Influence of the A/B Stoichiometry on Defect Structure, Sintering, and Microstructure in Undoped and Cu-Doped KNN

  • Michael J. Hoffmann
  • Hans Kungl
  • Jérôme Acker
  • Christian Elsässer
  • Sabine Körbel
  • Pavel Marton
  • Rüdiger-A. Eichel
  • Ebru Erünal
  • Peter Jakes


Development of ceramics based on the alkaline niobate (KNN) system is one of the major lines of current research pointing to substitution of the lead containing ferroelectrics by lead‐free materials. Sodium potassium niobate (K0.5Na0.5)NbO3 is a prototype material of lead‐free alkaline‐transition metal ferroelectrics with \({\rm A}^{1+}{\rm B}^{5+}{\rm O}_3^{2-}\) perovskite structure. Processing procedures for KNN‐based ceramics are however challenging due to the hygroscopic behavior of sodium‐ and potassium carbonates and the evaporation of alkalines at the elevated processing temperatures, which make it difficult to control the stoichiometry of the ceramics. Alkaline (A‐site) or niobium (B‐site) excess results in pronounced qualitative differences of the microstructure in KNN ceramics.


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© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Michael J. Hoffmann
    • 1
  • Hans Kungl
    • 1
  • Jérôme Acker
    • 1
  • Christian Elsässer
    • 2
  • Sabine Körbel
    • 2
  • Pavel Marton
    • 2
  • Rüdiger-A. Eichel
    • 3
  • Ebru Erünal
    • 3
  • Peter Jakes
    • 3
  1. 1.Institute for Ceramics in Mechanical EngineeringKarlsruhe Institute of TechnologyKarlsruheGermany
  2. 2.Fraunhofer-Institut für Werkstoffmechanik IWMFreiburgGermany
  3. 3.Institut für Physikalische Chemie IFreiburgGermany

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