Fabrication of lead-free piezoelectric (Na_0.5K_0.5)NbO₃ ceramics by a modified solid-state reaction method

Abstract

Sodium potassium niobate, (Na(0.5)K(0.5))NbO(3), fine powder has been successfully synthesized at the low temperature of 550 degrees C through a modified solid-state reaction method, in which urea [CO(NH(2))(2)] plays an important role. High-density (Na(0.5)K(0.5))NbO(3) ceramics could be obtained by conventional sintering of the synthesized (Na(0.5)K(0.5))NbO(3) fine powder with the addition of 0.03 mol% Co(3)O(4) as a sintering additive. The crystal structure, microstructure, and dielectric and piezoelectric properties were characterized. The (Na(0.5)K(0.5))NbO(3) ceramic showed a comparatively saturated P-E hysteresis loop. The (Na(0.5)K(0.5))NbO(3) ceramic also displayed piezoelectricity with a piezoelectric constant d(33) of 126 pC/N and a planar electromechanical coupling factor k(p) of 33%.

Preparation of needle-like NaNbO3 by molten NaOH method

“…5(b). These peaks are attributed to Na 7 (H 3 O)-Nb 6 O 19 , which corresponds to Na 8¹x (H 3 O) x Nb 6 O 19 ·nH 2 O with x = 1.0 and n = 0.…”

Piezoelectric properties of (K0.474Na0.474Li0.052)(Nb0.948Sb0.052)O3-Co2O3 lead-free ceramics

“…20) Moreover, cobalt oxide was used as an additive to modify the electrical properties of BNT-based systems. 21), 22) Therefore, it is of great interest to study the sinter-ability and piezoelectric properties of KNN-based ceramics with an addition of cobalt oxide.…”

Fabrication of (K,Na)NbO<inf>3</inf> thin films on Si substrate by pulsed laser deposition

“…The ε r (640) and tanδ (0.06) values of the NKN film deposited at 50 mTorr are comparable to those of the 001-orientated NKN film deposited on Si substrate with ε r of 598 and tanδ of 0.08, and the 001-orientated NKN film deposited on (001)STO substrate by RF Magnetron Sputtering with ε r of 452 and tanδ of 0.017 [6,14]. The ε r and tanδ of the NKN ceramic (Co 3 O 4 -doped) were also 426 and 0.03 [13]. This is because the orientation direction of the NKN film was perpendicular to the polarization direction.However, the 001orientated NKN film showed a smaller ε r value than that of the 111-orientated NKN films in this study.…”

“…We characterized the crystallographic structure, chemical composition and electrical properties of the NKN films.II. EXPERIMENTAL PROCEDUREAn NKN ceramic target was prepared by a combination of a modified solid-state reaction[13] and conventional sintering. Potassium oxalate [K 2 C 2 O 4 ] (99.0%), sodium oxalate [Na 2 C 2 O 4 ] (99.0%), niobium oxide [Nb 2 O 5 ] (99.9%) and urea [CO(NH 2 ) 2] (99.0%) as starting materials were mixed for 1.5 h using an agate mortar and pestle.…”