Synthesis of Barium Titanate Compounds with Enhanced Dielectric Properties at Room Temperature
The addition of 22 mol% of different zirconia containing powders: cubic stabilized zirconia (8YSZ), tetragonal zirconia (TZ3Y), and pure zirconia to barium titanate (BaTiO3) was studied. X-ray diffraction analysis of the sintered compact made of these powder mixtures confirmed the presence of single phase peroviskate-like structure. The microstructure of the sintered samples showed different grain sizes, for different kinds of zirconia additives. The relative permittivity and the dielectric loss of the sintered pellets were measured at different temperatures and frequencies. The highest relative permittivity was obtained for samples having 22 mol% 8YSZ. The yttria addition to barium titanate zirconate had been discussed.
Barium titanate screen-printed thick films
Abstract Barium titanate (BT) thick films were prepared from mechanically activated powders based on BaCO 3 and TiO 2 . After homogenization and milling in a high-energy vibro mill, the powders were calcined at 700 °C for 2 h by slow heating and cooling rates. A thick film paste was prepared by mixing BT fine powders with small amount of low temperature sintering aid and organic binder. The thick films were screen-printed on alumina substrates electroded with Ag-Pd. The BT films were sintered at 850 °C for 1 h. The thickness was 25–75 μm depending of number of layers. The microstructure of thick films and the compatibility between BT layers and substrate were investigated by SEM .Results of dielectric property measurements are also reported.
Strain and vacancy cluster behavior of vanadium and tungsten-doped Ba[Zr0.10Ti0.90]O3 ceramics
Strain and vacancy clusters behavior of polycrystalline vanadium (V) and tungsten (W)-doped Ba[Zr0.10Ti0.90]O3, (BZT:2%V) and (BZT:2%W) ceramics obtained by the mixed oxide method was evaluated. Substitution of V and W reduces the distortion of octahedral clusters, decreasing the Raman modes. Electron paramagnetic resonance data indicate that the addition of dopants leads to defects and symmetry changes in the BZT lattice. Remnant polarization and coercive field are affected by V and W substitution due the electron-relaxation mode. The unipolar strain E curves as a function of electric field reach its maximum value for BZT:2%V and BZT:2%W ceramics.