Abstract: A new nano ceramic materialBSFT was prepared via a conventional solid state reaction technique and UV-VIS analysis of the sample was carried to study the optical properties. The band gap energy of the sample shows marked variation in their values with the increase in temperature. Tunable band gaps can be obtained by varying annealing temperatures. An exponentially varying absorption edge was observed and explained in terms of the Urbach’s tail. The refractive index was calculated and the results obtained also showed a systematic variation with temperature. The EDX measurements confirmed the composition of the sample.