Neutron diffuse scattering from PbMg 1/3 Ta 2/3 O ₃ relaxor ferroelectric

We report first single-crystal measurements on the PbMg 1/3 Ta 2/3 O 3 relaxor ferroelectric by means of neutron scattering. We observe neutron diffuse scattering around the (110) Bragg position in the temperature range T = 20–295 K. The diffuse scattering is found to be elongated in the transverse direction, as it is expected for polarization fluctuations in the presence of dipole-dipole forces. The susceptibility associated with this scattering decreases linearly with increasing temperature from T = 100 K up to 220 K. The corresponding correlation length ξ reaches a maximum of 42 Å near T = 100 K. At room temperature, the diffuse scattering has a finite energy width indicating a relaxation time of τ ∼ 6.4 × 10 −12 s.