Thin pyroelectric composite films have been fabricated in which both phases are electroactive. Triglycine sulphate crystals, grown by freezing an aqueous solution at various rates and freeze-drying the resultant solid mass, were mixed (10% w/w) with a solution of 70:30 vinylidene fluoride:trifluoroethylene copolymer in butanone and films were produced by spin-coating. The best material possessed a pyroelectric coefficient of (60 ± 2) μCm-2 K-1 and a figure of merit (pyroelectric coefficient/✓ (relative permittivity × dielectric loss)) of 150 μCm-2 K-1, some 18% and 35% larger, respectively, than the corresponding values for the copolymer alone.
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Department of Physics, Loughborough University of Technology, Loughborough, Leicestershire, UK
Department of Chemistry, University of Portsmouth, Portsmouth, Pol 2DT, UK