Manoj... UV/Vis is a simple spectral technique to deal with the absorption of light by materials in solution. I mostly depend on the absorption of light at specific wavelengths due to the presence of electrons within the molecule or the ion that can be exited by radiant energy. XRD is a method for the identification of solid crystalline materials when the radiation of much lower wavelengths than UV, i., e., higher energy with the planes of a crystal. The instrumentation of XRD is more expensive than UV instrumentation... Regards