Fabrication of YSZ ceramic thin films with sol-gel method for mixed potential-type zirconia-based NO2 sensor

Abstract

In this work, yttria-stabilized zirconia (YSZ) thin films were prepared by sol-gel and spin-coating methods, which are simple and inexpensive, with good film quality and excellent electrical conductivity. Using this film, a YSZ film mixed-potential type NO2 gas sensor with NiO as the sensitive electrode material was fabricated. The films had the best dielectric properties when spin-coated four times, and the sensors had the highest response (48 mV–100 ppm NO2) as well as the best sensitivity (14.8 mV/decade for 5–20 ppm NO2 and 42 mV/decade for 20–500 ppm NO2). The YSZ thin-film gas sensor operates at a lower temperature, with an optimum operating temperature of 550 °C, and the power consumption of the sensor has been reduced by approximately 46 % or more compared to conventional bulk YSZ NO2 gas sensors. This provides a very effective direction for the low-power design of high-temperature devices such as the YSZ gas sensor. In addition, thin-film devices are more conducive to integrating sensors into microelectronic circuits, greatly improving the application scenarios for such devices. This sensor has excellent repeatability, very good selectivity, and outstanding long-term stability over 30 days of continuous measurement. In conclusion, based on the excellent sensing performance and low power consumption of the YSZ thin-film gas sensor, the sensor has a promising future for in-situ monitoring of NOx.