Synthesis by Hydrothermal Treatment of ZnO-Based Varistors Doped with Rare Earth Oxides and Their Characterization by Impedance Spectroscopy

J Porcayo-Calderon,J.J Ramos-Hernandez,C.D Arrieta-Gonzalez,L Martinez-Gomez,J.P Flores-De Los Rios,J.G Gonzalez-Rodriguez,E Porcayo-Palafox,M Sanchez-Carrillo,J.G Chacon-Nava

doi:10.3390/cryst10121134

J Porcayo-Calderon, J.J Ramos-Hernandez + Show 7 more

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https://doi.org/10.3390/cryst10121134

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Journal: Crystals	Publication Date: Dec 12, 2020
Citations: 5	License type: CC BY 4.0

Affiliation: Universidad Autónoma del Estado de Morelos

Abstract

ZnO-based ceramic varistors have shown excellent electrical and dielectric properties due to their characteristics microstructures represented by the arrangement of their grains and grain boundaries that allow the absorption and flow of energy when subjected to an electrical surge. Their properties and characteristics depend on their chemical compositions and processing routes. Typical processing routes involve several stages of grinding and precalcination—which are time consuming processes. Because of this, this study proposes a simpler and cheaper alternative route for processing ceramic varistors. The alternative process proposed is the mixing of the precursor oxides by means of a hydrothermal treatment. The characteristics and properties of the synthesized ceramic varistors were evaluated by means of scanning electron microscopy, X-ray diffraction and impedance spectroscopy, considering the effect of the addition of rare earth oxides (La2O3, CeO2 and Nd2O3). The results showed that the mixing of the oxides through hydrothermal treatment produces ceramic varistors with characteristics and properties similar to those obtained by other processing routes. Furthermore, it was observed that the addition of rare earth oxides affects the characteristics and properties of the ceramic varistor depending on the type of rare earth oxide added, its concentration and ionic radius.

Highlights

Due to its extraordinary electrical, dielectric and optical properties, zinc oxide (ZnO) has been used in various industrial applications, and one of the most notable applications is its use in varistor systems [1]
The varistor behavior depends on the different components added to its formulation, where Bi2 O3 is one of the main components and it is responsible for inducing non-linear behavior, while on the other hand Sb2 O3 and other oxides enhance the non-linearity of the ceramic varistor [3]
This study proposes the elaboration of ceramic varistors through the hydrothermal treatment of the precursor oxides, and their subsequent calcination

Summary

Introduction

Due to its extraordinary electrical, dielectric and optical properties, zinc oxide (ZnO) has been used in various industrial applications, and one of the most notable applications is its use in varistor systems [1]. ZnO-based ceramic varistors are used as surge protection devices in the electronics industry and as lightning conductors in power distribution systems. Ceramic varistors show non-ohmic behavior attributed to their microstructure and to the conduction processes that take place between the different. The varistor behavior depends on the different components added to its formulation, where Bi2 O3 is one of the main components and it is responsible for inducing non-linear behavior, while on the other hand Sb2 O3 and other oxides enhance the non-linearity of the ceramic varistor [3]. Ceramic varistors have a high dielectric constant due to the formation of (non-conductive grain boundary–conductive grain) pairs [4]. Grain boundaries act as potential barriers because they favor the absorption and flow of energy when subjected to an electrical surge [5]

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