Study of the humidity-sensing mechanism of CaCu3Ti4O12

• Published in: Sensors and actuators. B, Chemical Vol. 228; pp. 443 - 447
• Main Author: Li, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 02.06.2016
• Subjects: Actuators; BOUNDARIES; CaCu3Ti4O12; Capacitance; CERAMICS; COPPER OXIDE; Electrodes; Grain boundaries; High dielectric constant; HUMIDITY; Humidity sensor; Impedance spectroscopy; Orientation; Polarization; Potential barrier capacitance; Relative humidity; Water chemistry; Humidity sensor; Potential barrier capacitance; CaCu3Ti4O12; Impedance spectroscopy; High dielectric constant
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2016.01.067

•CaCu3Ti4O12 (CCTO) is observed to respond to water vapor by changing its capacitance.•The adsorption of water molecules affects the potential barrier capacitances of CCTO.•The polarizations caused by the physisorbed water induce the increase in capacitance. CaCu3Ti4O12 (CCTO11CCTO is the abbreviation of CaCu3Ti4O12.) is observed to respond to water vapor by changing its capacitance. To investigate the underlying reason for the humidity-sensitive properties of CCTO, impedance spectroscopy and electric modulus plot measurements were performed at different relative humidities (RH22RH is the abbreviation of relative humidity.). Additionally, DC bias was applied to the measurement. The results indicate that the adsorption of water molecules affects the potential barrier capacitances at the CCTO/electrode interface and at the grain boundary, which further changes the total capacitance of CCTO. In addition, new low-frequency polarization relaxations were observed at high RH. The new polarization relaxations may be related to the orientation polarization and space charge polarization caused by the physically adsorbed water molecules. The two polarizations may account for the large increase of capacitance at high RH.