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

TL;DR

This paper investigates the diffuse phase transformation in lead-magnesium niobate using neutron diffraction, dielectric permittivity, and photoconductivity measurements, revealing a high-permittivity quadrupole phase between 400 K and 500 K.

Contribution

It identifies the integral diffuse scattering intensity as an order parameter for the phase transformation in lead-magnesium niobate.

Findings

Diffuse phase transformation occurs between 400 K and 500 K.

Quadrupole phase exhibits extremely high dielectric permittivity.

Diffuse scattering intensity correlates with the phase transition.

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 aplications desiring giant dielectric responses, in a wide temperature intervals and not related to electron's excitations.