USE OF PIEZOELECTRIC AND FERROELECTRIC MATERIALS IN ULTRASONIC TRANSDUCERS

W. Mason

After recalling Langevin's first works with quartz transducers, this paper describes transducer materials which have been developed later. The piezoelectric parameters, such as Curie temperature, or electromechanical coupling factor of Rochelle salt and ADP (ammonium dihydrogen phosphate) are exposed. Using ADP, many kilowatts of acoustic energy have been obtained in 10-4 s duration pulses. Ferroelectric materials are described, starting with barium titanate. The preparation of the material is described. Piezoelectric, dielectric and expansion constants are studied as a function of temperature leading to the limitations of such a material for transducer work. A similar description is given for lead titanate-lead zirconate solid solutions. The phase diagram shows the existence of a critical concentration of PbTiO3. The influence of some impurities is investigated. Using such ceramic transducers operating in pulses peak power of megawatts can be obtained in pulsed work. For very high frequencies (above 100 MHz) single crystals of lithium niobate or lithium tantalate can be used. Barium sodium niobate has been used as a non-linear crystal. Finally, operation above 500 MHz requires evaporated or sputtered thin film transducers.

Domaines: Articles anciens

W. Mason. USE OF PIEZOELECTRIC AND FERROELECTRIC MATERIALS IN ULTRASONIC TRANSDUCERS. Journal de Physique Colloques, 1972, 33 (C6), pp.C6-15-C6-24. ⟨10.1051/jphyscol:1972604⟩. ⟨jpa-00215122⟩