S. N. Gvasaliya, R. A. Cowley, L. I. Ivleva, S. G. Lushnikov, B. Roessli, A. Zheludev
Neutron scattering measurements have been used to study the phase transition of SBN-61 (Sr0.61Ba0.39Nb2O6) at a temperature Tc ~ 350 K. The transverse acoustic branch propagating along the [1, 1, 0] direction was measured. The results showed that this branch is not temperature dependent near the phase transition. Additional diffuse scattering, elastic within the resolution, was observed at lower energies than the transverse acoustic mode. Unexpectedly, on cooling from a temperature well above the phase transition, the intensity of the quasi-elastic scattering increased whereas the width did not change much. Below the phase transition it became very difficult to separate the Bragg reflection from the diffuse scattering. Assuming that this scattering is caused by the domain walls, it was possible to describe the data. The results show that the thickness of the domain walls steadily increases below Tc. We found no evidence that electric random-fields produce pronounced effects on the scattering properties of Sr0.61Ba0.39Nb2O6.
View original:
http://arxiv.org/abs/1206.2012
No comments:
Post a Comment