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Novel magnetoelectric composites of cobalt iron alloy and barium titanate
Author(s) -
Walther Till,
Köferstein Roberto,
Ebbinghaus Stefan G.
Publication year - 2017
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14744
Subject(s) - materials science , ferroelectricity , barium titanate , alloy , cobalt , dielectric , composite material , percolation threshold , ceramic , analytical chemistry (journal) , metallurgy , electrical resistivity and conductivity , chemistry , optoelectronics , chromatography , engineering , electrical engineering
Magnetoelectric barium titanate ceramics with embedded cobalt iron alloy particles (Co 1/3 Fe 2/3 ) x –(BaTiO 3 ) (1− x ) , with x =0.2, 0.4, and 0.6, were prepared by a polyol‐mediated synthesis with subsequent sintering in a reducing forming gas atmosphere. The samples were characterized by XRD and SEM / EDX measurements. The sizes of the Co 1/3 Fe 2/3 grains increase with x . Impedance spectroscopy showed a behavior similar to pure BaTiO 3 , in particular the occurrence of the ferroelectric‐paraelectric phase transition, and high permittivities for the sample with x =0.6, that is, near the percolation threshold. The samples exhibit soft ferromagnetic properties with large saturation magnetizations of 2.5 μ B /atom and narrow hystereses. Detailed magnetoelectric investigations revealed a unique DC ‐field dependence of α ME for all three compositions. Most remarkably, the sample with x =0.4 possesses a broad ME hysteresis and an inversion of the sign of α ME at 5 kO e.