Study of structural, thermal and ionic conductivity of (1-x)Bi2O3.xTiO2 (0.05≤x≤0.20) systems

Abstract

Solid electrolytes are very important and essential part of solid oxide fuel cells. The Y2O3 stabilized ZrO2 (YSZ) are being used as a electrolyte in SOFCs. However, the ionic conductivity of YSZ drastically decreases below 1000 ºC. In all over the world, the efforts are being made to reduce the working temperature of SOFC for making them commercially viable. Therefore, in the present study, titanium-substituted compounds (Bi2-xTixO3+x/2 0.05≤x≤0.20) were prepared by solid-state reaction technique for its use as an electrolyte in SOFC. Structural and conductivity behavior was studied as a function of the Ti4+ substitution on bismuth site. The as prepared samples were studied by using alternating current conductivity, differential thermal analysis, SEM and X-ray diffraction techniques. The XRD results indicate the formation of Cubic Bi12TiO20 phase. Apart from this, Bi2O3 are also identified as minority phase in all the samples. The volume fraction of Bi12TiO20 phase increses with increasing concentration of TiO2 with decreasing minority phase Bi2O3. The highest ionic conductivity was observed in x=0.15 sample. The results are discussed in light of disordering and lower polarizability of Ti4+ cation as compared to Bi3+ cation.