PbNb2O6 ceramics with tungsten bronze structure for low Q(m) piezoelectricmaterial

A broadband ultrasonic transducer was made from [(Pb-x,Ba1-x)(1-3y/2)La-y]N b2O6 which was prepared by substituting Ba and La for Pb in PbNb2O6. Analys is of the piezoelectric performance as a function of ceramic composition re vealed that samples with x = 0.40-0.80 and y = 0-0.10 have the maximum elec tromechanical coupling factor (k(t)). The k(t) of this sample was 0.45, and the k(p), was 0.32. Since k(p) was relatively high with respect to k(t) a high-order radial mode appeared in the vicinity of the thickness mode reson ance frequency. Slots were cut into both sides of the disk to reduce this p henomenon. The slotted disk had a reduced radial vibration mode, and the k( p) decreased to 0.06. The k(t) increased to 0.61, and the mechanical qualit y factor (Q(m)) was 20. This ceramic can be used as an efficient broadband transducer.