Mechanical quality factor of lead zirconate titanate/epoxy composites

1-3 composites consist of ceramic rods embedded in a polymeric matrix. They have attracted considerable interest because they can be used to factibate ultrasonic transducers that have acoustic impedance close to that of human tissue and water. Their bandwidth can be tailored by varying the ceramic volume fraction. The mechanical quality factor Q sub m of 1-3 piezoelectric lead zirconate titanate/epoxy composites with ceramic volume fractions phi ranging from 0.18 to 0.82 has been measured. This range of phi is wider than those previously investigated by other workers. The width-to-thickness ratio of the ceramic phase is sufficiently small that there are no significant mode couplings. The observed Q sub m agrees well with the prediction of the parallel model. It is found that Q sub m increases from 34 to 100 as phi changes from 0 to 0.82 and then increases sharply to reach a high value of 600 at phi = 1. Therefore Q sub m can be tailored to give a wide range of values by varying phi