The properties of the non-stoichiometric ceramics (1−x)PbMg1/3Nb2/3O3–(x)PbTiO3

(1−x)PbMg1/3Nb2/3O3–(x)PbTiO3 i.e. (1−x)PMN–(x)PT ceramics with x⩽0.15 have been obtained and investigated. With increasing x the temperature Tm increases, at which dielectric permittivity reaches its maximum (εm), increases the value of εm and decreases the degree of the diffuse phase transition. For x⩽0.075 dominates electrostrictive mechanism while for x>0.075 piezoelectric effect gives a contribution into electromechanical deformation of the samples. Special attention is paid to the problem of nonstoichiometry (excess and deficit of PbO and excess of MgO).