Microwave dielectric properties of BaTiO3-SrZnP2O7 composite ceramics for tunable microwave applications

This paper reports on microwave properties of (1 - x)BaTiO3 (BT)-xSrZnP2O7 (SZP) composite ceramics, with x = 0, 5, 10, 20 and 25 wt%, fabricated via the conventional solid-state reaction process. Two new phases, Ba3(PO4)2 and Zn3(PO4)2, were found to be present in the composite ceramics. With increasing content of SZP, the peak values of permittivity gradually decreased and the peaks shifted to lower temperatures. At the same time, their loss tangents were reduced and thus their Q factors were increased. The sample with x = 25 wt% exhibits promising dielectric properties, with permittivity, loss tangent and tunability at 5 kV mm-1, of 68, 0.002 and 15%, at 10 kHz and room temperature. At ∼4 GHz, it possesses a permittivity of 58 and a Q factor of 223, which makes it a good candidate for tunable microwave device applications.