Taguchi‐optimized spark plasma‐sintered nanostructured ZnO varistors with exceptional nonlinearity and energy‐absorption performance

This study presents a comprehensive investigation of advanced nanostructured ZnO-based varistors fabricated through Spark Plasma Sintering (SPS) and optimized via the Taguchi method. An L 27 orthogonal array design was employed to systematically optimize a multicomponent ZnO system, considering both compositional variables and processing parameters. The samples were densified via SPS under precisely controlled conditions (temperature: 850–950°C, pressure: 45-55 MPa, heating rate: 100-200°C/min, holding time: 5–15 min). Microstructural analysis revealed a homogeneous nanostructure with controlled grain sizes (0.4–1.5 μm) and well-engineered grain boundaries containing localized additives. The optimized varistors achieved nonlinearity coefficients > 75 and ultralow leakage currents (< 5 μA/cm 2 ). ultralow leakage currents (<5 μA/cm 2 at 0.75V b ), and superior energy-absorption capacities (>350 J/cm 3 ). Advanced thermionic emission-diffusion modeling incorporating quantum tunneling effects accurately predicted the electrical response across all voltage regimes. Time-resolved surge testing confirmed exceptional transient response with recovery times under 50 ns. These results represent a significant advancement in varistor technology, providing next-generation surge protection solutions for power electronics and smart grid applications.