POROSITY CONTROL IN PIEZOELECTRIC FILMS

摘要

A piezoelectric film having a porosity between 20 and 40%, a thickness ranging from tens of microns to less than a few millimeters can be used to form an ultrasonic transducer UT for operation in elevated temperature ranges, that emit pulses having a high bandwidth. Such piezoelectric films exhibit greater flexibility allowing for conformation of the UT to a surface, and obviate the need for couplings or backings. Furthermore, a method of fabricating an UT having these advantages as well as better bonding between the piezoelectric film and electrodes involves controlling porosity within the piezoelectric film

主权项

1. An ultrasonic transducer (UT) comprising a piezoelectric film sandwiched between two electrodes, wherein the film:
is 2 microns to 2 mm thick, has a controlled porosity of 15-40% with micron-scale or sub-micron scale pores; and is principally composed of piezoelectric powders having micron or submicron sizes mixed with a residue of a binder, wherein the binder residue comprises residue of a liquid or del oxidizing agent that forms an intermediate oxidation layer on at least one of the electrodes, said at least one electrode being a high electrical conductivity material with minimal and non-fragile oxidation at temperatures throughout a desired operating temperature of the UT,so that the UT is endowed with a broad ultrasonic bandwidth of at least 30%.