In recent years, remarkable developments have taken place in electromechanical system research. Among them, piezoelectric ceramics and their devices have drawn huge attention. Actuators utilizing piezoelectricity as driving elements have found a wide spectrum of applications. Piezoelectric bimorph, using two piezoelectric plates to produce bending displacement, is one of the most widely applied actuator designs. This type of actuator can provide large displacement, and can be applied in many

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... as such as valves, positioners and benders. The recent advances in technology require the actuator to be applied in miniaturized and severe environments with high reliability. However, the currently available actuators have limitations in either low reliability or miniaturization. In the present work, the concept of functionally gradient material (FGM) monomorph actuator was proposed via a promising technique known as electrophoretic deposition (EPD). It is expected that this ceramic FGM monomorph actuator will find a wide range of applications due to its simple production process and superior properties. The aim of this project is to establish the procedure to fabricate the miniaturized FGM monomorph actuator using EPD technique, and also characterize and model the electromechanical properties of the actuator. Several important aspects of the actuator will be introduced and studied. They are: (1) the synthesis and property characterization of the starting materials; (2) the fabrication and characterization of the monomorph; (3) the relationship between piezoelectric property distribution of the materials, structure of the monomorph and electromechanical output properties of actuator; (4) the stress distribution and its significance. Based on the above understanding, the optimized structure will also be proposed. The project was carried out using the following procedure. Eleven PZT compositions were first prepared and characterized. Then three material systems were determined to fabricate monomorph actuators using electrophoretic deposition. The deposition procedure and conditions were investigated. After fabrication, the FGM monomorph was characterized both on its physical and electromechanical properties. To analyze the results, a theoretical model was proposed and compared with the experimental results. The stress distribution of the monomorph was also studied and discussed. i ATTENTION: The Singapore Abstract Important results and conclusions are summarized below. The designed FGM monomorph actuators fabricated exhibit gradient distribution in both microstructure and material properties (Young's modulus Y, piezoelectric constant d 31 and dielectric constant E:), which results in a functional gradient and smooth stress distribution over the cross section. EPD is an efficient method to fabricate FGM monomorph actuator with uniform configurations. A gradient microstructure over the overall cross section was also observed. Depending on configurations of the actuator, the developed monomorph actuators generate displacement within the range from 2 pn to 40 pm at 100 V in static case. Compared with the monomorph reported, it has higher sensitivity, displacement and miniaturized dimensions.