Condensation of the atomic relaxation vibrations in lead-magnesium-niobate at T=T*

Abstract

We present neutron diffraction, dielectric permittivity, and photoconductivity measurements, evidencing that lead-magnesium niobate experiences a diffuse phase transformation between the spherical glass and quadrupole glass phases, in the temperature interval between 400 K and 500 K, with the quadrupole phase possessing extremely high magnitudes of dielectric permittivity. Our analysis shows that the integral diffuse scattering intensity may serve as an order parameter for this transformation. Our experimental dielectric permittivity data support this choice. These data are important for the applications desiring giant dielectric responses in a wide temperature intervals and not related to electron's excitations.

Finite-temperature properties of the relaxorPbMg1/3Nb2/3O3from atomistic simulations

“…This indicates that properties of PMN are rather sensitive to the atomic configuration. Moreover, T 0 , which usually corresponds to the Curie temperature in normal ferroelectrics, can be identified here as the so-called T * temperature inherent to relaxors [5,8,[50][51][52][53]. We will come back to these points later on.…”

Relaxor Ferroelectrics: Back to the Single-Soft-Mode Picture

“…Its structure remains cubic in average down to the lowest temperatures [14]. It has been proposed that the formation of dynamical PNRs occurs around the Burns temperature T d ≃ 620 K [27,28], that they start to become static around T Ã ≃ 400-500 K [29][30][31][32][33], and that their dynamics slows down until T f ∼ 220 K [7,34] (see Fig. 1).…”

Effects of atomic short-range order on properties of the PbMg1/3Nb2/3O3 relaxor ferroelectric

“…One of these characteristics temperatures is the famous Burns temperature [3], at which it is commonly believed that relaxor ferroelectrics begin to acquire polar nanoregions that are responsible for their anomalous properties. Another temperature is often denoted as T * and is associated with an anomaly in acoustic emission and in the temperature dependence of the lattice constant, and with striking features in the Raman and neutron scatterings [4][5][6][7][8][9]. A third characteristic temperature is the depolarizing temperature, at which the poled relaxor system looses its polarization on heating [10][11][12][13].…”