Characterization of Humidity Sensor Based on Nanostructured Porous LNTO Ceramics

Abstract

The present paper reports on the room-temperature characteristics of the impedance-type humidity sensor based on nanostructured porous lithium-niobium-titanium-oxide (LNTO) ceramics modified with 2 wt% of ZnO as functional additive. These ceramics were prepared by using a solid–state reaction method and final cylindrical pellet samples were sintered at 900°C for 4 h. Using scanning electron microscopy and X-ray diffraction techniques, structural analysis confirmed the desired porous nature of the synthesized LNTO ceramics with an average crystallite size in the nano range. Within a wide relative humidity range from 15% to 85%, the LNTO-based ceramic sensor exhibits a linear response with an impedance change of about two orders of magnitude at the optimal operating frequency of 15 kHz. Furthermore, fast response (17 s) and recovery (28 s), relatively small hysteresis (3.5%), repeatability and good long-term stability were also obtained.