The effective magnetoelectric coefficients of polycrystalline multiferroic composites
The effective magnetoelectric coefficients of polycrystalline multiferroic composites
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DOI：
10.1016/j.actamat.2005.05.014
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发表时间：
2005-09
期刊：
影响因子：
9.4
通讯作者：
Shashidhar Srinivas;Jiangyu Li
中科院分区：
文献类型：
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作者：
Shashidhar Srinivas;Jiangyu Li
在本文中，我们开发了一个自洽的方法，使用有效介质近似计算的宏观磁电（ME）系数的多晶多铁性复合材料，强调的影响，形状，体积分数，和取向分布的两相颗粒。这种方法特别适用于各相体积分数接近50%的复合材料，其中可能不存在基体相，因此平均场Mori-Tanaka模型不适用。从数值计算中观察到，对齐的粒子导致最高的ME系数和耦合因子，而随机取向的粒子导致基本上为零的ME耦合，即使ME系数是一个偶数秩张量属性。此外，据观察，层状颗粒是最佳的ME系数a11，而纤维状颗粒是最佳的a33。我们还假设，以前报道的多铁性复合材料的ME系数的理论计算和实验测量之间的巨大差异部分是由于很少被考虑的颗粒的取向分布。当我们的计算考虑到两个阶段的粒子的取向分布，与实验数据的良好协议。
In this paper, we develop a self-consistent approach using effective medium approximation to calculate the macroscopic magnetoelectric (ME) coefficients of polycrystalline multiferroic composites, emphasizing the effects of shape, volume fraction, and orientation distribution of particles of both phases. This approach is especially suitable for composites with volume fractions of each phase close to 50%, in which there may not be a matrix phase present and thus mean field Mori–Tanaka model is not applicable. It is observed from the numerical calculations that the aligned particles result in highest ME coefficients and coupling factors, while randomly oriented particles lead to essentially zero ME coupling, even though the ME coefficient is an even rank tensorial property. In addition, it is observed that lamellar particles are optimal for ME coefficient a11, while fibrous particles are optimal for a33. We also postulate that the large discrepancy between theoretical calculations and experimental measurements for ME coefficients of multiferroic composites previously reported is partly due to the orientation distribution of particles that has rarely been considered. When our calculations took the orientation distribution of particles of both phases into account, good agreement with experimental data is observed.