Preparation and simulation of lead free NBBT/epoxy 1–3 piezoelectric composites for high frequency medical ultrasound. (December 2022) - Zhou, Xun
Abstract: This paper presents the modeling and fabrication of the (1-x)Na0.5 Bi0.5 TiO3 -xBaTiO3 single crystal/epoxy 1–3 piezoelectric composite (NBBT 1–3 composite) with large electromechanical coupling factor ( k t ) for high frequency ultrasonic transducers. The NBBT 1–3 composite has been modeled by performing the finite element method using the COMSOL Multiphysics software. The parameters related to NBBT crystal are refined in the modeling process and the simulation results agree well with that of the experiment. The composite has been fabricated by the dice-and-fill method with a pitch of 12 μm. The measured resonance frequency, antiresonance frequency and electromechanical coupling factor ( k t ) with the values of 31.88 MHz, 43.16 MHz and 71.06% are obtained, respectively. The excellent performance of NBBT/epoxy 1–3 piezoelectric composite is comparable to that of lead-based Pb(Mg1/3 Nb2/3 )O3 –PbTiO3 /epoxy 1–3 piezoelectric composites. The excellent performance and the lead-free advantages make the NBBT/epoxy 1–3 piezoelectric composites quite attractive in high frequency medical ultrasound applications especially within the human body like intravascular ultrasound imaging (IVUS). Graphical abstract: (a) Impedance spectrum and phase angle of experimentally obtained NBBT/epoxy 1–3 piezoelectric composites with a thickness of 50 μm; (b) Impedance spectrum and phase angle with a thickness of 50 μm for NBBT/epoxy 1–3 piezoelectric composite simulated by COMSOL; (c) The coupling mode at 40.00 MHz; (d) Impedance spectrum and phase angle with a thickness of 35 μm for NBBT/epoxy 1–3 piezoelectric composite simulated by COMSOL. Image 1 Highlights: 1–3 composites based on high-performance lead-free piezoelectric crystal NBBT are reported. The resonant and anti-resonant frequencies of the composites are as high as 31.88 MHz and 43.16 MHz, respectively. The electromechanical coupling factor of the composite material reaches 71.06%. The simulation results of COMSOL software are in good agreement with the experimental data.