Phase transitions of Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 (PMN-0.34 PT) have been studied by using dielectric constant variations, polarization-electric field hysteresis loops, and polarizing light microscopy (PLM). Even without the assistance of electric field, orthorhombic (O) phase exists in the C-oriented PMN-0.34 PT single crystals during the heating process, which is confirmed by the polarizer/analyzer extinction angle from full-angle in situ PLM observation combined with the grayscale image analysis. The phase transition sequence is monoclinic (MC) → O → MC → tetragonal (T) → cubic (C), which is different from the commonly accepted MC → T → C sequence. The existence of the O phase accompanies with much enhanced dielectric and piezoelectric performance, which indicates a new mechanism to produce large piezoelectricity in PMN-PT single crystals.
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry