Multiferroic composites consisting of 62 mol% ferroelectric Ba_0.97Sr_0.03TiO₃ and 38 mol% ferrimagnetic Co_1–x Ni_x Fe₂O₄ with Ni substitution levels of x  = 0, 0.25, 0.50, 0.75, and 1.00 are obtained from eutectic crystallization in a floating zone furnace. Scanning electron microscopy reveals the self‐organized formation of a 3–3 network. Epitaxy of the two phases is confirmed by single‐crystal X‐ray diffraction. All samples, except the one containing pure NiFe₂O₄, are free of impurity phases. The influence of the substitution level x on the unit cell parameters of both materials is investigated by Rietveld refinement before and after a reoxidation process in flowing oxygen at 1173 K. The amount of oxide defects is determined by thermal analysis, showing a nearly constant value throughout the whole Co_1–x Ni_x Fe₂O₄ series. The effect of Ni substitution on the magnetic properties (saturation magnetization and magnetic transition temperature) of the eutectics is investigated. The magnetoelectric (ME) properties of the samples are studied in dependence on the DC field (H _DC), the frequency of the AC field (H _AC), and temperature. The Ni content has a strong influence on the absolute value of the ME coefficient (α _ME), but only a slight effect on the general behavior of the ME properties.

中文翻译：

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共晶结晶获得具有1-3连接性的Co1-xNixFe2O4 / BaTiO3异质结构的磁电性能

由低共熔合金获得由62 mol％的铁电体Ba _0.97 Sr _0.03 TiO ₃和38 mol％的铁磁Co _{1– x} Ni _x Fe ₂ O ₄组成的多铁复合材料，其中Ni的取代水平为x  = 0、0.25、0.50、0.75和1.00。在浮区炉中结晶。扫描电子显微镜显示3–3网络的自组织形成。通过单晶X射线衍射可以确定两相的外延。除含有纯NiFe ₂ O _4的样品外，所有样品均不含杂质相。替代水平x的影响在1173 K的流动氧气中，在再氧化过程之前和之后，通过Rietveld精炼研究了两种材料的晶胞参数。通过热分析确定氧化物缺陷的量，在整个Co _{1- x} Ni中显示出几乎恒定的值_x Fe ₂ O ₄系列。研究了镍替代对共晶的磁性能（饱和磁化强度和磁转变温度）的影响。根据直流磁场（H _DC），交流磁场的频率（H _AC）研究样品的磁电（ME）特性）和温度。Ni含量对ME系数的绝对值有很强的影响（α _ME），但仅在ME属性的一般行为的轻微效果。