Low Loss Ferroelectric Material Development for Accelerator Applications

75565B Low loss ferroelectric materials based on BST (barium strontium titanate) could be used as the basis for new advanced technology microwave and particle accelerator devices. The electronic properties of this material would allow one the creation of an X-band, high-power RF switch with peak power sufficient for use in linear collider RF systems. This project will develop a new BST material with a permittivity of ~500 and a loss factor of 1¿10-3 at 11.4 GHz. In addition, a process for sintering and forming large size objects (required for phase shifter components) made of BST ceramic will be demonstrated. In Phase I, a nonlinear ferroelectric material, intended for accelerator applications, was produced. The required tunability (De/e of 22- 29 % at 4-5 4.5 V/mm dc bias field, for thin substrates) and dielectric losses (5¿10-3 at X-band) have been achieved. Forming and sintering technology was developed for large ferroelectric components. Phase II will improve the nonlinear ferroelectric BST-MgO (BSM) composition and demonstrate it¿s appropriateness for linear accelerator applications. The ferroelectric tunability of the new material will be increased (De/e up to 1.25-1.35 at 4.5-5.5 V/mm bias) and the loss factor will be reduced (to 3-4¿10-3 at 10 GHz). Commercial Applications and Other Benefits as described by the awardee: The ferroelectric-based tunable device technology should have application to a variety of high-frequency, large-signal devices in the military and wireless communication industries.