The influence of the method of addition of Al2O3 to 3YSZ material on its thermal and electrical properties

Abstract

The properties of tetragonal yttria-stabilized zirconia composites with the small addition of alumina (Al2O3-Y2O3-ZrO2 composite) obtained on two ways of synthesis were studied in terms of usability for anode materials in solid oxide fuel cell. Both methods were based on citric synthesis: in the first one, Al2O3 was coprecipitated with the tetragonal ZrO2 in the form of citrate by citric acid, while in the second Al2O3 was impregnated in the form of aluminium nitrate precursor on tetragonal ZrO2 matrix. The obtained materials were analysed by X-ray diffraction, dilatometry and impedance spectroscopy. The results of measurements show that regardless of synthesis method, the addition of Al2O3 influences the conductivity of samples by increasing their grain boundaries conductivity as an effect of removing of SiO2 and decreasing of conductivity activation energy. The impregnation of Al2O3 on tetragonal ZrO2 and sintering of this material above shrinking temperature cause, however, radical decrease of porosity of materials, which disqualifies these samples as anode materials. In the case of samples obtained by coprecipitation the significant decrease of porosity is not observed.