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DF: Fachverband Dielektrische Festkörper

DF 7: Advanced Dielectrics

DF 7.5: Talk

Tuesday, March 24, 2009, 15:40–16:00, WIL A317

Lead-free ferroelectric solid solutions from first-principles calculations — •Silke Hayn, Melanie Gröting, and Karsten Albe — Materialwissenschaften, TU Darmstadt, Deutschland

Ferroelectric materials provide a link between electricity and mechanical movement. The technologically relevant materials, like PZT, are solid solutions which exhibit a morphotropic phase boundary (MPB). In an attempt to replace PZT by materials that do not contain toxic lead, a wide variety of solid solutions of lead-free perovskites is under investigation. First-principles calculations can be used to assist or even guide this search involving an enormous number of candidate materials.

In this contribution we present DFT calculations on K_xNa_1−xNbO₃, Bi_1/2Na_1/2TiO₃ (pure and doped with BaTiO₃), BaTiO₃ (pure and doped with BaZrO₃), and PbMg_1/3Nb_2/3O₃ and compare them with the standard material PZT. For all these materials cation displacements, tilt angles of oxygen octahedra and electronic transfer are evaluated. Further we investigate substitution effects, ordering and local distortion in detail and compare the results to experimental findings.