Cold neutron scattering study on diffuse and phonon excitations in the relaxor PbMg(1/3)Nb(2/3)O3

TL;DR

This study uses cold neutron scattering to investigate diffuse scattering and phonon behavior in the relaxor ferroelectric PbMg(1/3)Nb(2/3)O3, revealing temperature-dependent features and phonon broadening.

Contribution

It provides new insights into the temperature dependence of diffuse scattering and phonon dynamics in PbMg(1/3)Nb(2/3)O3, highlighting the coexistence of different diffuse scattering sources.

Findings

Diffuse scattering persists below 600 K, indicating chemical short-range order.

Diffuse scattering coexists with polar nanoregions at low temperatures.

TA phonons broaden significantly around specific wave vectors.

Abstract

Cold neutron scattering experiments have been performed to explore the energy, temperature, and wave-vector dependence of the diffuse scattering and the transverse acoustic (TA) phonons in the relaxor PbMg(1/3)Nb(2/3)O3. We have observed a weak, but definitive, diffuse scattering cross section above the Burns temperature T_d ~ 600 K. This cross section, which is most likely caused by chemical short-range order, persists down to 100 K, and coexists with the much stronger diffuse scattering that is attributed to the polar nanoregions. A systematic study of the TA phonon around (1, 1, 0) has also been carried out. The phonon is well defined for small wave vectors q, but broadens markedly around q = (0.1, -0.1, 0).