Search for the X-phase in poled PZN-PT using very high-resolution single-crystal neutron diffraction

Reports that in PbZn1/3Nb2/3O3 - x% PbTiO3 ( PZN - PT) relaxor ferroelectric crystals an 'X- phase' exists, which has a cubic interior and a 10 - 50 mu m thick rhombohedrally distorted surface, have been re-examined to resolve the effect of electric poling. The crystal structure of electrically poled and de- poled PZN - 4.5% PT single crystals has been studied using a novel rotating single-crystal method on the high- resolution neutron powder diffractometer at the ISIS Facility. The recorded patterns are neutron time- of- flight analogues to the zero layer lines of rotating single- crystal x- ray diffraction patterns. Both [ 001] and [ 110] zones were examined and they demonstrate unequivocally that the crystals do not have a cubic core. There appears now to be direct evidence against the occurrence of the 'X- phase' in every circumstance in which, based on synchrotron studies, it was previously proposed to exist.