Fabrication of modified lead titanate piezoceramics with zero temperature coefficient and its application on SAW devices

The Samarium-modified, lead titanate ceramics with a composition of (Pb/sub 0.67/Ca/sub 0.15/Sr/sub 0.06/Sm/sub 0.08/) (Ti/sub 0.98/Mn/sub 0.02/)O/sub 3/ were prepared by conventional mixed-oxide method. By properly varying the sintering and poling conditions, the samples with zero temperature coefficient of resonant frequency were fabricated. The piezoelectric and dielectric properties were measured; it showed that the samples with zero temperature coefficient still keep high-thickness, electromechanical coupling coefficient, k/sub t/(>0.55), and small planar electromechanical coupling coefficient, k/sub p/. Surface acoustic wave (SAW) filters were fabricated; and the properties, including phase velocity and electromechanical Coupling coefficient, were measured. Microstructural and compositional analyses have been carried out using scanning electron microscopy and x-ray diffraction.