Development of nanoscale polarization fluctuations in relaxor-based (1-x)Pb(Zn1/3Nb2/

Abstract

The precursor dynamics of ferroelectric phase transitions in relaxor-based ferroelectric (1 − x) Pb(Zn 1/3 Nb 2/3 )O 3 -xPbTiO 3 single crystals, with x = 0.07, 0.10, and 0.12, were investigated using inelastic light scattering from a longitudinal acoustic phonon. An acoustic anomaly in a broad temperature range, which is characteristic of relaxor ferroelectrics, was observed. We describe the anomalies in the paraelectric phase by assuming local piezoelectric coupling inside polar nanoregions, which are surrounded by a nonpolar matrix. On the basis of local piezoelectric coupling, a relaxation time τ and a dynamic characteristic length L of the order-parameter (polarization) fluctuations were determined to be in the order of 10 −13 s and 10 −9 m, respectively. The τ and L values increase sharply upon cooling from high temperatures but more gradually below the intermediate temperature T * (=493 − 510 K). This result implies that the local polarization fluctuations grow rapidly upon cooling down to above T * and the growth rate decreases below T * . The inflexion point of this growth process in the paraelectric phase is related to the characteristic properties of relaxor-based solid solutions.

Critical slowing down and elastic anomaly of uniaxial ferroelectricCa0.28Ba0.72Nb2O6crystals with tungsten bronze structure

“…Between T B ∼ 790 and T C ∼ 527 K, the polarization fluctuations of the PNRs along the ferroelectric c axis were observed as the CP, which is common in Refs. [36][37][38]. The remarkable temperature dependence of the CP upon cooling was observed as shown in Fig.…”

“…Such a divergent phenomenon of the sound attenuation reflects the dissipation of the LA mode by the interaction with dynamic PNRs [36]. Below T C , the heating and cooling processes show a noticeable difference, which is due to the metastable irreversible domain structure caused by the finite cooling rate [37,38]. As shown in Fig.…”

Ferroelectric precursor behavior of highly cation-ordered PbSc0.5Ta0.5O3 detected by acoustic emission: Tweed and polar nanoregions

“…12-21,30-35 On further cooling, a smeared frequency dependent temperature maximum of the dielectric response occurs near T m and, slightly below T m the freezing occurs at the freezing temperature T f , similar to polar-glass phases. [36][37][38][39] In contrast to these observations, one finds that AE studies [12][13][14][15][16][17][18][19]22,23,[25][26][27][28][29][30] show extremely sharp singularities at T d and T * , which is sometimes related to changes of the thermal expansion. 40 While this behavior is unlikely when the anomaly is close to the Widom line and far away from the transition point, 41 we will also show in this paper that AE persists even without any changes in thermal expansion.…”

“…[25][26][27][28][29] Similar behavior is found near the intermediate temperature T * . [12][13][14][15][16][17][18][19][20][21][30][31][32][33][34][35] On further cooling, a smeared frequency dependent temperature maximum of the dielectric response occurs near T m and, slightly below T m the freezing occurs at the freezing temperature T f , similar to polar-glass phases. [36][37][38][39] In contrast to these observations, one finds that AE studies [12][13][14][15][16][17][18][19]22,23,[25][26][27][28][29][30] show extremely sharp singularities at T d and T * , which is sometimes related to changes of the thermal expansion.…”

“…In addition, the transition between a paraelectric and a ferroelectric phase is not only smeared but also split into a number of other singularities which are commonly ascribed to the existence and temperature evolution of polar nanosized regions (PNRs), 6,7 The structural properties of PNRs are still not fully understood with few studies focused on atomic-level correlation effects between PNRs. 8 Smooth crossover near the Burns temperature T d at high temperature range is seen in RFEs by the temperature evolution of the refractive index, 9-11 dielectrics and Brillouin light scattering, [12][13][14][15][16][17][18][19] polarized Raman spectra, 20,21 thermal expansion, [22][23][24] and acoustic emission (AE). [25][26][27][28][29] Similar behavior is found near the intermediate temperature T * .…”