A systemic study was performed on bismuth strontium titanate (Sr_(1-1.5x)Bi_xTiO_3, 0.04 ≤ x ≤ 0.25) ceramics. Dielectric properties were measured from 83 to 373 K at different frequencies. A transformation from relaxor ferroelectrics to relaxor behavior was observed when x > 0.10. Both diffuseness and relaxation degree increase as x rises. Tunability was found to increase with increasing x value until 0.07, and then decrease when Bi~(3+) content increases. Meanwhile, their figures of merit (defined as tunability/loss) shows a maximum at x=0.12. The change from relaxor ferroelectrics into relaxor behavior has a positive impact on the tunability of bismuth strontium titanate system.
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Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China;