At the beginning of the project, as planned in the working program of the proposal, the research activity has been focused on the study of the commercial PZT systems and their potential applications. To this regard a manuscript has been published concerning the application of a lead-based piezoceramic for detecting the sequence of hits in a mechanochemical reactor. The as mentioned manuscript has been published as gold open access. At the same time, the attention has been moved to lead-free piezoceramics systems for transducers in medical imaging. This was motivated to the fact that, lead oxide, the main reagent of PZT, is toxic and its use is restricted in many countries of UE. Following the methodologies mentioned in the proposal, two main approaches have been used to prepare the lead-free system based on Potassium Sodium Niobate (KNN): i) the classical solid state route using the combination of mechanical treatment and thermal annealing and ii) the wet chemistry method exploring new and sustainable way. Furthermore, an efficient dopant was finally selected to be used as agent for improving the electromechanical properties of the KNN samples. Firstly, the attention was focused on the preparation of porous undoped KNN. This was demonstrated feasible for the first time in the current literature and its final characterization is still under progress. The summary of this period have been presented, as poster contributions, to the MSCA alumni conferences placed at Salamanca (2017) and Leuven (2018). Secondly, a new and facile synthesis of KNN by a modified Pechini method has been developed. By this approach it was possible to tune the stoichiometry of the final system, using water as green solvent and obtaining a very high piezoresponse. The latter compared with the data reported in the current literature, represents one of the most promising for undoped KNN densified by hydraulic press. This work was published and presented by an oral contribution in an international conference, EMRS 2018. The end of the project was focused on the fabrication of KNN-doped sensors synthesized by a solid state route. The systems have been characterized in collaboration with the prestigious center of materials of CSIC in Madrid. The class of materials tested in this period have been doped with MgNb2O6 (MN) and Li-based additives. If for the latter similar properties have been achieved with respect the data reported in the specific literature, for the first system named KNN-MN, very promising results are emerged. In particular a detailed study on the properties of KNN doped with different amount of MN revealed that the composite KNN-0.1MN possesses the best electromechanical properties. The system has been also object of investigation for its up-scaling fabrication. In the next future, this system will be teste under real condition. These results have been presented, as oral contribution, in the conference on piezoceramics Spain-Portugal (2018) and it will be published by February 2019.
