Study and manufacturing of strontium calcium titanate lead-free ceramic capacitors for high-frequency applications

SrTiO₃ based lead-free ceramics has enormous potential for dielectric capacitors. This work focuses on the fabrication of small size Sr_1-xCa_xTiO₃ (SCT) ceramic capacitors. Initially, the ceramics with a high doping concentration of 0.36 ≤ x ≤ 0.40 were prepared using the sol-gel method and characterized for their structural, morphological (grain), and dielectric properties. An increase in calcium doping concentration revealed a notable decline in the dielectric dissipation factor. Further, small size ceramic capacitors with ≈ 1mm² dimensions were micro-machined in order to replicate the size of high-frequency commercial capacitors and to emphasize the real potential of this class of ceramics for dielectric capacitors. The dielectric properties, measured from 100 Hz to 1 GHz, such as permittivity (ε′), loss tangent (tgδ), and quality coefficient (Q) revealed that these materials could have a great interest in the development of monolithic ceramic capacitors dedicated to a very large frequency range from 100 Hz to 1 GHz applications.