Scalable, cost-efficient synthesis and properties optimization of magnetoelectric cobalt ferrite/barium titanate composites

Farnaz Safi Samghabadi,Long Chang,Mohammad Khodadadi,Dmitri Litvinov,Karen S Martirosyan

doi:10.1063/5.0036518

Farnaz Safi Samghabadi, Long Chang + Show 3 more

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https://doi.org/10.1063/5.0036518

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Abstract

Cobalt ferrite (CoFe2O4)/barium titanate (BaTiO3) particulate composites exhibiting high magnetoelectric coefficients were synthesized from low-cost commercial precursors using mechanical ball milling followed by high-temperature annealing. CoFe2O4 (20 nm–50 nm) and either cubic or tetragonal BaTiO3 nanoparticle powders were used for the synthesis. It was found that utilizing a 50 nm cubic BaTiO3 powder as a precursor results in a composite with a magnetoelectric coupling coefficient value as high as 4.3 mV/Oe cm, which is comparable to those of chemically synthesized core–shell CoFe2O4–BaTiO3 nanoparticles. The microstructure of these composites is dramatically different from the composite synthesized using 200 nm tetragonal BaTiO3 powder. CoFe2O4 grains in the composite prepared using cubic BaTiO3 powder are larger (by at least an order of magnitude) and significantly better electrically insulated from each other by the surrounding BaTiO3 matrix, which results in a high electrical resistivity material. It is hypothesized that mechanical coupling between larger CoFe2O4 grains well embedded in a BaTiO3 matrix in combination with high electrical resistivity of the material enhances the observed magnetoelectric effect.

Highlights

Magnetoelectric (ME) effect[1,2,3,4,5] has a number of promising applications in sensors, energy harvesting, magnetoelectric random access memory, antennas, drug delivery, etc.[6,7] In ME materials, the electric polarization can be controlled by varying the material’s magnetization state, and varying the electric polarization affects the material’s magnetization state
Since BaTiO3 is an insulator, higher BaTiO3 content leads to better electrical isolation of CoFe2O4 grains and the increase in pellet resistance, which, in turn, enables higher poling voltages
It was observed that magnetoelectric properties are strongly affected by the CoFe2O4–BaTiO3 composition, where the highest magnetoelectric coefficient is exhibited in samples prepared from a 20% CoFe2O4/80% BaTiO3 precursor mixture

Summary

Introduction

Magnetoelectric (ME) effect[1,2,3,4,5] has a number of promising applications in sensors, energy harvesting, magnetoelectric random access memory, antennas, drug delivery, etc.[6,7] In ME materials, the electric polarization can be controlled by varying the material’s magnetization state, and varying the electric polarization affects the material’s magnetization state. More robust ME behavior has been achieved in composites that combine mechanically coupled magnetostrictive and piezoelectric materials arranged in a matrix.[6,8] The ME effect in such composites is due to the induced stresses within the magnetostrictive or piezoelectric phases controlled by the application of external magnetic or electric fields, which transfer through the interface to the piezoelectric or magnetostrictive phases, respectively.[9]. These composites can be produced in versatile connectivity configurations/matrices with a wide choice of materials, volume fractions, and microstructures[8,10] and can exhibit several orders of magnitude stronger ME effect than single-phase ME materials

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