**2. Perovskite ferroelectrics**

It is a family of a subgroup of corner sharing oxygen octahedral material's exhibiting ABO3 structure. This family contains some mostly used piezoelectric and ferroelectric ceramics. Some member which is used in different field of Technology are strontium titanate (STO), barium titanate (BaTiO3), (SrTiO3), lead titanate (PbTiO3), barium strontium titanate (BST), PZT, potassium niobate (KN) (KNbO3) etc. Some of these perovskite are discussed in detail as follows.
