Sintering and Piezoelectric Properties of Potassium Sodium Niobate Ceramics with Newly Developed Sintering Aid

Abstract

As a candidate for lead-free piezoelectric materials, (K0.5Na0.5)NbO3 (KNN)-based ceramics have been successfully synthesized via a solid state reaction. In this study, KNN-based ceramics were sintered under atmospheric pressure by adding the newly developed sintering aid (K5.4Cu1.3Ta10O29, KCT). The effects of KCT addition on the sinterability and electrical properties of the KNN ceramics were examined. The KCT addition to KNN at more than 0.38 mol% was effective to improve the sinterability of the KNN ceramics. The phase transition temperature of the KNN ceramics prepared indicated that part of KCT reacted with the KNN matrix during the sintering process. The ε r, k p, N p and Q m values of prepared KNN ceramics strongly depended upon the KCT content. The KCT addition to KNN greatly improved the Q m values (>1000) of the KNN ceramics. The Q m and k p of 0.38 mol% KCT added KNN ceramics were 1200 and 0.42, respectively. In addition, the KNN ceramics with 0.38 mol% KCT showed large field induced strain of 0.09% at 40 kV/cm, and d 33 of approximately 190 pm/V under a unipolar field from 30 to 40 kV/cm.

What Can Be Expected From Lead-Free Piezoelectric Materials?

“…Thus, KNN and BNT families may still exhibit better properties than those reported at present. 14,49,81 The domain wall contributions in PZT may account for as much as 70% of the total piezoelectric effect. These contributions may be effectively increased or decreased by donor and acceptor doping.…”

Ferroelectric Phase Transition of Lead Free (1-x)(Na0.5K0.5)NbO3-xLiNbO3Ceramics

“…In the field of piezoelectric ceramics, sodium potassium niobate ceramics with lead-free piezoelectric material have been investigated as alternative material for PZT-based ceramics [1][2][3][4][5][6][7][8][9][10][11][12][13]. Lead-free ferroelectric materials with perovskite structure have a general formula of ABO 3 .…”

“…Therefore, attempts have been made to improve the sinterability and piezoelectric properties of KNN through the addition and/or substitution of several cationic elements in the A-or B-sites [10][11][12][13] It is known that (1-x)(Na 0.5 K 0.5 )NbO 3 -xLiNbO 3 , NKN-LNx ceramics are good, lead-free piezoelectric and ferroelectric ceramics. A morphotropic phase boundary between the orthorhombic phase and the tetragonal phase of NKN-LNx was present when x was approximately 0.05 ~ 0.07 mol of LN [8].…”

Effect of washing of barium titanate powders synthesized by hydrothermal method on their sinterability and piezoelectric properties

“…Recently, many lead-free piezoelectric materials have been developed, which include Bi 0.5 (Na 1-x K x ) 0.5 TiO 3 [3], (Bi 1/2 Na 1/2 )TiO 3 -BaTiO 3 [4], (K 0.5 Na 0.5 NbO 3 [5,6], Na x K 1-x NbO 3 [7] and (K 0.5 Na 0.5 )(Nb 0.7 Ta 0.3 )O 3 [5] and so on. BT is a lead-free material.…”