Dielectric Properties and Morphology of Ferroelectric Ceramic-Polymer Composite Films

Dielectric constant and morphology of BaTiO3-polymer composite films were studied as a function of the filler concentration. The morphology of the films was examined using laser scanning confocal microscopy, which is capable to measure small particle distributions in more details than conventional microscopy. The thin-slice images allowed us to visualize the micronsize particles and the polymer between them nondestructively. We have found that, although BaTiO3 particles appear to form clusters at low filler concentrations, the cluster formation does not affect the dielectric constant of the composites. INTRODUCTION High dielectric constant (High-K) ferroelectric ceramic-polymer composites have become potential candidate materials for integration into high frequency electronics. Detailed understanding of this class of materials will help electronic industry in planning, design and processing of these materials. We have synthesized a series of BaTiO3-polymer composites and measured their dielectric properties over a wide volume fraction of BaTiO3 filler [1]. BaTiO3 has been selected, because it is the best known ferroelectric ceramics. We have used photopolymerization method to keep the processing conditions simple and to obtain the composites as voids-free, two-component systems. In this paper, we report the microstructure of a series of composites, observed using laser scanning confocal microscopy (LSCM). There is much advantage in the use of LSCM over conventional microscopy techniques.[2,3] The LSCM affords visualization of smaller features than the conventional microscopy and with a better depth resolution, which allowed us to study the composite microstructure in details. EXPERIMENTAL Materials Trimethylolpropane triacrylate (TMPTA monomer) was purchased from Monomer Polymer & Dajac Labs. Barium titanate powder (BaTiO3 filler) and 2,2-dimethoxy-2-phenylacetophenone (photoinitiator) were obtained from Aldrich. All materials were used as received.[4] Sample Preparation Mat. Res. Soc. Symp. Proc. Vol. 682E © 2001 Materials Research Society