Aerosol Co-Deposition of Bi2O3 and TiO2 and in-situ formation of Bi4Ti3O12

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Exner, Jörg ; Fuierer, Paul ; Moos, Ralf:
Aerosol Co-Deposition of Bi2O3 and TiO2 and in-situ formation of Bi4Ti3O12.
2014
Veranstaltung: Electroceramics XIV , 16.-20.06.2014 , Bucharest, Romania.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung , Sonstige Präsentationstyp)

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Abstract

Bismuth titanate (Bi4Ti3O12) is a well known ferroelectric ceramic exhibiting a high Curie temperature (TC = 675°C) and offering possible applications like lead-free, high temperature, high-κ capacitor and piezoelectric devices. Our objective is to deposit Bi4Ti3O12 films by a novel spray coating method called aerosol deposition (AD or room temperature impact consolidation (RTIC)).

In contrast to common AD, we co-sprayed the starting materials (Bi2O3 and TiO2) together and achieved the final crystal structure by a subsequent heat treatment of the film (post-deposition calcination). Sprayed powders were prepared by mixing commercially available Bi2O3 and TiO2 powders (of stoichiometric ratio) in a planetary ball mill and dryed at 200°C. The AD process was performed using a custom-made AD apparatus. Resulting layers were investigated by SEM and high temperature XRD analysis.

Films of the Bi2O3/TiO2-mixture with thicknesses between 10 and 50 μm were deposited on alumina and silicon. Cross-sectional SEM-images reveal that harder TiO2-particles get embedded in a continuous Bi2O3-matrix during deposition leading to a dense compound layer (as-deposited state). By heat treating the film at 750°C for 5 h, the solid state reaction transforms the compound to a porous Bi4Ti3O12 layer.