A novel approach to fabricating high Q/sub m/ PZT

SAW devices are being investigated for TV-IF filters and mobile telephone applications. Additions of MnO/sub 2/ to PZT can result in materials with zero temperature coefficients and low propagation losses. The available Q/sub m/'s of PZT materials however, can limit their usefulness in energy-critical applications. In this work, a novel approach to improving the performance of PZT was attempted. The effect of both a dopant atom (Mn) and electron dopant pyrochlore phase, Sr/sub 2/Sb/sub 2/O/sub 7/, were examined. MnO/sub 2/ was added at 0.1, 0.3, and 0.5 wt% levels while the pyrochlore was added at the 5 mol% level. It was postulated that the pyrochlore phase might limit grain growth and reduce domain motion, thus increasing Q/sub m/. It was further postulated that compositions with both the pyrochlore and Mn doping should yield even greater Q/sub m/ values. Properties of interest, k/sub p/, Q/sub m/, e, and loss, were measured by the resonance method. In summary, Mn doping was effective in improving properties. Pyrochlore additions did reduce grain size; however, the properties were degraded.