Synthesis of lead-free piezoelectric powders by ultrasonic-assisted hydrothermal method and properties of sintered (K_0.48Na_0.52)NBO₃ ceramics

Abstract

(K,Na)NbO3 ceramics have attracted much attention as lead-free piezoelectric materials with high piezoelectric properties. High-quality (K,Na)NbO3 ceramics can be sintered using KNbO3 and NaNbO3 powders synthesized by a hydrothermal method. In this study, to enhance the quality factor of the ceramics, high-power ultrasonic irradiation was employed during the hydrothermal method, which led to a reduction in the particle size of the resultant powders.

Thick KNbO₃ films deposited by ultrasonic-assisted hydrothermal method

“…Thus, the ultrasonic wave penetrates the water and the Teflon foil, and reaches the solution with little attenuation because the acoustic impedance of water and Teflon is almost the same. With this design, contamination from the tip of the transducer can be prevented [11]. 2.2.…”

“…In this study, thick potassium niobate (KNbO 3 ) films were investigated, which are required for medical transducers and micro actuators. To fabricate such films, we introduced an ultrasonic-assisted hydrothermal method [7][8][9][10][11].…”

“…However, it has a long reaction time and repeated deposition has been required for thicker films [12,13]. To overcome this problem, we developed an ultrasonic-assisted hydrothermal method [7][8][9][10][11] to obtain thicker films. Upon ultrasonic irradiation, cavitation is generated, which is effective for promoting the hydrothermal reaction [8].…”

Optimum reaction conditions for lead zirconate titanate thick film deposition by ultrasound-assisted hydrothermal method

“…To promote hydrothermal reactions, we proposed an ultrasonic-assisted hydrothermal method, [21][22][23][24][25] which accelerates chemical reactions by the agitation effect and the cavitation 26) generated by an ultrasonic transducer. A 7.5-µmthick PZT film could be deposited on a titanium substrate by the ultrasonic-assisted hydrothermal method, which is 2.5 times thicker than that deposited by the conventional hydrothermal method.…”