Regensburg 2025 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 1: (Multi)ferroic States: From Fundamentals to Applications (I)

KFM 1.5: Vortrag

Montag, 17. März 2025, 10:45–11:00, H9

Stoichiometry of CoFe2O4 as a key to phase control and improved functional properties of multiferroic BaTiO3-CoFe2O4 bulk composites — •Daniil Lewin, Sofia Shamsulbahrin, Vladimir V. Shvartsman, and Doru C. Lupascu — Institute for Materials Science and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstrasse 15, 45141, Essen, Deutschland

Composite multiferroics have been widely studied as materials with a large magnetoelectric effect at room temperature. Barium titanate -- cobalt ferrite composites are among the first and most reliable composite systems of such kind. Unfortunately, high-temperature sintering can result in the formation of secondary phases and undesirable chemical modifications, particularly that of barium hexaferrite (BaFe12O19). We present a method to suppress the formation of this phase both by sintering in nitrogen and by changing the stoichiometry of cobalt ferrite to incorporate more cobalt. The latter restricts the diffusion of the iron cations into the barium titanate during sintering. Moreover, composite samples with non-stoichiometric cobalt ferrite show up to a threefold improvement in magnetoelectric coefficient when compared to samples made with stoichiometric cobalt ferrite.

Keywords: magnetoelectric; multiferroic composite; barium titanate; cobalt ferrite; barium hexaferrite