Lead-free piezoceramics - Where to move on?

Lead-free piezoceramics aiming at replacing the market-dominant lead-based ones have been extensively searched for more than a decade worldwide. Some noteworthy outcomes such as the advent of commercial products for certain applications have been reported, but the goal, i.e., the invention of a lead-free piezocermic, the performance of which is equivalent or even superior to that of PZT-based piezoceramics, does not seem to be fulfilled yet. Nevertheless, the academic effort already seems to be culminated, waiting for a guideline to a future research direction. We believe that a driving force for a restoration of this research field needs to be found elsewhere, for example, intimate collaborations with related industries. For this to be effectively realized, it would be helpful for academic side to understand the interests and demands of the industry side as well as to provide the industry with new scientific insights that would eventually lead to new applications. Therefore, this review covers some of the issues that are to be studied further and deeper, so-to-speak, lessons from the history of piezoceramics, and some technical issues that could be useful in better understanding the industry demands. As well, the efforts made in the industry side will be briefly introduced for the academic people to catch up with the recent trends and to be guided for setting up their future research direction effectively.ope

Effects of uniaxial stress on dielectric properties of ceramics in PMN-PZT system

In this study, effects of uniaxial stress on the dielectric properties of ceramics in PMN-PZT system were investigated. The ceramics with a formula (1-x)Pb(Mg1/3Nb2/3)O3-(x)Pb(Zr0.52Ti0.48)O3 or (1-x)PMN-(x) PZT when x = 0.0 0.3 0.5 0.7 and 1.0 were prepared by a conventional mixed-oxide method. Phase formation behavior of these ceramics was studied by an X-ray diffraction (XRD) method. In addition, other physical properties, e.g. firing shrinkage and density, were measured. The dielectric properties under the uniaxial stress of the poled PMN-PZT ceramics were observed at low and high-stress levels using a uniaxial compressometer. It was found that at low stress level (0-800 kPa) there was no significant change in the dielectric constant and the dielectric loss tangent with the applied stress. As the stress level was raised higher (0-5 MPa), changes of the dielectric constant with the applied stress were dependent on the ceramic compositions. On the other hand, changes of the dielectric loss tangent with the applied stress were independent of the ceramic compositions