Investigation on microscopic mechanisms of high-Curie temperature PMN-PH-PT piezoelectric ceramics

Abstract High-Curie temperature (TC) piezoelectric ceramics 0.15Pb(Mg1/3Nb2/3)O3-0.38PbHfO3-0.47PbTiO3 (0.15PMN-0.38PH-0.47PT) were fabricated via the citrate method, which shows pure perovskite structure. The ceramics have composition locating at the rhombohedral side around the morphotropic phase boundary (MPB), and present enhanced electrical properties as compared with those prepared by the solid-state reaction method via the columbite precursor technique. Temperature-dependent Raman spectroscopy not only proves the occurrence of the ferroelectric to paraelectric phase transition around TC, but also detects the successive phase symmetry transitions, which correlate with the polar nanoregions (PNRs) or the coexistence of multiple ferroelectric phases. Large quantities of fine stripe nanoscale ferroelectric domains are observed by piezoresponse force microscopy (PFM) in the 0.15PMN-0.38PH-0.47PT ceramics, which form the larger micron island domains. Temperature-dependent Raman spectra and PFM results indicate that the excellent dielectric, ferroelectric and piezoelectric properties of the 0.15PMN-0.38PH-0.47PT ceramics can be attributed to either the existence of the PNRs with low symmetry or the multiple-ferroelectric-phases coexistence around room temperature and the fine stripe ferroelectric domains.