Stable optical and structural properties are important for most of the applications of thin films. The effect of time and concentration of the sol on the optical and structural properties of the films have been investigated by evaluating the variation of transmission and reflection over a period of 175 days. Transmittance and reflectance data were obtained from a spectrophotometer and a software program was used to analyze the data and extract optical constants. Structural features were studied by an x-ray diffractometer and an atomic force microscope. Glow discharge optical emission spectroscopic depth analysis was used to look at the composition of the films. Optical and structural properties of the films prepared from the less concentrated solution changed during the aging period of 28 days due to Na diffusion from the substrate.