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 (Pb0.67Ca0.15Sr0.06Sm0.08) (Ti0.98Mn0.02)O3 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, kt (>0.55), and small planar electromechanical coupling coefficient, kp. 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.