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MM: Fachverband Metall- und Materialphysik

MM 3: Computational Materials Modelling I

MM 3.4: Talk

Monday, March 14, 2011, 11:45–12:00, IFW B

Ab-initio and atomistic study of the ferroelectric properties of Cu doped potassium niobate — •Sabine Körbel and Christian Elsässer — Fraunhofer-Institut für Werkstoffmechanik IWM, Wöhlerstraße 11, 79108 Freiburg, Germany

KNbO₃ is one end member of the solid solution (K,Na)NbO₃ (KNN), which has promising ferroelectric properties to become a future lead-free substitute for lead zirconate titanate Pb(Zr,Ti)O₃ (PZT) in piezoelectric actors and sensors. Both KNN and PZT exhibit a phase transition with composition and a morphotropic phase boundary, at which enhanced piezoelectric coefficients are obtained. The material properties of PZT and KNN are commonly optimized by doping. E.g., CuO can be added when fabricating KNN as a sintering aid. Ab initio density functional theory and atomistic simulation using a classical shell model potential have been combined to investigate low Cu concentrations in the KNbO₃−CuNbO₃ system. The atomistic model predicts a morphotropic phase boundary at a few percent Cu, analoguous to the one found in the LiNbO₃−KNbO₃ system [1,2].

[1] Y. Guo, K. Kakimoto, and H. Ohsato, Appl. Phys. Lett. 85, 4121 (2004).

[2] D. I. Bilc and D. J. Singh, Phys. Rev. Lett. 96, 147602 (2006).