Oxygen nonstoichlometry and dielectric evolution of BaTiO 3. Part I - Improvement of insulation resistance with reoxidation

G. Y. Yang, E. C. Dickey, C. A. Randall, D. E. Barber, P. Pinceloup, M. A. Henderson, R. A. Hill, J. J. Beeson, D. J. Skamser

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Impedance spectroscopy, transmission electron microscopy, and electron energy-loss spectroscopy are used to correlate local electrical properties with the microstructure and microchemistry of BaTiO 3 in Ni-electrode multilayer ceramic capacitors. High densities of linear defects and some grains with structural modulations are observed in BaTiO 3 grains in the as-cofired capacitors. The modulated structure is formed on {111} planes of the BaTiO 3. Both types of structural defects are associated with high concentrations of oxygen vacancies. In particular, the oxygen content in the BaTiO 3 grains that are in direct contact with the internal Ni electrodes is less uniform with a systematic decrease in oxygen content towards the electrode. In the capacitors that are reoxidized in a higher oxygen partial pressure at lower temperature, the BaTiO 3 grains are almost free of linear defects and structural modulations and the oxygen content is homogeneous throughout the BaTiO 3 active layers. A concomitant improvement in the total insulation resistance is observed.

Original languageEnglish (US)
Article number8
Pages (from-to)7492-7499
Number of pages8
JournalJournal of Applied Physics
Issue number12
StatePublished - Dec 15 2004

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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