Over the last years there has been an enormous effort in developing lead-free ferroelectric ceramics in order to obtain good dielectric, ferroelectric, piezoelectric and pyroelectric properties than those the conventional ferroelectric ceramics based on lead, such as lead zirconate titanate. An important group of lead free ferroelectric materials belong to the Aurivillius family, compounds which are layered bismuth Sr . Ba . Bi Nb O shows better ferroelectric and pyroelectric properties.