Fabrication of BaZr1-XYxO3 Powder by Freeze Drying Method

Abstract

BaZr1-xYxO3 is an attractive electrolyte material for low operating temperature SOFCs and SOECs because of its high proton conductivity at temperature less than 600 oC and good chemical stability under CO2 and steam atmospheres. However, its high synthetic temperature more than 1100 oC and the high sintering temperature more than 1,600 oC to get a dense electrolyte membrane cause mismatch of the shrinkage behavior and reaction with other SOFC or SOEC component materials at the fabrication process. Therefore, in this paper, reducing the synthesizing temperature of BaZr1-xYxO3 powders by freeze dry method has been tried. In the freeze dry process, Ba(NO3)2, ZrO(NO3)2 nH2O, Y(NO3)3 nH2O were chosen as low materials. The hydration numbers of ZrO(NO3)2 nH2O and Y(NO3)3 nH2O were measured by using a differential thermogravimetric analyzer. These nitrates were mixed to produce solution with the molar ratio of metal ions what we desired. The solution was atomized and frozen rapidly by using liquid nitrogen to avoid segregation. The frozen solution was dried under vacuum condition at temperature of about -40 oC. After finishing sublimation, obtained frozen powder was heated and synthesized at the temperatures of 600 to1000 oC. As a result of X-ray diffraction analysis and energy dispersive X-ray spectrometry, it is clarified that BaZr1-xYxO3 can be synthesized at 800 oC which is lower more than 300 oC than conventional synthetic temperature. We are to report the possibility of reducing the sintering temperature of BaZr1-xYxO3 by using obtained powders and properties of the sintered BaZr1-xYxO3 such as the conductivity.