Characterization

Poster

Exploration of macroscopic and microscopic details in magnetoelectric composite ceramics

Muhammad Naveed-Ul-Haq, University of Duisburg-Essen, Essen, Germany
Morad Etier, University of Duisburg-Essen, Essen, Germany
Harsh Trivedi, University of Duisburg-Essen, Essen, Germany
Vladimir Shvartsman, University of Duisburg-Essen, Essen, Germany
Soma Salamon, University of Duisburg-Essen, Duisburg, Germany
Heiko Wende, University of Duisburg-Essen, Duisburg, Germany
Doru Lupascu, University of Duisburg-Essen, Essen, Germany

The magnetoelectric (ME) coupling is one of the fundamental mechanism for sensor design and multifield computer memories. In extrinsic multiferroics, the ME effect arises via interfacial strain between the piezoelectric and magnetostrictive phases. We outline here how the ME effect varies in composites synthesized via different synthesis routes, i.e. via the chemical nano-synthesis method and the spark plasma sintering (SPS) method. Bulk polycrystalline composites based on combinations of ferroelectric BaTiO₃ and various ferrimagnetic ferrites (viz. BaFe₁₂O₁₉, SrFe₁₂O₁₉, CoFe₂O₄, and NiFe₂O₄) were studied.

The mechanical, electrical, and magnetic properties were analyzed using techniques that include X-ray diffraction (XRD), scanning electron microscopy (SEM), piezoforce response microscopy (PFM), magneto-force response microscopy (MFM), and the superconducting quantum interference device (SQUID).

It is shown that conventionally sintered BaTiO₃-CoFe₂O₄ samples showed stronger ME effect as compared to SPS samples. Moreover, the direct and the converse ME effects were locally studied using in-situ MFM and PFM, respectively. The microscopic measurements, in conjunction with confocal Raman spectroscopy, were used to estimate the role of stress between the piezoelectric and magnetostrictive phases. The outcomes, on the whole, suggest a greater role of microstructure, as compared to that of the constituent material characteristics, in determining the persistence of the stress and hence the magnetoelectric effect within the composite. Implications on the thermodynamics of coupled problems will be discussed.

We gratefully acknowledge project funding from DFG Research Unit 1509 Ferroic Functional Materials (Lu729/12 and We2623/13).

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