Ferroelectric properties of composites containing BaTiO3 nanoparticles of various sizes

• Published in: Nanotechnology Vol. 25; no. 6; p. 065704
• Main Authors: Adam, Jens, Lehnert, Tobias, Klein, Gabi, McMeeking, Robert M
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 14.02.2014; Institute of Physics
• Subjects: BaTiO; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; ferroelectric; Materials science; Nanocrystalline materials; nanoparticles; Nanoscale materials and structures: fabrication and characterization; Physics; size effect; Nanoparticles; Electrical measurement; Particle size; Composite materials; Ferroelectric materials; Electric field effects; Coercive force; Size effect; Permittivity; Nanostructured materials; Ferroelectric thin films
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/0957-4484/25/6/065704

Size effects, including the occurrence of superparaelectric phases associated with small scale, are a significant research topic for ferroelectrics. Relevant phenomena have been explored in detail, e.g. for homogeneous, thin ferroelectric films, but the related effects associated with nanoparticles are usually only inferred from their structural properties. In contrast, this paper describes all the steps and concepts necessary for the direct characterization and quantitative assessment of the ferroelectric properties of as-synthesized and as-received nanoparticles. The method adopted uses electrical polarization measurements on polymer matrix composites containing ferroelectric nanoparticles. It is applied to ten different BaTiO3 particle types covering a size range from 10 nm to 0.8 μm. The influence of variations of particle characteristics such as tetragonality and dielectric constant is considered based on measurements of these properties. For composites containing different particle types a clearly differing polarization behaviour is found. For decreasing particle size, increasing electric field is required to achieve a given level of polarization. The size dependence of a measure related to the coercive field revealed by this work is qualitatively in line with the state of the knowledge for ferroelectrics having small dimensions. For the first time, such results and size effects are described based on data from experiments on collections of actual nanoparticles.