Dielectric properties of CaCu3Ti4O12, Ba(Fe1/2Nb1/2)O3, and Sr(Fe1/2Nb1/2)O3 giant permittivity ceramics at microwave frequencies

摘要

The dielectric properties of CaCu3Ti4O12, Ba(Fe1/2Nb1/2)O3, and Sr(Fe1/2Nb1/2)O3 giant permittivity ceramics were evaluated at microwave frequencies using a modified resonant cavity method. In the frequency range between 3.4 and 9.5 GHz, the permittivities of the three ceramics were around 84.6, 43.9, and 40.4 at 20 °C and were nearly independent of frequency. The dielectric losses decreased and the Qf values increased significantly with increasing frequency. The temperature dependence of the dielectric properties was also investigated at about 6.02 GHz. With increasing temperature from -60 °C to 80 °C, the permittivities of CaCu3Ti4O12, Ba(Fe1/2Nb1/2)O3, and Sr(Fe1/2Nb1/2)O3 ceramics varied nearly linearly, and the corresponding temperature coefficients of permittivity were -700, 175, and 164 ppm/ °C, respectively.