Dielectric and Pyroelectric Properties of (Ba,Sr,Ca)TiO3 Ceramics for Uncooled Infrared Detectors

概要

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(Ba0.6Sr0.3Ca0.1)TiO3 (BSCT) powders, which were prepared by the sol–gel method using a solution of Ba, Sr and Ca acetate and Ti isopropoxide, were spray-dried under the optimum conditions of a 10000 rpm atomizer speed and 1.5 wt% polyvinyl alcohol (PVA) addition. BSCT ceramics, undoped and doped with MnCO3 (0.1 mol%) and Y2O3 (0–0.9 mol%), were fabricated by the cold isostatic press method, and then the structural and electrical properties as a function of the Y2O3-dopant amount were studied. The specimen, doped with more than 0.5 mol% Y2O3, showed small and uniform grains of 1–3 $\mu$m in diameter. The Curie temperature and the maximum dielectric constant decreased with increasing Y2O3 content and the dielectric loss of the specimen, doped with 0.5 mol% Y2O3, showed a minimum value of 0.009 at the Curie temperature. The pyroelectric coefficient decreased as the dopant of Y2O3 increased and the doped specimen of 0.3 mol% Y2O3 showed a good value of $354 \times 10^{-9}$ C/cm2K under a 4 kV/cm DC bias field. The figure of merit F.M.D* for specific detectivity (D*) of the specimen, doped with 0.5 mol% Y2O3, showed the highest value of $8.9 \times 10^{-9}$ Ccm/J.
2000-08-15