In the field of humidity sensors, a major challenge is how to improve the sensing performance of existing materials. Based on our previous work on Na0.5Bi0.5TiO3, a facile strategy of tuning the Bi content in the material was proposed to improve its sensing performance. Na0.5BixTiO3 (x = 0.3, 0.35, 0.4, 0.45) nanocomposites were synthesized by a hydrothermal method. Humidity sensing properties of these nanocomposites were investigated in the relative humidity range of 11% to 95%. Our results show that, compared to the sensor based on nominally pure sample (Na0.5Bi0.5TiO3), the sensor based on Na0.5Bi0.35TiO3 exhibits boosted sensing performance of excellent linear humidity response in the humidity range of 11-75% relative humidity, lower hysteresis value, and faster response/recovery time. The improvement of the sensing performance was argued to be the reason that the proper reduction in Bi content leads to a minimum value of oxygen-vacancy concentrations, thereby weakening the chemical adsorption but enhancing the physical adsorption. These results indicate that the proper underdose of the Bi content in Na0.5Bi0.5TiO3 can greatly boost the sensing performance.
Keywords: humidity sensing; hydrothermal method; linear response; sensors.