Domain structure of adaptive orthorhombic phase in [110]-poled Pb(Mg1/3Nb2/3)O3-30.5%PbTiO3 single crystal

The domain structure of orthorhombic phase in [110]-poled Pb(Mg1/3Nb2/3)O-3-30.5%PbTiO3 has been studied with analytical transmission electron microscopy. Convergent beam electron diffraction analysis indicates that the orthorhombic phase is an adaptive phase composed of tetragonal nanodomains while in the macroscopic scale it appear as orthorhombic due to an average effect. When poled along [110] direction, the volume ratio of the nanodomains with [100] polarization becomes equal to that of the nanodomains with [010] polarization. The nanodomain walls seem pinned, which may be a reason of the lower piezoelectric properties of orthorhombic phase.