Processing of Piezoelectric (Li,Na,K)NbO₃ Porous Ceramics and (Li,Na,K)NbO₃/KNbO₃ Composites

Abstract

Porous Li 0:06 (Na 0:5 K 0:5 ) 0:94 NbO 3 (LNKN-6) ceramics with different pore volumes have been prepared using preceramic powder and phenol resin fiber (KynolÔ) as a pore former. It was confirmed that the porous ceramics synthesized by the ''twostage firing method'' suppressed the loss of alkali elements from the porous body during heat treatment. The porous LNKN-6 ceramics were then converted to LNKN-6/KNbO 3 composites through soaking and heat treatment using a sol-gel precursor source composed of KNbO 3 to form 3 -3-type composites. The microstructure, dielectric, and piezoelectric properties of the porous LNKN-6 ceramics and LNKN-6/KNbO 3 composites were characterized and compared. The LNKN-6/KNbO 3 composites had a hollow structure whose pores in the region near the surface were filled and coated with KNbO 3 precipitates; however, a large amount of residual air was trapped in the pores inside the composites. As a result, the LNKN-6/KNbO 3 composites fabricated using 30 vol % KynolÔ showed an enhanced piezoelectric voltage output coefficient (g 33 ) of 63:0 Â 10 À3 VÁm/N, compared with monolithic LNKN-6 ceramics having a g 33 of 30:2 Â 10 À3 VÁm/N.

Effect of sintering condition and V-doping on the piezoelectric properties of BaTiO₃–Bi(Mg_1/2Ti_1/2)O₃–BiFeO₃ ceramics

“…Gold electrodes were formed on both surfaces by sputtering, and the samples were heated at 300°C for 10 min to improve the adhesion. The samples were sawed into a size of 4 © 1.5 © 0.4 mm 3 . The room temperature dielectric constant and loss were measured at frequencies from 40 Hz to 1 MHz using an impedance analyzer (HP4294A, Agilent).…”

“…15) The motion of the fine domains by the electric field was observed, which was suggested to lead the large piezoelectric properties. 16) Since nano-sized domains are also reported for solid-solutions of relaxors Pb(Zn 1/3 Nb 2/3 )O 3 and Pb(Mg 1/3 Nb 2/3 )O 3 and ferroelectric PbTiO 3 with large piezoelectric properties, 17),18) they may be associated with the increased piezoelectric response of PZT at MPB.…”

Sintering and piezoelectric properties of K0.5Na0.5NbO3 glass microspheres

“…Therefore, they are not shown in this paper. In fact, Hikita [17] and Kakimoto [19] reported opposite results about the piezoelectric constant (d 33 ) in relation to the porosity. Hikita [17] found that d 33 slightly increases with the porosity content while Kakimoto [19] found that d 33 decreases with the porosity content.…”

“…In fact, Hikita [17] and Kakimoto [19] reported opposite results about the piezoelectric constant (d 33 ) in relation to the porosity. Hikita [17] found that d 33 slightly increases with the porosity content while Kakimoto [19] found that d 33 decreases with the porosity content. As a result, the big difference of d 33 and 33 / o for the two hipped samples may belong to one or two of the following reasons: the relative density difference and unsaturated polarization.…”

Influence of Cell Size on Mechanical and Piezoelectric Properties of PZT and LNKN Ceramic Foams

“…The values obtained for dense PZT reference samples were d bulk 33 ¼ 325 pCN À1 , d bulk 31 ¼À140 pCN À1 , and relative permittivity e bulk r ¼ 1195 [25] and for dense LNKN-six reference samples were d bulk 33 ¼ 195 pCN À1 , d bulk 31 ¼-7.36 pCN À1 , and relative permittivity e bulk r ¼ 740, [26] respectively. Polarization was carried out with 3 kV mm À1 at 150 C (PZT) and at 80 C (LNKN-6) in a silicone oil bath for 1 h. The relative permittivity e r and the longitudinal piezoelectric coefficients d 33 and d 31 were measured by Berlincount method (Piezo-Meter PM 300, Piezo Test, London, England).…”