Nanostructured barium titanate composites for embedded radio frequency applications

We describe a vapor-phase codeposition method to fabricate a ceramic-in-polymer composite system comprising ferroelectric barium titanate nanoparticles in a highly polarizable polyaniline-polyurethane copolymer host. As-deposited composites exhibited a capacitance density of 15 nF/cm(2) and a resonance frequency close to 100 MHz with a loss tangent of 0.8. Annealing nanocomposites at 135 degrees C resulted in slightly reduced but frequency-independent capacitance density (similar to 10 nF/cm(2)) with a loss tangent of 0.1 and resonance frequency at 200 MHz. The interplay of polarization modes is discussed in relation to capacitor performance. The fabricated capacitors have potential for applications in embedded technology in the radio frequency. (C) 2007 American Institute of Physics.