Single-crystal neutron diffuse scattering and Monte Carlo study of the relaxor ferroelectric PbZn_1/3Nb_2/3O₃(PZN)

Abstract

Full three‐dimensional diffuse neutron scattering data have been recorded from a single crystal of Pb(Zn1/3Nb2/3)O3 (PZN) at 300 K using the time‐of‐flight Laue technique on the SXD single‐crystal instrument at ISIS. The data show a series of diffuse rods of scattering oriented parallel to each of the six 〈1 1 0〉 crystal directions. Monte Carlo simulation has been used to demonstrate that the diffuse rods are caused by planar nanodomains oriented normal to the 〈1 1 0〉 directions. Within these domains, there are correlated displacements of the atoms away from their average site positions. In order to explain the systematic absence of some rods of scattering in the (h k 1) data but the presence of all rods in the (h k 0) data, it is necessary that the displacement of an O atom is of opposite sign to that of its neighbouring Pb atoms. This is explained in terms of a model based on the fact that Pb2+ possesses a lone pair of electrons, giving the Pb ion directionality.

Single Crystal Diffuse Neutron Scattering

“…For each run 600 exposures of 60 s were recorded at 0.2 • intervals, making a total collection time of 10 h. The sample was contained in a cryofurnace but a collimator was used to eliminate scattering from this and only allow neutrons emitted radially from the sample at the centre of the furnace to reach the detector. The data shown in Figure 5c compare well with data shown in Figure 5a that were recorded earlier on SXD (see reference [16]). These SXD data were recorded in ∼ 20 h. The sample sizes in the two different experiments were comparable (175 mm 3 versus 192 mm 3 ).…”

Neutron and x-ray diffraction study of cubic [111] field-cooledPb(Mg1∕3Nb2∕3)Stock1, Xu2, Gehring3 et al. 2007Phys. Rev. BSelf Cite593462View full textAdd to dashboardCite

“…The fact that the diffuse scattering is only diminished below T c and, in particular, very anisotropic ͑being elongated strongly along one direction͒ and exhibits no memory is suggestive that the diffuse scattering is directly related to the polar structure in the relaxor ferroelectrics as described in several models. 19,41 An important result is that our measurements show a clear structural signature of two distinct temperature scales. At a high temperature, the diffuse scattering is onset and is insensitive to the application of an electric field.…”

“…15,16 Several models describing the diffuse scattering in terms of phase-shifted polar nanoregions and static strain fields have been proposed. [17][18][19][20] We emphasize that all of these models relate the diffuse scattering to the presence of polar correlations in the material. Therefore investigating the effects of an external electric field on the diffuse scattering, direct information of the local polar correlations can be obtained.…”

Interplay between static and dynamic polar correlations in relaxorPb(Mg1/3Nb2/3Stock1, Eijck2, Fouquet3 et al. 2010Phys. Rev. BSelf Cite628681View full textAdd to dashboardCite

“…2͑a͒. [16][17][18][19][20] Despite uncertainties in the origin of the diffuse-scattering cross section, the polar nature of the diffuse scattering in the lead-based relaxors has been established through three different means. First, the onset of the diffuse scattering in PMN was shown to coincide with the temperature at which a ferroelectric-active, soft, transverse-optic mode reaches a minimum frequency ͓see Fig.…”