Ba 1-x SrxTiO3(x=0.6 to 0.9 interval of 0.1) ceramics were developed by a BT sol-assisted sintering technology with a mixed-phase sintering from the mixture of BT and ST powders synthetized by a solid-state reaction method. The sintering behavior and dielectric properties of the ceramics were investigated. Results show that the sintering activity of the ceramics becomes worse and worse when increased the strontium content, and the sintering condition have a remarkable effect on the density of the ceramics. Dense ceramics were obtained when sintered at 1280°C for 8h with a relatively density of above 94%. The composition had a strong effect on the dielectric properties, while the sintering schedule had a little influence on the dielectric temperature spectrum of the BST ceramics. The Ba 1-x SrxTiO3(x=0.9) ceramic with dielectric constant～335, loss tangent～0.000625 at 1.85 GHz and 20°C, and good temperature stability of dielectric constant above the room temperature is attained.

Functionally graded piezoelectric ceramics (FGM) plates are attractive due to their ability to broaden the frequency bandwidth of the ultrasonic transducers. A resistivity gradient La-doped Lead Zirconate Titanate/Al-doped Zinc Oxide (La-PZT/Al-ZnO) piezoelectric ceramics plate was developed using a powder metallurgical process. Grading of the piezoelectric modulus across the plate was experimentally confirmed by the electrical impedance analysis and its gradient distribution was characterized using the profile-technique. The distribution of Zn2+ ions in the PZT region was examined using EPMA, XRD and SEM/EDX, respectively. Analysis results show that the gradient distributions of structural and electrical properties inside the FGM plate are mainly caused by the diffusion and aggregation of Zn2+ ions in the PZT layer. The functionally graded piezoelectric ceramics plate presented here will be useful for broadening the frequency bandwidth of piezoelectric transducers.

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