Study Of Lead-free Piezoelectric Ceramice Devices

Piezoelectric ceramics are a type of advanced functional materials, which canrealize the transformation between mechanical energy and electric energy. They werewidely used as electronic component material in the sensor, transducer and so on.However, currently-available piezoelectric materials are mainly lead-based ceramics,in which a great amount of toxic lead contains. It has become a serious environmentaland health issue that can no longer be ignored. Many researchers have made a lot ofeffort to study the lead-free piezoelectric ceramics due to limit of lead materials, andthe performance of lead-free piezoelectric ceramics are improved. Therefore, theinvestigation and development of the lead-free piezoelectric devices to substitute forPZT-based devices have been an urgent task all over the world.NBT is considered as one of the most likely candidates for replacing Pb-basedmaterials, which own better performance for other lead-free piezoelectric ceramics.Compression-type accelerometers are widely used in various vibration systems, whichpossess simple structure was chosen to develop lead-free devices. In this dissertation,BNT-based piezoelectric ceramic was used as sensitive element, to fabricate acompression-type accelerometers. Finite Element Analysis was employed to study theeffect of the mass of the preloading element and the thickness of the sensitive piezo-rings on the sensitivity and usable frequency range of the piezoelectric accelerometer.We got optimal parameter, which were opted to made compression accelerometer.Specific contents are as follows.1. BNT-based piezoelectric ceramics were prepared by a conventional mixedoxide method. The samples were made according to vibration model, which were usedto get electrical and physical properties, such as piezoelectric strain matrix, relativepermittivity, mechanical quality factor, Electro-mechanical coupling factor, density,elasticity matrix and Poisson’s ratio.2. ANSYS10.0software was exploited in the finite-element method. Frist, thefinite element model of accelerometer was founded. Second, the sensitivity of4pC/m·s-2with the usable frequency range of1Hz-5000Hz were selected as objectiveperformance. Analysis of accelerometer was calculated, to get the results. Finally, theresults were discussed, to find best result.3. The elements of accelerometer were made, which were assembled. The sensitivity and the usable frequency range of accelerometer were tested.Finite Element Analysis is a powerful and efficient method in the research ofpiezoelectric devices. However, there is deviation between the calculated and theactual results. The deviation can be considered in the design process, to get the resultwhich we expect.