https://doi.org/10.1140/epjb/e2004-00276-8
Neutron scattering study of PbMg1/3Ta2/3O3 and BaMg1/3Ta2/3O3 complex perovskites
1
Laboratory for Neutron Scattering, ETHZ & Paul Scherrer Institut,
5232 Villigen PSI, Switzerland
2
Ioffe Physical Technical Institute,
26 Politekhnicheskaya, 194021, St. Petersburg, Russia
Corresponding author: a severian.gvasaliya@psi.ch
Received:
18
March
2004
Published online:
9
September
2004
Neutron scattering investigations were carried out in PbMg1/3Ta2/3O3
and BaMg1/3Ta2/3O3 complex perovskites. The crystal structure
of neither compound shows any phase transition in the temperature range
1.5–730 K. Whereas the temperature dependence of the lattice
parameter of BaMg1/3Ta2/3O3 follows the classical expectations,
the lattice parameter of relaxor ferroelectric PbMg1/3Ta2/3O3
exhibits anomalies. One of these anomalies is observed in the same temperature
range as the peak in the dielectric susceptibility. Below K
PbMg1/3Ta2/3O3 exhibits very small thermal expansion, similar to
invar alloys. We find that in PbMg1/3Ta2/3O3,
lead ions are displaced from the ideal positions in the perovskite structure at
all temperatures. Consequently short-range order is present. This induces strong
diffuse scattering with an anisotropic shape in wavevector space. The
temperature dependences of the diffuse neutron scattering intensity and of the
amplitude of the lead displacements are similar.
PACS: 77.80.-e – Ferroelectricity and antiferroelectricity / 61.12.-q – Neutron diffraction and scattering
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2004