Laser sinterig and PTCR effect characterization of BaTiO3:La ceramics

Abstract

Barium titanate (BaTiO3 – BTO) is a ferroelectric material widely applied in the electronics industry both in single crystal and ceramic forms. Due to its very high permissivity (e =1500-4000), it has been used extensively as dielectric in ceramic capacitors with outstanding properties. When partially doped with trivalent cations at the barium sublattice, BaTiO3-based ceramics exhibit a PTCR (positive temperature
coefficient of resistivity) semiconductive character close to Curie temperature. Due to this characteristics, these materials possess vast application on electronics devices like: temperature and liquid level sensors and current and voltage controller. The main of this work was the synthesis by solid state reaction, the laser sintering and the electrical characterization of La3+ doped BaTiO3 ceramics (BT:La) in order to verify the laser processing influence on its semiconductivity properties. In the laser sintering process, a CO2 laser is used as the main heating source and the ceramics bodies are submitted at very high heating and cooling rate (at about 2000°C/min). X-ray Diffraction, Scanning Electron Microscopy and Impedance Spectroscopy techniques were employed to characterization process.