The effect of the type of power cycle upon the amount of output electrical work for a pyroelectric converter has been measured. Output electrical energy densities are reported for ceramic lead zirconate modified with Sn4+ and Ti4+ in the execution of a variety of thermal-electrical cycles. The effect upon the energy density due to changes in the voltage cycle limits and changes in the load resistance were also studied. A conversion cycle which is an electric analog of the Ericsson cycle is shown to yield the largest output energy density (100 mJ/cm3 for a 12.6 K temperature excursion and a 28-kV/cm electric field excursion).

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Copolymers of vinylidene fluoride-trifluoroethylene P(VDF-TrFE) exhibit large piezoelectric ~Qd pyroelectric effects. In addition to the most common application of the pyroelectric effect (radiant detection) it is possible to'convert heat directly into electrical energy by pyroelectric conversion. This study reports the first pyroelectric conversion cycle to be measured. for the ------,copolymer-F(VDF-1=r:FE) .. It-isfound-that-standard-isotheimal-D-E-hysteresis-loopmeasurements--------are not necessarily accurate predictors of pyroelectric conversion performance for-this material. Conduction effects are found to obscure the observation of conversion cycles in most cases for the presently available materials. In spite of these difficulties, a conversion cycle was measured whose output electric energy density was 30 mJ/cm 3 • The output density isI5 times larger than any other polymer previously measured. -

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Copolymers of vinylidene fluoride-trifluoroethylene P(VDF-TrFE) exhibit large piezoelectric and pyroelectric effects. In addition to the most common application of the pyroelectric effect (radiant detection) it is possible to convert heat directly into electrical energy by pyroelectric conversion. This study reports the first measurements of high (constant) field pyroelectric effects of P(VDF-TrFE) which are relevant to pyroelectric conversion. Electric displacement changes which result from temperature changes of the copolymer were measured for thermal cycling from room temperature to 90 °C at fields up to 1 MV/cm. The displacement changes (0.1–0.3 μ C/cm2) were dependent upon the molar ratio of the constituent monomers. The resistivity of the copolymer was also measured in the temperature range 20 to 90 °C and was found to vary from 1012 to 1016Ω cm depending on monomer ratio, temperature, field, and time. The resistivity and displacement change data are discussed in terms of predicted pyroelectric energy conversion performance.