Engineered amorphous interfaces in cold-sintered ZnO-PAN hybrids: Synergistic thermal insulation and nonlinear electrical properties

Abstract

This study presents a method to enhance ZnO ceramics by incorporating amorphous polyacrylonitrile (PAN) grain boundaries. Using an optimized cold sintering process, we synthesized ZnO-PAN composites with relative densities exceeding 92 %. The amorphous PAN interfaces significantly improve both electrical and thermal properties. The ZnO-PAN composites show a 12.5-fold increase in threshold electric field and a 16-fold enhancement in breakdown field strength compared to pure ZnO. The composite with 3 vol% PAN exhibits a high nonlinear coefficient of 13.3, setting a benchmark for ZnO-polymer binary varistors. Additionally, the amorphous grain boundaries enhance phonon scattering, reducing thermal conductivity to 0.72 W/m·K at room temperature. These superior thermal insulation properties, coupled with good varistor performance, highlight the potential of ZnO-PAN composite as a surge protection material with integrated thermal insulation, making it ideal for advanced applications in electric vehicle circuits.