STRUCTURE AND PHYSICAL-PROPERTIES OF V2O5 GELS CONTAINING GEO2

Monolithic gels of V2O5 containing up to 9.5 mol% GeO2 were obtained by the hydrolysis of VO(C2H5O)3 and Ge(C2H5O)4 in ethanol solution. The gels were fiber-like, less than 10 nm in thickness, and became shorter with addition of GeO2. Fracture surfaces of the xerogels containing GeO2, dried at room temperature, were glassy. However, broad peaks of X-ray diffraction were observed for the gels which suggested a layer-like structure. The crystallization temperature of the xerogels increased with increasing GeO2 content. The bulk xerogels were electrically isotropic, and the dc conductivity decreased with increasing GeO2 content. The refractive indices measured by ellipsometry also decreased with increasing GeO2 content. © 1990.