Prior poling effect on thermal phase stability in (110)-cut Pb(Mg1/3Nb2/3)0.74Ti0.26O3 single crystal

Abstract

Phases and domains in a (110)-cut Pb(Mg1∕3Nb2∕3)0.74Ti0.26O3 (PMNT26%) single crystal have been investigated as functions of temperature and dc electric (E) field by dielectric permittivity, polarizing microscopy, and electric polarization. The unpoled sample has a dominant rhombohedral (R) phase, which coexists with monoclinic (M) phase domains, i.e., R∕M at room temperature. With 45kV∕cm dc poling applied along [110] at room temperature, a single domain of R phase with polar orientation perpendicular to the poling field, i.e., Ṟ, was obtained. After the poling was removed, the poled sample has Ṟ/M microdomains, where the M distortion is close to the R phase. The zero-field-heating domain patterns in both unpoled and poled samples exhibit continuous polarization rotation via an intrinsic M phase in the regions of 355-375 and 365-380 K, respectively. Orthohombic and tetragonal phases were not observed in the temperature-dependent study. In general, a rhombohedral/monoclinic→monoclinic→cubic transition sequence takes place upon heating for unpoled and poled samples.