Grain boundary effects in ferroelectric barium titanate

The doping of ferroelectric barium titanate ceramics with iron of 0 to 0.35% mass fraction and the sintering at different temperatures from 1260°C to 1520°C yields a sintering spectrum of grain diameters between 50 μm and 0.3 μm, connected with a drastic change of the electrical properties. Coarse grained material shows the normal ferroelectric dependence of permittivity vs. temperature and of the polarisation vs. electrical field. The permittivity of fine grained samples varies much less in the temperature range between + 120°C and + 120°C and a sort of stabilization of the polarization can be determined. With X-ray microanalysis the iron distribution in the small grains has been measured and a model is proposed, which correlates this distribution to the electrical properties and the microstructure of the material.

Notes

Now at Siemens AG, Kunststoff und Porzellanwerk