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Powders, fibers, thin films and aerogels: Sol-gel-derived piezoelectric materials

 
: Löbmann, P.; Lange, U.; Glaubitt, W.; Hutter, F.; Sporn, D.

Gong, J.:
High-performance ceramics 2001 : Proceedings of the Second China International Conference on High-Performance Ceramics (CICC-2), Kunming, China, November 11 - 15, 2001
Uetikon-Zürich: Trans Tech Publications, 2002 (Key engineering materials 224/226)
ISBN: 0-87849-897-4
S.613-618
China International Conference on High-Performance Ceramics (CICC) <2, 2001, Kunming>
Englisch
Konferenzbeitrag
Fraunhofer ISC ()
Dünnfilm; Aerogel; PZT; Solgel

Abstract
Sol-gel processing allows the fabrication of high quality ceramic materials as powders, films, fibers and aerogels, which by other techniques is costly, difficult or even impossible. For perowskite-phase electroceramics precise control over the stoichiometric composition of the materials and easy introduktion of donpants are additional advantages of preparation from chemical precursors. In this lecture a survey of PZT ceramics manufactured in different morphologies by sol-gel processing is presented.
Precursor powders for thin films were synthesized by the reaction of zirconium- and titanium-n-propoxides with acetylacetone and lead acetate trihydrate. Coating sols can be obtained by dissolution of these powders in various solvents and solvent mixtures. PZT films with a maximum thickness of 8 um are prepared by multiple dip-coating and subsequent firing at 700°C.
PZT fiberscan be attractive both for sensor and actuator applications in composite materials. Fibers are drawn in a cotinuous process directley from spinnable sol-gel precursors. After pyrolysis and sintering the fibers are embedded into polymer resins. The resulting composites were already sucessfully tested as sensor elements.
In a sol-gel process utilizing an emulsion technique PZT precursor powders may be obtained for conventional ceramic processing. The final products manufactured by e.g. tape-casting and firing exhibit improved properties compared to mixed-oxide derived materials with the same composition.
For ultrasonic applications in gases porous piezoelectric transducers with low acoustic impedances are required. Highly porous PZT aerogels can be prepared by sol-gel processing, supercritical drying and subsequent thermal curing. The drying conditions applied have a pronounced effect on the properties and microstructure of the final porous ceramics.

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