LiNbO₃-based sol-gel composite ultrasonic transducer poled at low temperatures

Abstract

LiNbO3 (LN)-Based sol-gel composites are suitable for high-temperature ultrasonic transducer applications at 700 °C; however, poling requires high temperatures (>550 °C) and shows relatively low signal strength. To realize the polarization temperature reduction of the LN-based sol-gel composite ultrasonic transducer, alumina (AO) and strontium-doped titanium oxide (TO) were chosen as the sol-gel phase material, and LN/AO and LN/TO films were fabricated on an Inconel substrate. In each poling process, corona discharge was executed for LN/AO and LN/TO after heat treatment in the furnace at 400 °C and 200 °C, respectively. Ultrasonic measurements up to 700 °C were performed, and both transducers confirmed the reflected echoes and ultrasonic performance stability at 700 °C. In particular, LN/TO showed the highest signal strength compared to the previously developed high-temperature lead-free sol-gel composite materials, LN/BiT, Bi4Ti 3O12(BiT)/BiT, and CaBi2Ta2O9 (CBTa)/BiT.

Investigation of the crystal-oriented behavior of rare earth substituted Sr2NaNb5O15 lead-free piezoelectric materials under a high magnetic field

“…Various lead-free piezoelectric materials, such as (K,Na)NbO 3 -based, (Bi,Na)TiO 3 -based, (Sr,Ca) 2 NaNb 5 O 15 (SCNN), and bismuth layer-structured ferroelectrics have been actively studied and reported to have certain advantages over PZT. [10][11][12][13][14][15][16][17][18][19][20] The c-axis crystal-oriented SCNN ceramics have good piezoelectric properties and outstanding high-power properties compared to hard-PZT, and have also demonstrated a superior performance as an ultrasonic motor using ceramics for highpower ultrasonic devices in our previous studies. 15,16,[21][22][23][24][25][26][27][28] However, there are challenges that must be addressed to achieve mass production.…”

Thin, flexible, and biocompatible medical ultrasound array transducer using a sol–gel composite spray technique

“…We have previously developed ultrasonic transducers using the sol-gel composite spraying (SCS) method for nondestructive testing. [17][18][19][20][21][22][23][24] This technique allows the production of flexible, thermally robust sensors with broadband acoustic properties. However, previous studies did not utilize an array structure capable of generating B-mode images, nor were they sufficiently biocompatible for medical applications.…”