Ultrasonic transducers based on undoped lead-free (K0.5Na0.5)NbO3 ceramics

Micka Bah; Fabien Giovannelli; Frederic Schoenstein; Christophe Brosseau; Jean-Robert Deschamps; Frédéric Dorvaux; Lionel Haumesser; Emmanuel Le Clezio; Isabelle Monot-Laffez

doi:10.1016/j.ultras.2015.06.007

Ultrasonic transducers based on undoped lead-free (K0.5Na0.5)NbO3 ceramics

Ultrasonics. 2015 Dec:63:23-30. doi: 10.1016/j.ultras.2015.06.007. Epub 2015 Jun 16.

Authors

Micka Bah¹, Fabien Giovannelli¹, Frederic Schoenstein², Christophe Brosseau¹, Jean-Robert Deschamps¹, Frédéric Dorvaux¹, Lionel Haumesser¹, Emmanuel Le Clezio³, Isabelle Monot-Laffez⁴

Affiliations

¹ 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.
² 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.
³ Université de Montpellier, IES, CNRS, UMR 5214, F-34000 Montpellier, France.
⁴ 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.

PMID: 26117145
DOI: 10.1016/j.ultras.2015.06.007

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.

Keywords: (K(0.5)Na(0.5))NbO(3) ceramic; Piezoelectric properties; Sintering; Ultrasonic transducer.