Dielectric properties, polarization process, and charge transport in granular (FeCoZr)x(Pb(ZrTi)O3)(100−x) nanocomposites near the percolation threshold

Oleksandr Boiko,Peter Minárik,Daria Drozdenko

doi:10.1063/6.0001356

Oleksandr Boiko, Peter Minárik + Show 1 more

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https://doi.org/10.1063/6.0001356

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Abstract

This paper presents the research of dielectric properties of (FeCoZr)x(Pb(ZrTi)O3)(100−x) granular metal–dielectric nanocomposites below the percolation threshold. Tested materials have been prepared by using the ion beam sputtering technique in the atmosphere of argon and oxygen. The impedance spectroscopy method has been used to investigate the polarization processes and dielectric relaxation mechanism in the granular nanocomposites. AC measurements in the frequency region of 50 Hz to 1 MHz and measuring temperature range of 81–293 K have been performed. Interfacial, in the low frequency region, and dipolar, in intermediate and high frequency regions, types of polarization processes were observed. The interfacial relaxation process testifies to charge accumulation at the interfaces (grain boundaries) between conductive nanoparticles surrounding an insulative matrix, as well as the space charge region around the contact area between the measurement probes and tested sample. Dipolar polarization corresponds to electric dipole formation after applying to the material an external electric field. The conduction mechanism in the tested material is considered to be hopping carrier exchange and takes place between metallic phase nanograins. It corresponds to the exponential frequency dependence of conductivity. The relaxation mechanism in the (FeCoZr)x(Pb(ZrTi)O3)(100−x) layer has been estimated as a near-Debye process with relaxation time distribution. The nanocomposite exhibits dielectric type and capacitive characteristics in the whole measuring frequency range.

Highlights

Granular metal–dielectric nanocomposites (MDNCs) form a very attractive and interesting group of functional materials demonstrating non-conventional physical properties
This paper presents the research of dielectric properties of (FeCoZr)x(Pb(ZrTi)O3)(100−x) granular metal–dielectric nanocomposites below the percolation threshold
According to the impedance model of granular MDNCs presented in Ref. 30, such a behavior of φ(ω) is typical for the films below percolation threshold (x < xc)

Summary

Introduction

Granular metal–dielectric nanocomposites (MDNCs) form a very attractive and interesting group of functional materials demonstrating non-conventional physical properties. Having an amorphous grained structure,[1,2] the specific chemical composition including pure metals[3,4] or metal alloys[5,6] as fillers, and various dielectrics[7,8] as base materials, MDNCs show unusual electrical properties, such as hopping charge carriers,[9,10] voltage and current resonances,[11,12] percolation phenomena,[13] and multiple relaxation times correlated with different polarization mechanisms.[14,15]. These advantages allow MDNCs to find various applications in modern aspects of technology and science. Metal–insulator substances consisting of nanoparticles with core–shell structures have found a lot of applications in medicine and bioengineering technologies.[20,21]

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