The complex impedance, complex permittivity and, alternating current (ac) conductivity investigations of the CuO/CuFe₂O₄ nanocomposites, prepared by using via co-precipitation and sol-gel methods, were performed between 1 Hz and 40 MHz within 296 K–433 K in the present study. The structural analyses of the samples were determined by scanning electron microscope (SEM), X-ray diffraction (XRD) analysis, energy dispersive X-ray (EDX) spectroscopy and X-Ray Fluorescence (XRF) techniques. The ac impedance and complex permittivity results revealed that these ferrite systems have a heterogeneous structure consisting of conducting grains surrounded with less conducting grain boundaries which are expressed by Koop’s model. Additionally, the temperature dependent dc conductivity showed up the semiconductor-conductor and conductor-semiconductor transitions in different temperatures. From this point of view, the nanocomposites exhibiting conductive or semiconductor behavior depending on temperature have the potential to be used in many electronic devices, including sensor applications. Moreover, the activation energies of the samples calculated by the Arrhenius plots of the dc conductivity indicated both electron and hole hopping processes for the conduction. Furthermore, small polaron charge transport mechanism was implied by the high activation energies. Ac conductivity analyses of the samples showed that the ferrites prepared in the present work exhibit correlated barrier hopping dominantly for the ac conduction.

Graphical Abstract

CuO / CuFe ₂ O ₄的复数阻抗，复数介电常数和交流电（ac）电导率研究在本研究中，通过共沉淀和溶胶-凝胶法制备的纳米复合材料在296 K–433 K范围内的1 Hz至40 MHz之间进行。通过扫描电子显微镜（SEM），X射线衍射（XRD）分析，能量色散X射线（EDX）光谱和X射线荧光（XRF）技术确定样品的结构。交流阻抗和复介电常数结果表明，这些铁氧体系统具有异质结构，由导电晶粒包围，导电晶粒边界较少，由Koop模型表示。另外，温度相关的直流电导率在不同温度下显示出半导体-导体和导体-半导体的转变。从这个角度来看，根据温度显示导电或半导体行为的纳米复合材料具有在包括传感器应用在内的许多电子设备中使用的潜力。此外，通过直流电导率的阿伦尼乌斯图计算出的样品的活化能表明了电子和空穴的跃迁过程。此外，高活化能暗示了小的极化子电荷传输机制。样品的交流电导率分析表明，在本工作中制备的铁氧体表现出相关的势垒跳变，这对交流电起主要作用。通过直流电导率的阿伦尼乌斯（Arrhenius）图计算出的样品的活化能表明了传导的电子和空穴跳跃过程。此外，高活化能暗示了小的极化子电荷传输机制。样品的交流电导率分析表明，在本工作中制备的铁氧体表现出相关的势垒跳变，这对交流电起主要作用。通过直流电导率的阿伦尼乌斯（Arrhenius）图计算出的样品的活化能表明了传导的电子和空穴跳跃过程。此外，高活化能暗示了小的极化子电荷传输机制。样品的交流电导率分析表明，在本工作中制备的铁氧体表现出相关的势垒跳变，这对交流电起主要作用。

图形概要