Size effects on varistor properties made from zinc oxide nanoparticles by low temperature spark plasma sintering

International audience; 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 oxides 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 (SEM) and X-Ray Diffraction (XRD) analysis. The non linear electrical characteristics are evidenced by current-voltage (I-V) measurements. The breakdown voltage of these nanostructured varistors strongly depends on grain sizes. The results show for the first time that, nanostructured varistors are obtained by SPS at sintering temperatures ranging from 550 to 600°C.