Permittivity measurements in nanostructured TiO2 gas sensors

A. GIBERTI; M. CAROTTA; C. MALAGU; C, ALDAO; M. CASTRO; R. PARRA; M. PONCE

PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2011 vol. 108 p. 118 - 122

1862-6300

Permittivity measurements in nanostructured TiO2 gas sensors  A. Giberti1, C. Malagù1, M. Carotta1 M. A. Ponce2, R. Parra2, M. S. Castro2, C. M. Aldao2.   1 University of Ferrara - Department of Physics, Via Saragat 1/c, 44100 Ferrara, Italy 2 Institute of Materials Science and Technology (INTEMA), University of Mar del Plata - National Research Council (CONICET), Juan B. Justo 4302, B7608FDQ Mar del Plata, Argentina       Abstract Resistance and capacitance measurements, as a function of frequency, were carried out to analyze and model the electrical behavior of undoped titanium dioxide (TiO2) films. The sensing measurements were carried out in a chamber with independent temperature, pressure, gas composition and flow rate control. With the aim of evaluating the electrical response of the sample as a function of the surrounding atmosphere, a frequency range of 100 Hz to 4 MHz was used (vacuum or air at atmospheric pressure). The resistance and capacitance responses were obtained with the help of impedance spectroscopy technique. The impedance response vs. frequency allows the discrimination between grain-boundary capacitance (Cgb) and resistance (Rgb) contributions. A model, taking into account the possible effects due to grain size is proposed in order to work out the permittivity of the material.