Coexistence of MA and MC phases in Pb(Mg1∕3Nb2∕3)0.68Ti0.32O3 single crystals

Abstract

The coexistence of MA (space group Cm) and MC (space group Pm) phases in as-grown Pb(Mg1∕3Nb2∕3)0.68Ti0.32O3 (PMNT32) single crystals is observed at room temperature under polarization microscopy. Laminar MA and MC domains normal to ⟨110⟩cub direction appear alternately in PMNT32 single crystals. In the heating run, the MA domains show a phase transition sequence of MA-MC-cubic, while the MC domains show only a phase transition of MC to cubic. In the cooling run, the phase transition sequence of cubic-MC-MA can be observed in the whole sample. It is suggested that the internal stress in the as-grown PMNT crystals is the main reason for the coexistence of the MA and MC phases.