nanostructure, Defect Chemistry and Properties of Relaxor Ferroelectrics
Abstract
This research focused on cation ordering, defect chemistry, and dielectric properties of the BaTiO3-Ba(Zn1/3Nb2/3)O3 (BZN) system. The latter compound was chosen as an analog of the PbO-based relaxor ferroelectrics to avoid the severe experimental restrictions caused by the volatility and reducibility of PbO. Two types of ordering of the Zn and Nb content of BZN were observed; a 1:1 (alternate layer) type that represents a local compositional change and charge imbalance that restricts the size of ordered domains, and a 1:2 type that is consistent with the composition of BZN. The effects of the Zn/ Nb ratio and doping on the type and extent of ordering were determined. The defect chemistry of BZN is closely related to that of BaTiO3, which has been well-characterized. The material usually contains a large concentration of extrinsic oxygen vacancies because of compositional variations and ZnO loss. Mass-action expressions and thermodynamic parameters of the oxidation and reduction reactions, and of the band gap were determined. The proposed defect model is in excellent quantitative agreement with the experimental observations. The evolution of dielectric properties was studied as the Ti content of BaTiO3 was gradually replaced by Zn1/3Nb2/3.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1992
- Accession Number
- ADA247294
Entities
People
- D. M. Smyth
- M. P. Harmer
Organizations
- Lehigh University