Low loss tunable (Ba,Sr)TiO3 ceramics utilizing intragrain concentration gradient

The miniaturization of electronic devices has led to a need for tunable die lectric materials. These materials must exhibit high tunability and low los s in the microwave region. We observed high tunability and low loss through out the microwave region, from .3 MHz to 3 GHz, in (Ba,Sr)TiO3 ceramics wit h intragrain concentration gradients. The tunability varied slightly with f requency and was measured to be similar to 10% at 3 GHz under 10kV/cm bias and the loss tangent remained virtually unchanged, below .02 in this region . Our data is consistent with the theory of ion hopping clusters([1]). The graded composition results in suppression of ferroelectric resonance and th us dispersion of peak dielectric loss. The concept of intragrain concentrat ion gradient materials can lead to a variety of applications in the microwa ve communications field.