  Single crystals of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT)
poled along [001] were investigated by dielectric, x-ray, and polarized light
(PLM) and piezo-force microscopy (PFM) methods. PLM revealed {100} macro-domain
plates that formed after poling, whose size increased on heating between room
temperature and a rhombohedral \rightarrow tetragonal phase transition, above
which point a break-up of the macro-domain plates was observed. Corresponding
PFM studies demonstrated that poling reduced the size of stripe-like domains
that were internal to the macro-domain plates, whose size also increased on
heating to TR-T. The temperature dependence of both the size of the
macro-domain plates and internal sub-domains followed the Arrhenius relation
with the activation energy of 0.4-0.5eV. The coercive field displays an
abnormal increase on heating below TR-T, different than that for PMN-PT. The
anomalously increased coercive field can be ascribed to the Arrhenius-type
domain growth, indicating a simple thermally activated process and an important
role of hierarchial domains in the improved performance of PIN-PMN-PT.
