Polarity effect of corona discharge poling for sol-gel composite-based ultrasonic transducers

Abstract

Corona discharge was produced in air atmosphere by applying positive and negative high voltage to a needle to investigate the poling effects for two kinds of sol-gel composite materials, Pb(Zr, Ti)O3(PZT)/PZT and Bi4Ti3O12 (BiT)/PZT. Concerning piezoelectric constant d33, only polarity was different. The samples poled by negative corona discharge showed superior temperature durability above certain temperatures even though no significant difference was observed regarding ultrasonic performance characteristics such as center frequency, 6 dB frequency bandwidth. When the pulse voltage supplied by pulser/receiver increased, that difference starting temperature decreased and negative corona poling effect increased. Negative corona discharge poling was effective to improve thermal durability of sol-gel composite ultrasonic transducers when normal pulser/receiver with negative excitation pulse voltage was used for measurements.

Ultrasound Sensors for Process Monitoring in Injection Moulding

“…Relative to conventional ultrasonic probes, transducers fabricated via the sol-gel technique are miniature; they can be used on curved and flat shapes; they have higher sensitivity, higher energy densities [ 48 ], a high signal-to-noise ratio (SNR) and a high thermal tolerance. Another advantage of this fabrication method is that no additional couplant is required as the ceramic powder makes a strong bond between the sol-gel film and the substrate, resulting in a crack-free film with good acoustic coupling [ 46 , 49 ].…”

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

“…However, since LN has a high Curie point, poling processes at high temperatures, at 550 °C for LN/PZT and at 900 °C for LN/BiT, were required. In addition, even though higher dielectric constants of PZT and BiT sol-gel phase than that of LN powder phase could concentrate electrical field on LN powder phase during poling, 25) signal strength of LN/PZT and LN/BiT were relatively low. Since dielectric constant of PZT and BiT sol-gel phase become maximum at Curie temperatures, it could be a problem at high temperature operation far beyond its Curie temperature.…”

Arrangement design for horizontally omnidirectional audible sound source using facing ultrasonic transducer arrays

“…Sound sources with omnidirectional characteristics have been studied for a long time and used for various purposes, such as loudspeakers for indoor voice announcements or measuring room acoustic characteristics. [1][2][3] In addition, ultrasonic transducers have been studied and implemented in a wide range of applications, such as ultrasonic sensors and parametric array speakers [4][5][6][7][8][9][10] with sharp directivity [11][12][13][14][15][16][17] owing to their flexible installation given by their size and structure. [18][19][20][21][22][23][24] In a previous study, we investigated an omnidirectional sound source using an ultrasonic transducer array.…”