Surface Microsonics in Isotropic Media.
Quarterly rept. no. 2, 18 Feb-17 May 70,
RAYTHEON CO WALTHAM MASS RESEARCH DIV
Pagination or Media Count:
A program has started on hot-pressed ferroelectric LiNbO3 and LiTaO3. The LiNbO3 has been hot pressed to near theoretical density but attempts to pole the ceramic have been unsuccessful to date. Hot pressing LiTaO3 has just started. Measurement of the surface acoustic wave attenuation has been made on two samples of hot-pressed PZT. The loss at 41 MHz was high, 29 dBcm in the iron dopant sample and 51 dBcm in the control but similar to values obtained in conventionally sintered material. The loss appears to be dominated by contributions from the dielectric losses in the materials. Calculations of the effects of grain boundary scattering have been extended to noncubic crystallites. Problems have been encountered while chemical etching PZT and ZnO during photolithography. These are now under control and positive photoresists are being used. Author