The present PhD thesis deals with extensive investigation of magnetic and dielectric properties of (1) YFe1-xMnxO3 (x = 0 to 0.3), (2) Bi1-xSmxFeO3 (x = 0 to 0.3), (3) PbTi1-xFexO3 (x = 0 to 0.3) and (4) BaTi1-xFexO3 (x = ...