  Structural phase transformations of [110] electric field cooled
Pb(Mg1/3Nb2/3)O3-30%PbTiO3 (PMN-30%PT) crystals have been performed by x-ray
diffraction in a field-cooled (FC) condition. A phase sequence of
cubic(C)-tetragonal(T)-orthorhombic (O)-monoclinic (MB) was found on
field-cooling (FC); and a R-MB-O one was observed with increasing field
beginning from the zero field-cooled (ZFC) condition at room temperature. The
application of the [110] electric field induced a dramatic change in the phase
sequence in the FC condition, compared to the corresponding data for PMN-30%PT
crystals in a [001] field, which shows that the phase sequence in the FC
condition is altered by the crystallographic direction along which a modest
electric field (E) is applied. Only when E is applied along [110] are
intermediate O and MB phases observed.
