Chiang Mai J. Sci. 2005; 32(3) : 253-260
www.science.cmu.ac.th/journal-science/josci.html
Contributed Paper
Lead-Free Piezoelectric Ceramic Based on
(Bi 1/2Na1/2)TiO 3-(Bi1/2K 1/2)TiO 3-BaTiO 3 Solid Solution
Yuji Hiruma, YYoichi
oichi Makiuchi, Rintaro Aoyagi, Hajime Nagata and TTadashi
adashi TTak
ak
enak
a*
akenak
enaka*
Faculty of Science and Technology, Tokyo University of Science,Noda, Chiba-ken 278-8510, Japan
Author for correspondence, e-mail: tadashi@ee.noda.tus.ac.jp
ABSTRACT
Piezoelectric properties of a solid solution based on three components of bismuth sodium
titanate, (Bi1/2Na1/2)TiO3 (BNT), bismuth potassium titanate, (Bi1/2K1/2)TiO3 (BKT), and barium
titanate, BaTiO3 (BT), that is, x(Bi1/2Na1/2)TiO3-y(Bi1/2K1/2)TiO3-zBaTiO3 [abbreviated to
BNBKy:z(x); y:z=2:1, 4:1 and 10:1, x+y+z=1] are studied as a lead-free piezoelectric material.
The highest electromechanical coupling factor, k33, and piezoelectric constant, d33, were 0.56
and 186 pC/N for BNBK2:1(0.878), 0.56 and 191 pC/N for BNBK4:1(0.852), and 0.52 and
180 pC/N for BNBK10:1(0.826). Nevertheless, the second phase transitions, T2, of these
compositions are about 120ºC. The T2s shift to higher temperatures with decreasing the amount
(x) of BNT content. Finally, the T2 higher than 200ºC was obtained with x ≤ 0.75, that the k33
and d33 for BNBK2:1(0.75) and BNBK4:1(0.75) were 0.44 and 116 pC/N, and 0.45 and 134
pC/N, respectively.
Keywords : antiferroelectric, barium titanate, bismuth potassium titanate, bismuth sodium
titanate, ferroelectric, lead-free piezoelectric ceramics.