Abstract

In this article, we present the results of low-temperature dielectric, magnetic and magnetodielectric properties of BiFeO₃ nanoceramics prepared by auto-combustion method. Rietveld refinement results of X-ray diffraction data show that sample crystallizes in single-phase rhombohedral perovskite structure with R3c (No. 161) space group. The average crystallite size was found to be ≈ 600 Å from Williamson–Hall analysis. The temperature-dependent dielectric data have been presented in permittivity and modulus formalism to understand the relaxation dynamics. Three non-Debye-type relaxation processes were observed in the experimental window (173 to 423 K), which are explained using Kohlrausch–Williams–Watts (KWW) decay function. The temperature variation of relaxation times obeys Arrhenius's behaviour. The anomaly observed in the temperature dependence of relaxation times data near 240 K corresponds to the magnetic transition of BiFeO₃. We found that single ionized oxygen vacancies with activation energy ranging from 0.4 to 0.8 eV are involved in the relaxation process. A crossover from AFM/PM to weak ferromagnetic ordering is observed at low temperature. The variation of capacitance with an applied magnetic field shows a hysteresis effect. The magnetocapacitance (MC%) changes by 3% at a magnetic field of 2 T for 200 kHz, indicating an intrinsic bulk magnetocapacitance effect in the ceramics. Hence, the above findings highlight the significance of the material as a potential candidate for device applications.

中文翻译：

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BiFeO3多铁陶瓷的低温介电和磁性能

摘要

在本文中，我们介绍了自燃烧法制备的BiFeO ₃纳米陶瓷的低温介电、磁性和磁介电性能的结果。X射线衍射数据的Rietveld精修结果表明，样品结晶为具有R3c（No.161）空间群的单相菱面体钙钛矿结构。根据 Williamson-Hall 分析发现，平均微晶尺寸约为 600 Å。与温度相关的介电数据以介电常数和模量形式呈现，以了解弛豫动力学。在实验窗口（173 至 423 K）中观察到三个非德拜型弛豫过程，这可以使用 Kohlrausch-Williams-Watts (KWW) 衰变函数进行解释。弛豫时间的温度变化遵循阿伦尼乌斯行为。在 240 K 附近弛豫时间数据的温度依赖性中观察到的异常对应于 BiFeO ₃的磁转变。我们发现活化能范围为 0.4 至 0.8 eV 的单个电离氧空位参与弛豫过程。在低温下观察到从 AFM/PM 到弱铁磁有序的交叉。电容随施加磁场的变化表现出磁滞效应。在 200 kHz、2 T 的磁场下，磁电容 (MC%) 变化 3%，表明陶瓷中存在固有的体磁电容效应。因此，上述发现凸显了该材料作为设备应用的潜在候选者的重要性。