Hydroxyl Defect Effect on Reoxidation of Sc‐Doped (Ba,Ca)(Ti,Zr)O3 Fired in Reducing Atmospheres |
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| Authors: | Yu‐Ju Kao Che‐Yi Su Christian Pithan Detlev F. Hennings Chi‐Yuen Huang Rainer Waser |
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| Affiliation: | 1. Department of Resources Engineering, National Cheng Kung University, Tainan, Taiwan;2. Peter Grünberg Institut, PGI‐7: Electronic Materials, Forschungszentrum Jülich GmbH, Jülich, Germany;3. Institut für Werkstoffe der Elektrotechnik II, RWTH Aachen, Aachen, Germany |
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| Abstract: | The behavior of grain and grain‐boundary conductivity of acceptor (Sc)‐doped (Ba,Ca)(Ti,Zr)O3 ceramics sintered in moist reducing atmosphere and subsequently reoxidized in dry and moist atmosphere was investigated by means of impedance spectroscopy (IS). In moist firing atmosphere, water vapor was found to react with oxygen vacancies, forming positively charged hydroxyl defects  on regular oxygen sites in the crystal lattice. Proton hopping is considered to raise the ionic conductivity significantly. Therefore, hydroxyl defects  in turn influence the grain conduction. Hydroxyl defects  are also considered to be responsible for alternations of the dielectric maximum at the Curie point. |
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