title: Pre-focused lead titanate > 25 MHz single-element transducers from hollow spheres.
abstract: Miniature lead titanate (PT) hollow spheres with diameters in the 1 to 10 mm range and wall thicknesses of 20 to 120 microns have been fabricated. Shell sections were used as components of pre-focused transducers. Spheres are produced using a new sacrificial core technique that produces hundreds of spheres with a more uniform wall thickness than those produced by earlier methods. Shells produced from these spheres were found to have a wall thickness variation of about 10%. Despite this variation, bulk properties were estimated from capacitance and impedance data. Shells tested in this work had dielectric constants (1 kHz) near 280 with loss factor of < 2% and d33 values of 68 pC/N. Thickness coupling coefficients averaged 0.51 with mechanical quality factors of < 15. A transducer fabricated from these sections of spheres had a round-trip insertion loss of -20.1 dB at the center frequency of 39.8 MHz and a 6 dB bandwidth of 33%.
authors.affiliation: Materials Research Laboratory, Pennsylvania State University, University Park, PA 16802-4801, USA. rmeyer@psu.edu
authors.forename: R
authors.initials: R
authors.lastname: Meyer
authors.forename: R
authors.initials: R
authors.lastname: Newnham
authors.forename: S
authors.initials: S
authors.lastname: Alkoy
authors.forename: T
authors.initials: T
authors.lastname: Ritter
authors.forename: J
authors.initials: J
authors.lastname: Cochran
mesh_terms: D001698:Biomedical Engineering; D004867:Equipment Design; D006801:Humans; D007854:Lead; D008855:Microscopy, Electron, Scanning; D014025:Titanium; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation*
chemical_list: D007854:Lead; D014025:Titanium