Ferroelectric ceramics: defects and dielectric relaxations

• Published in: Journal of materials chemistry Vol. 11; no. 8; pp. 1957 - 1967
• Main Authors: ELISSALDE, C, RAVEZ, J
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2001
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Dielectric loss and relaxation; Dielectric properties of solids and liquids; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Niobates, titanates, tantalates, pzt ceramics, etc; Physics; Structure of solids and liquids; crystallography; Ferroelectric ceramics; Frequency dependence; Domain walls; Defects; Dielectric relaxation
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/b010117f

Dielectric relaxations in ferroelectric ceramics occur at various frequencies, depending on the type of chemical or physical defects. These defects depend on either intrinsic or extrinsic heterogeneities due to special heat treatments (quenching, annealing, etc), ionic substitutions, grain size additives, and grain boundary nature. The value of the relaxation frequency fr increases from about 100-10 exp(12) Hz as the scale of the defect phenomenon decreases from microstructure, to nanostructure, to unit-cell, to atomic vibrations. This type of study requires a pluridisciplinary approach involving solid state chemistry, materials science, solid state physics and various industrial aspects. The applications in the area of electronic ceramics are related to the value of fr. In absorbents, the usable frequency is close to fr, whereas it is far from fr in good insulators. In view of numerous experimental examples, a classification is proposed to predict which materials may be suitable for a given application. 92 refs.