Influence of non-stoichiometric ordering on the electrostriction coefficient of lead magnesium niobate lead titanate compositions close to the morphotropic phase boundary

The effect of non-stoichiometric ordering on the electrostriction of Pb(Mg- 1/3Nb(2)/3)O-3-PbTiO3 (PMN-PT) compositions (65/35) close to morphotropic p hase boundary (MPB) has been studied using electrically induced strain and polarization methods. La was substituted (1 to 10 at %) on the A-site to co ntrol the degree of B-site cation ordering. The charge imbalance due to La3 + was compensated by two different mechanisms: (1) creation of B-site vacan cies, and (2) changing the B-site cation ratio. Electrostriction coefficien t measurements revealed dependencies on the degree of non-stoichiometric or dering and the charge compensation mechanism. A high value of the electrost riction coefficient was found to be accompanied by larger electrically-indu ced strains and smaller polarizations. In addition, the temperature depende nce of the electrostriction coefficient was studied. (C) 1999 Kluwer Academ ic Publishers.