PIEZOCERAMIC, PIEZOELECTRIC COMPONENT CONTAINING SAME AND METHOD FOR PRODUCING THE PIEZOCERAMIC

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The invention concerns a piezoceramic comprising a piezoelectric phase containing a lead titanozirconate et nickel and lead niobate (PZT-PNN). The piezoceramic phase is represented by the following general empirical formula : Pb1-aDcZrxTiy (Ni1/3Nb2/3) ZO3, wherein : D represents at least one alkaline-earth metal having an alkaline-earth content c, a 0, c > 0 and 0.9 < (x + y + z) = 1.1 and 0.9 < (x + y + z) = 1.1. Said piezoceramic is characterized in that the piezoceramic phase represents more than 99 vol. % relative to the solids of the piezoceramic. The invention also concerns a piezoelectric component containing said piezoceramic, and a method for producing said piezoceramic, said method involving the use of mixed oxides. The method is characterized in that it consists in using starting materials of the type of piezoceramic metal oxides. The use in particular of NiO and NB2O5 causes the occurrence of intermediate pyrochlorine during the formation of the piezoceramic, which promotes the densification of the piezoceramic. A piezoceramic is thus obtained having a densification temperature less than 950 °C and a relatively high d33 coefficient. Said piezoceramic enables a monolithic piezoelectric element to be obtained wherein is used, as electrode material, silver, copper or a silver/palladium alloy with low palladium content. The inventive component comprising one or several piezoelectric elements can be in the form of a flexure transducer. It can also be in the form of an ultrasonic transducer designed to be used in medical technique. Said component can also be used as multilayer actuator for controlling a valve, in particular a motor vehicle internal combustion engine valve.