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Journal of Materials Science

, Volume 29, Issue 18, pp 4686–4693 | Cite as

Formation of barium-tantalum oxynitrides

  • A. Hellwig
  • A. Hendry
Papers

Abstract

Oxynitride powders suitable for sintering to form dielectric ABO3-type perovskites have been prepared by nitriding barium carbonate and tantalum oxide. Both heat treatment in air and reaction in flowing ammonia yield isostructural oxynitride phases, but the amount and electronic state of the oxynitrides depend on the nitriding gas conditions. A red-brown oxynitride of high nitrogen content is described as Ba2Ta2O3N2 containing Ta (IV) ions, but after heat treatment in air the colour changes to white indicative of Ta(V) and a stoichiometry of BaTaO2N results. A third possibility is identified in an oxynitride containing both Ta (IV) and Ta (V) with an intermediate nitrogen content. Through studies involving thermal analysis and X-ray diffraction, the materials are characterized in powder form and possible sintering conditions are suggested which involve a rapid heating rate and a densification temperature of 1500 °C.

Keywords

Heat Treatment Barium Perovskite Nitrogen Content Tantalum 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • A. Hellwig
    • 1
  • A. Hendry
    • 1
  1. 1.Department of Metallurgy and Engineering MaterialsUniversity of StrathclydeGlasgowUK

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