Synthesis and electrical characterization of Y, Eu-doped barium calcium titanate ceramics.

This work reports the synthesis and electrical characterization of Ba_0.77Ca_0.227Y_0.003TiO₃ (BCT:Y) and Ba_0.77Ca_0.227Eu_0.003TiO₃ (BCT:Eu) ceramics. The powders were synthesized by the polymeric precursor method and presented majority Ba_0.77Ca_0.23TiO₃ (BCT) phase after calcination at 600 °C for 4 h. Afterwards, the ceramics were sintered at 1350 °C under reducing atmosphere. X-ray diffraction, scanning electronic microscopy and impedance spectroscopy techniques were used to study the structural, microstructural, and electrical characteristics, respectively. The sintered ceramics exhibit homogeneous microstructure with high relative density and majority BCT phase. The BCT:Y sample presented PTCR (Positive Temperature Coefficient of Resistivity) behavior with room temperature resistivity of 1.1⋅10⁴ Ω⋅cm (grain) and 6.8⋅10⁵ Ω⋅cm (grain boundary), and a PTCR jump of about three and two orders of magnitude, respectively, suggesting a core–shell structure at the grain boundary region. On the other hand, BCT:Eu showed normal dielectric behavior that was associated with the Eu reduction during the sintering process. [ABSTRACT FROM AUTHOR]