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.

Local twin domains and tip-voltage-induced domain switching of monoclinicMCphase inPb(Mg1/3Yang1, Luo2, Sun3 et al. 2016Phys. Rev. B163140View full textAdd to dashboardCite

“…For PMN-xPT single crystals, the existence of M A , M B and M C phases have been confirmed [11][12][13][14], and the phase diagram near the MPB was proposed with defined composition range of the M phase [15,16]. The M phase is believed to be closely linked with the enhanced electromechanical performance [17][18][19][20].…”

Electric-field-induced dielectric and temperature changes in a⟨011⟩-orientedPb(Mg1Peräntie1, Hagberg2, Uusimäki3 et al. 2010Phys. Rev. B1279800View full textAdd to dashboardCite

“…[20][21][22][23][24][25] Additionally, the coexistence of two or more phases as well as coexisting polar nanodomains and microdomains have been evidenced, especially in unpoled crystal states of PMN-PT. [26][27][28][29] The poling process usually removes any phase coexistences, and leaves a domain-engineered single phase structure. 17 The poling treatment required for enhanced piezoelectricity is commonly referred to as domain engineering in which a sufficiently large electric field applied in the nonpolar direction creates a set of domains where polarizations are oriented so that their angles to the poling direction are minimized.…”

Characteristics of electric-field-induced polarization rotation in 〈001〉-poled Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals close to the morphotropic phase boundary

“…However, it should be kept in mind that PMN-PT very likely has some phase coexistence as a function of temperature and field close to the MPB region, as observed in many studies. 15,16,22,[34][35][36] From this point of view, it is possible that separate regions of the crystal show different phase transitions of type M A $ T and M C $ T, where coexistence of M A and M C phases would occur and no transition between monoclinic phases would take place. Actually, coexistence of M A and M C phases has been observed by PLM in an as-grown PMN-32PT crystal, but at the same time, it was discovered that a transition between monoclinic phases, namely M A $ M C , takes place on heating and cooling, and only the M A phase was stable after cooling.…”