Dresden 2014 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 9: Poster Session DF

DF 9.4: Poster

Tuesday, April 1, 2014, 18:30–20:00, P1

Vibrational properties of lithium niobate from density-functional perturbation theory — •Michael Friedrich, Arthur Riefer, Simone Sanna, Wolf Gero Schmidt, and Arno Schindlmayr — Department Physik, Universität Paderborn, 33098 Paderborn, Germany

Lithium niobate (LiNbO₃) is a dielectric crystal with outstanding electro-optical properties. It is characterized by a ferroelectric-paraelectric structural phase transition at 1480 K, which has been studied both theoretically and experimentally. Despite these investigations, the mechanisms of the phase transition are far from being understood. Although the phonon modes in relation to the ferroelectric instability are believed to play a crucial role, our actual knowledge of the phonon spectrum is limited to the center of the Brillouin zone. In order to shed light on the lattice dynamics leading to the ferroelectric transition, we have modeled the vibrational properties of LiNbO₃ within the density-functional perturbation theory. In this work we present the full phonon dispersion of both the ferroelectric and the paraelectric phases.