Regensburg 2010 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 8: Electrical and mechanical properties

DF 8.3: Talk

Tuesday, March 23, 2010, 14:40–15:00, H9

Ab initio simulation of copper dopants and vacancies in the lead-free ferroelectric potassium sodium niobate — •Sabine Körbel and Christian Elsässer — Fraunhofer-Institut für Werkstoffmechanik IWM, Wöhlerstraße 11, 79108 Freiburg

Lead-free ferroelectric ceramics, for instance the perovskite potassium sodium niobate (KNN), are regarded as potential future alternatives to the widely used lead zirconate titanate (PZT) for piezoelectric applications. These materials can be doped with various elements in order to optimize their ferroelectric properties for the respective application. In the case of KNN, copper oxide can be added during processing as a sintering aid.

In this work, the influence of metal impurities on the ferroelectric properties of KNN is investigated for the example of Cu. By means of ab initio density functional theory, we determined the prevailing point defect types and the preferred lattice sites of Cu dopants for different processing conditions, and the stability of dopant-vacancy complexes.

In order to study the influence of point defects on switching the ferroelectric polarization of KNN, we investigated the effect of Cu on the energy needed for switching between different polarization directions.