3D-Printed Polysilazane/Cr₂O₃ Composite Thick-Film Negative Temperature Coefficient Thermistors for High-Temperature Sensing Applications

Thin and thick-film sensors play a crucial role in temperature monitoring under extreme thermal conditions. However, thin/thick films based on noble metals are prone to oxidation, which compromises their stability and long-term reliability. To overcome this limitation, we fabricated thick-film negative temperature coefficient (NTC) thermistors using polysilazane (PSZ)/Chromium(III) Oxide (Cr2O3) nanoinks, achieving superior performance through the systematic optimization of the ink composition and annealing parameters. In this process, PSZ transforms into an amorphous matrix that forms a cohesive composite with Cr2O3, thereby enhancing the interfacial adhesion and lowering the sintering temperature. Such a structure underpins the remarkable thermal stability of the devices, which exhibit a resistance drift rate of only 0.5%/h at 1300 °C and remain functional after 10 h of exposure at 1500 °C with a drift rate of 9.4%/h. By extending this functional ink-based printing strategy, conformal thin-film NTC thermistors were directly printed onto curved Aluminum Oxide (Al2O3) substrates. Collectively, this work establishes a new pathway for the rapid fabrication of ultrahigh-temperature thick-film NTC thermistors.