title: Ultrasonic transducers based on undoped lead-free (K0.5Na0.5)NbO3 ceramics.
abstract: Lead zirconate titanate (PZT) ceramics are the dominant piezoelectric elements for non-destructive evaluation (NDE) and ultrasonic transducers devices. However, the presence of lead content may impose the scientific community to develop lead-free ceramics, concerning human health and environmental safety. During the past ten years, many contributions have highlighted the potential properties of complex compositions like LiNbO3, LiTaO3 and LiSbO3 in the lead-free (K0.5Na0.5)NbO3 KNN system. In this context, for the first time, the practical applications and the effectiveness of simply undoped (K0.5Na0.5)NbO3 (KNN) ceramics are investigated. KNN powder is prepared by conventional solid state mixed oxide route. Ceramics of this material are prepared using conventional sintering (CS) and spark plasma sintering (SPS). Thickness coupling factor kt of 44-46%, planar coupling factor kp of 29-45%, relative permittivity at constant strain ε33,r(S) of 125-243 and acoustic impedance Z of 23-30 MRay are obtained for these two kinds of undoped KNN ceramics. Both ceramics are used to build single-element ultrasonic transducers. Relative bandwidth of 49-78% and insertion loss of -27 and -51dB are obtained for SPS and CS transducers, respectively. These results are suitable for use in non-destructive evaluation. The effectiveness of undoped KNN is evaluated using the KLM model, and compared to standard PZT based probe. Finally, chemical aging test of undoped KNN has demonstrated its stability in water.
authors.affiliation: Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, IUT de BLOIS 15 rue de la chocolaterie, CS 32903, 41029 Blois Cedex, France.
authors.forename: Micka
authors.initials: M
authors.lastname: Bah
authors.affiliation: Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, IUT de BLOIS 15 rue de la chocolaterie, CS 32903, 41029 Blois Cedex, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Giovannelli
authors.affiliation: Laboratoire des Sciences des Procédés et des Matériaux, CNRS, LSPM-UPR 3407, Université Paris 13, Sorbonne Paris Cité, 99 Avenue J.B. Clément, 93430 Villetaneuse, France.
authors.forename: Frederic
authors.initials: F
authors.lastname: Schoenstein
authors.affiliation: Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, IUT de BLOIS 15 rue de la chocolaterie, CS 32903, 41029 Blois Cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Brosseau
authors.affiliation: Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, IUT de BLOIS 15 rue de la chocolaterie, CS 32903, 41029 Blois Cedex, France.
authors.forename: Jean-Robert
authors.initials: JR
authors.lastname: Deschamps
authors.affiliation: Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, IUT de BLOIS 15 rue de la chocolaterie, CS 32903, 41029 Blois Cedex, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Dorvaux
authors.affiliation: Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, IUT de BLOIS 15 rue de la chocolaterie, CS 32903, 41029 Blois Cedex, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Haumesser
authors.affiliation: Université de Montpellier, IES, CNRS, UMR 5214, F-34000 Montpellier, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Le Clezio
authors.affiliation: Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, IUT de BLOIS 15 rue de la chocolaterie, CS 32903, 41029 Blois Cedex, France. Electronic address: isabelle.laffez@univ-tours.fr.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Monot-Laffez
keywords: (K(0.5)Na(0.5))NbO(3) ceramic; Piezoelectric properties; Sintering; Ultrasonic transducer