Ultra‐Rapid Blacklight Sintering for ZnO‐Based Varistors With Optimized Functional Properties

ABSTRACT The increasing demand for energy‐efficient optoelectronic systems has intensified interest in high‐performance ceramic varistors, which are critical components in surge protection applications. In this study, ZnO‐based varistors were fabricated using a novel blacklight sintering (BLS) technique, which employs high‐powered blue light, and were benchmarked against conventionally sintered (CS) counterparts. The BLS method enabled ultra‐rapid heating rates (up to 40 Ks − 1 ) and achieved full densification within just 60 s—reducing the total sintering time by nearly two orders of magnitude compared to CS—while also favorably modifying the microstructure. SEM analysis revealed a fine‐grained microstructure with homogeneous grain size distribution and a low content of the unfavorable pyrochlore phase in BLS varistors. Electrical measurements showed that the BLS varistors exhibited a nonlinearity coefficient of α = 46 ± 3, which falls within the typical range for CS samples ( α = 41 ± 2). They also exhibited a markedly higher switching field of 1088±98 V/mm—more than four times that of the CS counterparts (234 ± 16 V/mm)—demonstrating the effectiveness of the blacklight sintering approach. Impedance and modulus spectroscopy confirmed the superior electrical homogeneity of BLS ceramics, making them less prone to degradation from small pathways with higher conductivity. These findings demonstrate that blacklight sintering is a promising, energy‐ and time‐efficient alternative to conventional thermal sintering for fabricating advanced electroceramic components.