Electrical and structural characteristics of lanthanum-doped barium titanate ceramics
Abstract
Single phase La-doped BaTiO3 with the formula Ba1-xLaxTi1-x/4O3: 0⩽x⩽0.20 was prepared by solid state reaction of oxide mixtures at 1350 °C, 3 days, in O2. The tetragonal distortion in undoped BaTiO3 decreased with x and samples were cubic for x⩾0.05. Both the tetragonal/cubic and orthorhombic/tetragonal transition temperatures decreased with x, but at different rates, and appeared to coalesce at x∼0.08. The value of the permittivity maximum at the tetragonal/cubic phase transition in ceramic samples increased from ∼10 000 for x=0 at 130 °C to ∼25 000 for x=0.06 at ∼-9 °C. At larger x, the permittivity maximum broadened, showed "relaxor"-type frequency dependent permittivity characteristics and continued to move to lower temperatures. Samples fired in O2 were insulating and showed no signs of donor doping whereas air-fired samples were semiconducting, attributable to oxygen loss.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- December 1999
- DOI:
- 10.1063/1.371698
- Bibcode:
- 1999JAP....86.6355M
- Keywords:
-
- 77.84.Dy;
- 77.80.-e;
- 64.70.Kb;
- 77.22.Ch;
- Niobates titanates tantalates PZT ceramics etc.;
- Ferroelectricity and antiferroelectricity;
- Solid-solid transitions;
- Permittivity