Microstructural, Impedance Spectroscopic and Potentiometric Analysis of Ta2O5 Electrochemical Thick Film pH Sensors

Abstract

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Two types of pH sensors based on Ta2O5 thick films, interdigitated conductimetric and potentiometric ones, were screen printed on an alumina substrate. Their properties were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, electrochemical impedance spectroscopy and potentiometry. The impedance spectroscopic studies of the fabricated thick film sensors were carried out in the frequency range of 10Hz-2MHz in test solutions of pH3-12. The conductance, capacitance and impedance of the fabricated conductimetric Ta2O5 sensor were found to be distinctly pH-dependent at low frequencies. For potentiometric sensors, a sub-Nernstian behavior was obtained.