Barium titanate (BaTiO 3) can be doped with La 3+ ions via partial substitution for Ba 2+ ions; charge balance is maintained by the creation of Ti 4+ vacancies. Samples processed in an atmosphere of 1 bar O 2 and a temperature of 1350°C are insulating and free from electronic defects associated with either O 2 loss or reduction of Ti 4+ to Ti 3+. The Curie temperature (T c) decreases approximately linearly as the lanthanum content increases and, at the same time, an increase in the permittivity (ε′) maximum at T c occurs. For the composition Ba 1-xLa xTi 1-x/4O 3, where x = 0.05, ε′ has a maximum value of 19000 at 18°C, compared with a typical value of 10000 at 130°C in undoped BaTiO 3 ceramics. This value is the highest value reported for A-site-doped BaTiO 3 and is linked to the mechanism of combined A-site doping and Ti-vacancy creation.
|Number of pages||4|
|Journal||Journal of the American Ceramic Society|
|Publication status||Published - 31 Jul 1998|