Manufacturing of lead free transparent piezoceramics by densification and crystallisation of laserfused microspheres

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In vehicles and machines vibrations occur which can lead to noice emission. To reduce these effects adaptronic systems with piezoceramic actuators shall be used. At the moment piezoceramics in most cases are lead containing systems like PZT. Because of the environmental harmfulness there is big scientific interest in lead free piezoceramics. The research focus in the moment are KNN systems. Transparent piezoceramics shall be used e.g. as vibration damping systems on windows.In this proposal the development of amorphous microspheres with stochiometric composition KNN will be investigated via laser fusing. By means of a CO2 laser the starting materials will be melted and form because of the surface tension of the liquid phase microspheres. The well defined laser beam profile leads to high cooling rates which can prevend crystallisation. The microspheres will be investigated considering transparency, homogeneity, particle size as well as glass transition and crystallisation temperature. The temperature difference between glass transition and crystallisation is called kinetic window and will be used for densification of the microspheres to obtain amorphous samples with a larger volume. The crystallisation of the material will be investigated by defined temperature treatments with regard to the piezoelectric properties and the transparency of the material.