Structure and physical properties of V 2O 5 gels containing GeO 2

Abstract

Monolithic gels of V 2O 5 containing up to 9.5 mol% GeO 2 were obtained by the hydrolysis of VO(C 2H 5O) 3 and Ge(C 2H 5O) 4 in ethanol solution. The gels were fiber-like, less than 10 nm in thickness, and became shorter with addition of GeO 2. Fracture surfaces of the xerogels containing GeO 2, 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 GeO 2 content. The bulk xerogels were electrically isotropic, and the dc conductivity decreased with increasing GeO 2 content. The refractive indices measured by ellipsometry also decreased with increasing GeO 2 content.