by Yuriko Yokouchi, Takafumi Maeda, Peter Bornmann, Tobias Hemsel, Takeshi Morita
Abstract:
We report the piezoelectric properties of CuO-doped hydrothermal (K,Na)NbO3 ceramics that can be applied as hard-type lead-free piezoelectric ceramics. To date, we have succeeded in synthesizing high-quality KNbO3 and NaNbO3 powders by the hydrothermal method, which is based on an ionic reaction at high temperature (around 210 $\,^\circ$C) and pressure. Increasing both the piezoelectric constant d and the mechanical quality factor (Qm) is important for resonance-type piezoelectric devices, such as ultrasonic motors and transformers. CuO doping into hydrothermal (K,Na)NbO3 ceramics was examined to realize hard-type lead-free piezoelectric ceramics. By doping with 1.2 mol \% CuO, Qm was increased and the dielectric loss (tan δ) was decreased to 0.5\%. The grain size was also influenced by the amount of CuO doping, which indicates that Qm is related to the density. To achieve a higher Qm value, the grain size is required to be less than 5 µm; however, excessive CuO doping leads to anomalous grain growth. Optimal piezoelectric properties were obtained for 1.2 mol \% CuO-doped (K,Na)NbO3; k31 = 0.32, d31 = -44 pC/N, Qm (radial) = 959, and tan δ= 0.5\%. These characteristics showed that CuO doping with hydrothermal powders is effective for obtaining hard-type ceramics, and the mechanical quality factor is more than ten times higher than that of nondoped hydrothermal (K,Na)NbO3 ceramics. Therefore, compared with the conventional solid-state method, we could succeed in obtaining hard-type ceramics by a simple and short process.
Reference:
Yokouchi, Y.; Maeda, T.; Bornmann, P.; Hemsel, T.; Morita, T.: Piezoelectric Properties of CuO-Doped (K,Na)NbO3 Lead-Free Ceramics Synthesized with Hydrothermal Powders. Japanese Journal of Applied Physics, volume 52, 2013.
Bibtex Entry:
@ARTICLE{Yokouchi2013,
author = {Yuriko Yokouchi AND Takafumi Maeda AND Peter Bornmann AND Tobias
Hemsel AND Takeshi Morita},
title = {Piezoelectric Properties of CuO-Doped (K,Na)NbO3 Lead-Free Ceramics
Synthesized with Hydrothermal Powders},
journal = {Japanese Journal of Applied Physics},
year = {2013},
volume = {52},
number = {7S},
abstract = {We report the piezoelectric properties of CuO-doped hydrothermal (K,Na)NbO3
ceramics that can be applied as hard-type lead-free piezoelectric
ceramics. To date, we have succeeded in synthesizing high-quality
KNbO3 and NaNbO3 powders by the hydrothermal method, which is based
on an ionic reaction at high temperature (around 210 $\,^{\circ}$C)
and pressure. Increasing both the piezoelectric constant d and the
mechanical quality factor (Qm) is important for resonance-type piezoelectric
devices, such as ultrasonic motors and transformers. CuO doping into
hydrothermal (K,Na)NbO3 ceramics was examined to realize hard-type
lead-free piezoelectric ceramics. By doping with 1.2 mol \% CuO,
Qm was increased and the dielectric loss (tan δ) was decreased to
0.5\%. The grain size was also influenced by the amount of CuO doping,
which indicates that Qm is related to the density. To achieve a higher
Qm value, the grain size is required to be less than 5 µm; however,
excessive CuO doping leads to anomalous grain growth. Optimal piezoelectric
properties were obtained for 1.2 mol \% CuO-doped (K,Na)NbO3; k31
= 0.32, d31 = -44 pC/N, Qm (radial) = 959, and tan δ= 0.5\%. These
characteristics showed that CuO doping with hydrothermal powders
is effective for obtaining hard-type ceramics, and the mechanical
quality factor is more than ten times higher than that of nondoped
hydrothermal (K,Na)NbO3 ceramics. Therefore, compared with the conventional
solid-state method, we could succeed in obtaining hard-type ceramics
by a simple and short process.},
bdsk-url-1 = {http://iopscience.iop.org/1347-4065/52/7S/07HB03/},
bdsk-url-2 = {http://dx.doi.org/10.7567/JJAP.52.07HB03},
doi = {10.7567/JJAP.52.07HB03},
file = {Yokouchi2013.pdf:Yokouchi2013.pdf:PDF},
timestamp = {2014.01.09},
url = {http://iopscience.iop.org/1347-4065/52/7S/07HB03/}
}