Viscoplastic models for ferroelectric ceramics

• Published in: Journal of the European Ceramic Society 2005, Vol.25 (12), p.2567-2571
• Main Authors: Belov, A.Yu, Kreher, W.S.
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Defects; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Electrotechnical and electronic ceramics; Exact sciences and technology; Ferroelectric properties; Modelling; Niobates, titanates, tantalates, pzt ceramics, etc; Physics; Plasticity; PZT; Technical ceramics
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2005.03.102

Nonlinear hysteretic phenomena in polycrystalline ferroelectric ceramics are simulated using viscoplastic (rate-dependent) models without a switching condition. Viscoplastic models describe the domain structure evolution effectively: in terms of rate equations for the volume fractions of orientation variants. The results of a comparative study of two viscoplastic models for polycrystalline ferroelectrics undergoing a cubic-to-tetragonal phase transition are discussed. Both models allow for 90 and 180° polarization switching, but differ in the number of accessible domain orientations, which is 6 and 42, respectively. While the model with 6 polarization orientations provides a reasonable description of ferroelectric ceramics under uni-axial loading, the model with 42 orientations reproduces the typical isotropic behaviour of polycrystalline materials and can be parameterized for multi-axial loading. Examples of the viscoplastic models application to rate-dependent phenomena in soft PZT ceramics and to a 3D finite element analysis of microstructural inhomogeneities in ferroelectric multi-layer films are given.