Polyaniline/CaTi_0.8Fe_0.2O₃ composites for humidity sensors

Łukasz Łańcucki, Paweł Pasierb

Quarterly No. 4, 2015 pages 233-242

DOI:

keywords: polyaniline, nanofiber, composite, iron doped calcium titanate, humidity sensor, conductivity

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abstract Polyaniline (PANI) is a conductive polymer material with a huge potential for constructing different electrochemical devices. Different strategies can be used to modify and optimize polymer properties from the point of certain applications, e.g. for the construction of gas sensors. Among those strategies, the formation of composite materials comprising PANI as the base material and ceramic powder material as a modifier is a promising approach. In this work the results concerning the influence of CaTi_0.8Fe_0.2O₃ (CTFO) powders on some physicochemical properties of polyaniline (PANI) were presented and discussed. The materials were obtained by the polymerization of an aniline solution where CTFO powder, prepared by the solgel method was added. The microstructures of the materials were characterized using Scanning Electron Microscopy (SEM), the structure and phase composition was tested by X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The electrical properties of the developed PANI-CTFO composites were determined using Electrochemical Impedance Spectroscopy (EIS). The gas sensing properties of the constructed sensor devices in the presence of water vapor were tested by measurements of DC electrical conductivity changes as a function of water vapor partial pressure. The current-voltage (I-U) characteristics were also used to characterize the influence of CTFO material on PANI electrical properties. It was found that the introduction of CTFO into the PANI host material leads to substantial changes in the material properties comparing to unmodified PANI. The discussion concerning the influence of the used modifiers on the structure, microstructure and electrical and sensing properties of the developed materials and observed correlation is also presented. The mechanism of the observed influence of CTFO on PANI properties is also proposed. The dominating role of the PANI-CTFO interface on the material properties is postulated.