Detection of Different Interfaces in Percolated Networks of Antimony Tin Oxide: Borosilicate Glass Composites by Impedance Spectroscopy

Abstract

Glass composites containing percolated segregated networks of conducting antimony tin oxide (ATO) nanoparticles were fabricated through the use of a hot‐pressing technique, which resulted in glass microspheres deforming into faceted polyhedra with the ATO located at the edges. Once the ATO percolated, it was shown that minor changes in the processing parameters could cause drastic differences in the electrical properties (as much as 4–5 orders of magnitude in some cases). This study aims to investigate how the hot‐pressing processing conditions, that is, temperature and pressure, can influence the electrical properties of percolated glass/ATO composites. Glass composites containing 4.8 wt% ATO, which is a concentration higher than the percolation threshold, were hot pressed at several different temperatures (550°C–675°C) and pressures (5.8–23.4 MPa) and were examined using impedance spectroscopy. A comprehensive equivalent circuit model was developed based on the microstructure of the composites and the individual impedance behavior of the materials involved. It was found that the physical arrangement as well as the individual properties of the glass, the ATO nanoparticles, and the different interfaces between ATO (point contact vs partially sintered vs glass coated) all contributed to the measured response in a quantitative way. The equivalent circuit model was successful in fitting all of the impedance behaviors at different temperature and pressures thus revealing the influence of the processing conditions on the electrical properties of percolated ATO/glass composites.