Size Effect on Properties of Varistors Made From Zinc Oxide Nanoparticles Through Low Temperature Spark Plasma Sintering

Abstract

Conditions for the elaboration of nanostructured varistors by spark plasma sintering (SPS) are investigated, using 8‐nm zinc oxide nanoparticles synthesized following an organometallic approach. A binary system constituted of zinc oxide and bismuth oxide nanoparticles is used for this purpose. It is synthesized at room temperature in an organic solution through the hydrolysis of dicyclohexylzinc and bismuth acetate precursors. Sintering of this material is performed by SPS at various temperatures and dwell times. The determination of the microstructure and the chemical composition of the as‐prepared ceramics are based on scanning electron microscopy and X‐ray diffraction analysis. The nonlinear electrical characteristics are evidenced by current–voltage measurements. The breakdown voltage of these nanostructured varistors strongly depends on grain sizes. The results show that nanostructured varistors are obtained by SPS at sintering temperatures ranging from 550 to 600 °C.

Sintering of surfactant modified ZnO–Bi2O3 based varistor nanopowders

“…Though nanoparticles are known to densify at low temperatures, the high surface area of nanoparticles and the presence of multiple varistor forming additives and dopants [Bi 2 O 3 , Cr 2 O 3 , MnO 2 , BaO, TiO 2 , PbO, and SiO 2 ] increases the tendency of spontaneous grain growth, even at 1000 8C [12,13]. Laser sintering, spark plasma sintering and hot pressing have been attempted to arrest the grain growth during densification [14,15]. However, the high initial investments required limit their application in industries.…”

Combustion synthesis of doped nanocrystalline ZnO powders for varistors applications

“…Another important factor to achieve high performance varistor is to have the dopants distribution homogeneously throughout the grain boundary. 8,9 The only way to achieve these high performance varistors is to start with fine powders such as nanopowders as the starting materials so that fine grains and homogeneous dopants distribution are retained even after sintering. High energy milling, the technique previously used for making fine ZnO and dopants powders is cost intensive.…”

Advances in the synthesis of ZnO nanomaterials for varistor devices

“…[135][136][137][138] For example Macary et al, 137 employed the SPS technique to sinter ZnOBi 2 O 3 nanomaterial (10 nm) at temperatures ranging from 550 to 600…”