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ECE Research Component of PhD Qualifier Exam By: Eric Kobina Aikins

When: Friday, October 25, 2019
1:00 PM - 3:00 PM
Where: Science & Engineering Building, Lester W. Cory Conference Room: Room 213A
Cost: Free
Description: Topic: Effect of Axial Pressure Treatment on Effective Coupling Coefficient of Piezoelectric PZT-5A for Electroacoustics

Location: Lester W. Cory Conference Room, Science & Engineering Building (Group II), Room 213A

Abstract:
It was previously shown by R. Y. Nishi1 that effects of a high, static, one-dimensional stress on the properties of piezoelectric ceramics are important in the design of some types of underwater transducers. In a conventional mass-loaded resonator incorporating ceramic as the active element, the stress in the ceramic owing to the static water pressure in the direction of the polar axis of the ceramic, and can be larger than the water pressure when the ceramic cross-sectional area is smaller than the radiating face of the resonator. Changes in the high-field permittivity and loss due to hydrostatic pressure superimposed on a one-dimensional bias pressure were small, provided that the bias pressures were applied to the ceramics at least one week before the hydrostatic pressure.

PZT-5A ceramic subjected to one-dimensional stress becomes anisotropic with substantial increase of the piezoelectric modulus d32 of its original value after exposure to static pressure in a direction perpendicular to the polar axis. Practical appreciation of this effect is not known from literature.

Moreover, experimental work on the effect of hydrostatic pressure on the piezoelectric and high-field dielectric properties of two piezoceramic projector materials was presented by R. F. Brown2. Two materials, a modified barium titanate and modified lead zirconate titanate, were characterized by low dielectric losses at high fields. In the pressure range 0 to 10 000 psi and at non-resonant driving fields up to 3 kV/cm, the variations observed in the permittivity and piezoelectric strain constants with hydrostatic pressure were less than 7%, and no significant variations were found in the dielectric loss. Aging studies at 10,000 psi showed that the permittivity and dielectric loss for both materials reached constant values after a few minutes.

This research is concerned with investigating the possibility of using axial pressure treated PZT-5A rings to improve the electromechanical parameters for electroacoustic applications. An xperimental technique of pressure treatment that allows dynamic measuring parameters of the ring in the process of exposure to the pressure is described. Results of the pressure treatment on parameters of the cylinders are presented. It is shown that the improvement in the PZT-5A coupling coefficient is about WHAT due to pressure treatment was stable over time.

NOTE: All ECE Graduate Students are ENCOURAGED to attend.
All interested parties are invited to attend. Open to the public.
Advisor: Dr. David A. Brown
Committee Members: Dr. Paul J. Gendron and Dr. Yifei Li, Department of Electrical & Computer Engineering, UMASS Dartmouth; Dr. Boris Aronov, Consulting Scientist, Artech Engineering Plus

*For further information, please contact Dr. David Brown at 508.999.8479, or via email at dbrown@umassd.edu.
Topical Areas: General Public, University Community, College of Engineering, Electrical and Computer Engineering