Pre-focused lead titanate > 25 MHz single-element transducers from hollow spheres.
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%.
Meyer
R
R
Materials Research Laboratory, Pennsylvania State University, University Park, PA 16802-4801, USA. rmeyer@psu.edu
Newnham
R
R
Alkoy
S
S
Ritter
T
T
Cochran
J
J
D001698:Biomedical Engineering; D004867:Equipment Design; D006801:Humans; D007854:Lead; D008855:Microscopy, Electron, Scanning; D014025:Titanium; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation*
D007854:Lead; D014025:Titanium