Humidity sensing properties of (Na0.5Bi0.5)0.94Ba0.06 TiO3 lead-free ferroelectrics ceramics

Abstract

In this study, the humidity detection properties of the ceramic with composition (Na0.5Bi0.5)0.94Ba0.06TiO3, noted (NBT-06BT), were investigated. The NBT-06BT ceramic was synthesized by the semi-solid method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The NBT-BT ceramic material sintered at 1100 °C, crystallizes in the tetragonal system without any secondary phase and presents a heterogeneous distribution of polyhedral shaped grains with open intergranular porosities. The electrical and dielectric properties investigations show that the NBT-06BT ceramic material exhibits excellent humidity detection characteristics such as high sensitivity, good linearity and narrow hysteresis. The impedance decreases by three orders of magnitude when the relative humidity increases from 15 % to 90 % at 100 Hz. The maximum hysteresis value of the sensor is 4.69 % RH. The response time and the recovery time are about 68 s and 125 s respectively. Moreover, the sensing mechanism has been discussed in detail by analyzing the complex impedance spectra. These results indicate the potential application of the ceramic material NBT-06BT as a humidity sensor.

Keywords

• humidity sensor
• lead-free ceramics
• properties
• complex impedance plots
• semi-solid synthesis