Experimental and theoretical approaches to investigating bulk and nanoscale properties of ferroelectrics

• Main Author: Ng, Nathaniel
• Other Authors: Freddy Boey
• Format: Theses and Dissertations
• Language: English
• Published: 2008
• Subjects: DRNTU::Engineering::Materials::Microelectronics and semiconductor materials::Nanoelectronics and interconnects
• Online Access: https://hdl.handle.net/10356/13540
• Institution: Nanyang Technological University

The rapid development of piezoelectric ceramics in the recent years, has led to a wide range of possible applications, particularly in the area of miniaturized applications where significant advances have been made. Piezoelectric tubular transducers are key components for microactuating devices such as ultrasonic motors and devices utilizing piezoceramics outperform their electromagnetic counterparts at miniaturized scales. Traditional tubular ultrasonic transducers have been reported to produce rotational speeds up to about 300rpm with torque in the uNm to mNm range, but recently, an ultrasonic tubular transducer reaching a speed of 4000rpm has been developed. Constitutive relationships are formulated using classical Timoshenko beam theory to describe the performance of such motors as a function of the electrical inputs, the material properties such as the piezoelectric constant and mechanical quality factor, and geometry. Experimental work is carried out to support this theoretical derivation, as well as to improve the understanding of the frequency-dependent and geometric-dependent behavior of Pb(Zr0.52Ti0.48)O3 (PZT) as well as polyvinylidene fluoride (PVDF) copolymers, a recent development in the field of ferroelectric polymers which allows the benefits of increased strain and energy density.