Microwave Dielectric Properties of CaB 2 O 4 -CaSiO 3 System for LTCC Applications.

A novel composite ceramic with low densification temperature was fabricated using the conventional solid-state method. The XRD and Rietveld refinement results indicated that the two phases of CaB₂O₄ and CaSiO₃ can coexist in all compositions. Furthermore, a phase transition of CaSiO₃ ceramic from α-phase to β-phase was observed. A dense ceramic with excellent microwave dielectric properties (ε_r~6.4, Q × f~75,600 GHz, and a negative τ_f~26.9 ppm/°C) was obtained at x = 0.5 when sintered at 925 °C at the frequency of 14.2 GHz. A good chemical compatibility between the composite ceramic and Ag electrode was improved by elemental mapping results. A patch antenna was fabricated based on the simulated result. All results indicated that the 0.5 CaB₂O₄ + 0.5 CaSiO₃ ceramic has large application potential in the LTCC field. [ABSTRACT FROM AUTHOR]