Scalable, cost-efficient synthesis and properties optimization of magnetoelectric cobalt ferrite/barium titanate composites
Scalable, cost-efficient synthesis and properties optimization of magnetoelectric cobalt ferrite/barium titanate composites
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DOI：
10.1063/5.0036518
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发表时间：
2021-02
期刊：
影响因子：
6.1
通讯作者：
Farnaz Safi Samghabadi;Long Chang;M. Khodadadi;K. Martirosyan;D. Litvinov
中科院分区：
文献类型：
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作者：
Farnaz Safi Samghabadi;Long Chang;M. Khodadadi;K. Martirosyan;D. Litvinov
采用机械球磨和高温退火，由低成本商业前驱体合成了具有高磁电系数的钴铁氧体（CoFe2O4）/钛酸钡（BaTiO3）颗粒复合材料。 CoFe2O4 (20 nm–50 nm) 和立方或四方 BaTiO3 纳米粒子粉末用于合成。研究发现，利用 50 nm 立方 BaTiO3 粉末作为前驱体，可以得到磁电耦合系数高达 4.3 mV/Oe cm 的复合材料，与化学合成的核壳 CoFe2O4-BaTiO3 纳米粒子相当。这些复合材料的微观结构与使用 200 nm 四方 BaTiO3 粉末合成的复合材料显着不同。使用立方 BaTiO3 粉末制备的复合材料中的 CoFe2O4 颗粒更大（至少一个数量级），并且通过周围的 BaTiO3 基体彼此之间的电绝缘性明显更好，从而形成高电阻率材料。据推测，良好嵌入 BaTiO3 基体中的较大 CoFe2O4 颗粒之间的机械耦合与材料的高电阻率相结合，增强了观察到的磁电效应。
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.