Evaluation of the Sr2TiSi2O8 ceramic matrix for radiofrequency and microwave applications

This paper reviews the dielectric properties of Sr2TiSi2O8 (STS) ceramic in the radio frequency (RF) and microwave (MW) regions. X-ray diffraction (XRD) analysis is used to demonstrate that a small secondary phase of SrTiO3 is present in a synthesised STS ceramic. Complex impedance spectroscopy is performed, and the typical permittivity values of ceramic materials are observed. Nyquist diagrams are fitted based on an equivalent circuit using two associations of R-CPE related to the grain and the grain boundary effects. A dependence study of the changes in AC conductivity with frequency at different temperatures demonstrates that the conduction process is thermally activated, and a value of 1.0 eV is obtained for the activation energy. In the MW range, we observe values of epsilon(r) = 12.7, tan delta = 1.3 x 10(-2), and tau(f) = - 6.1 ppm/degrees C, indicating interesting properties for applications in devices that operate in the MW region. A numerical simulation is employed to evaluate STS ceramic as a dielectric resonator antenna, and we observe a reflection coefficient of below - 10 dB, a realised gain of 4.6 dBi, a bandwidth of 475 MHz, and a radiation efficiency of around 75%. The properties of the STS matrix presented here indicate that this ceramic would be a suitable candidate for the operation of devices in the C-band, as well as in devices operating in the RF range.