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Novel Doping Mechanism for Very‐High‐Permittivity Barium Titanate Ceramics
Author(s) -
Morrison Finlay D.,
Sinclair Derek C.,
Skakle Janet M. S.,
West Anthony R.
Publication year - 1998
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1998.tb02575.x
Subject(s) - barium titanate , materials science , lanthanum , doping , curie temperature , analytical chemistry (journal) , permittivity , barium , vacancy defect , ceramic , mineralogy , titanate , dielectric , inorganic chemistry , crystallography , condensed matter physics , metallurgy , chemistry , physics , optoelectronics , chromatography , ferromagnetism
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 (ɛ′) maximum at T c occurs. For the composition Ba 1‐ x La x Ti 1‐ x /4 O 3 , where x = 0.05, ɛ′ 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.