Complex permittivity of some ferroelectric materials at 3.0 GHZ
Mancill, Clanton Evans
Davis, L. E.
Master of Science
The complex permittivities of BaTi03 ceramic, BaTi03 single crystal, (Ba.77Sr.23)Ti03 solid solution, and (Ba .77Sr)Ti03 doped with In203 were measured as functions of temperature at 3.0 Ghz. The permittivities were measured over the approximate temperature range -120°C to +150°C. The complex permittivities were obtained by making admittance measurements with a system consisting of a disc sample in a radial-line configuration at the end of a coaxial line. The measured real dielectric constants varied from 400 to 3800. The loss tangents were in the range 0.3 to 0.6. The permittivity and loss tangent reached their maximum values at 120°C in the BaTi03 samples. In the (Ba.77Sr.23)Ti03 solid solution, permittivity and loss reached their maximum values at 32°C. Measurements were also made on (Ba.77 Sr .23 )Ti03 doped with In203 in order to maximize the bulk relaxation time of the material. Results were nearly identical to those obtained with undoped (Ba.77Sr.23) Ti03, indicating that the change in the bulk relaxation time had no effect on the microwave relaxation properties of (Ba.77Sr.23)Ti03.