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DF: Fachverband Dielektrische Festkörper

DF 6: Poster I

DF 6.8: Poster

Dienstag, 24. März 2009, 09:30–12:30, P5

Structure and Physical Properties of A_2/3Cu₃Ti₄O₁₂ (A = Rare Earth) — •Stefan Riegg¹, Jürgen Sebald³, Stephan Krohns³, Stefan G. Ebbinghaus², Peter Lunkenheimer³, Alois Loidl³, and Armin Reller¹ — ¹Solid State Chemistry, Institute for Physics, University of Augsburg, 86135 Augsburg, Germany — ²Solid State Chemistry, Institute for Chemistry, Martin-Luther University Halle-Wittenberg, 06120 Halle, Germany — ³Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany

Many materials based on the ACu₃Ti₄O₁₂ structure-type provide very high dielectric constant ε′, like the most famous member A = Ca with a value of greater than 10³. These materials with so called "collossal dielectric constants" (CDC) are very useful for technical application and thus of special scientific interest. Structurally related systems with lanthanide ions on the A position can be used to study the CDC mechanism. Due to the +3 (Ce: +4) valence of the rare earth ions, in comparison to the +2 valence of Ca, only two thirds (Ce: half) of the A position are occupied in the crystal. Samples with A = Y³⁺, La³⁺, Ce⁴⁺, Pr³⁺, Nd³⁺, Sm³⁺ to Yb³⁺ were prepared by solid state reaction of the binary oxides. X-ray diffraction in combination with Rietveld analysis was used to investigate the structure. The measured dielectric properties show the CDC behaviour of this material. In addition the band gap energy was determined by UV-Vis spectroscopy. Measurements of the magnetic susceptibility were carried out to study the magnetic behaviour.