We review the diversity of the electrical behaviour of NBT induced by various defect mechanisms, including A-site Na or Bi non-stoichiometry, isovalent-substitution, and acceptor- and donor-doping.

Low levels of acceptor-type dopants can introduce appreciable levels of oxide-ion conductivity into NB0.51T due to a synergistic effect from defect chemistry and ceramic microstructure.

The use of time constant related parameter fmax to obtain the activation energy for bulk electrical conduction (and any discussion of the possible conduction mechanisms) in ferroelectric materials should be used with caution.

Bulk conductivity (σb) values of nominally stoichiometric Na0.5Bi0.5TiO3 (NBT) prepared by solid-state reaction collated from literature show random variation between 10-6 -10-3 S cm-1 (at 600 °C). This makes it...

The compositional limits of a previously reported (J. Am. Ceram. Soc., 61, 5-8. (1978)) but relatively unstudied sodium-bismuth titanate pyrochlore solid solution are revised and their electrical properties presented. The pyrochlore solid solution we report forms via a different mechanism to that originally reported and occurs in a different location within the Na 2 O-Bi 2 O 3-TiO 2 ternary system. In both cases, relatively large amounts of vacancies are required on the A-sites and on the oxygen sites, similar to that reported for undoped 'Bi 2 Ti 2 O 7 ' pyrochlore. In contrast to 'Bi 2 Ti 2 O 7 ', this ternary pyrochlore solid solution can be prepared and ceramics sintered using conventional solid-state methods; however, the processing requires several challenges to be overcome to obtain dense ceramics. This cubic pyrochlore series has low electrical conductivity (and does not exhibit any evidence of oxideion conduction) and exhibits relaxor ferroelectric behavior with a broad permittivity maximum of ~100 near room temperature. Variable temperature neutron diffraction data do not provide any conclusive evidence for a phase transition in the pyrochlore solid solution between ~4 and 873 K.