Piezoelectric properties of (K0.5Na0.5)(Nb1−xTax)O3−K5.4CuTa10O29 ceramics

TLDR

KNNT-based ceramics were synthesized via a solid‑state reaction. The study sintered KNNT ceramics at atmospheric pressure by adding 0.38 mol % K5.4Cu1.3Ta10O29 as a sintering aid. The authors examined the quantitative effects of Ta on the electrical properties of (K0.5Na0.5)(Nb1−xTax)O3–K5.4Cu1.3Ta10O29 ceramics. Adding 0.38 mol % K5.4Cu1.3Ta10O29 yields KNNT ceramics with hard piezoelectric behavior (Qm = 1300, tan δ = 0.4 %) and Ta substitution tunes the material to soft characteristics, producing a large electrostrictive effect and enhancing kp, εr, strain, and d33, with the (K0.5Na0.5)(Nb0.7Ta0.3)O3 composition achieving a maximum strain of 0.11 % at 40 kV cm⁻¹ and d33 of 270 pm V⁻¹, comparable to hard Pb(Zr,Ti)O3 ceramics.

Abstract

( K 0.5 Na 0.5 ) ( Nb 1 − x Ta x ) O 3 (KNNT)-based ceramics have been synthesized via a solid-state reaction. In this study, KNNT-based ceramics were sintered at atmospheric pressure by adding small amounts of sintering aid [0.38mol% K5.4Cu1.3Ta10O29]. The (K0.5Na0.5)NbO3 (KNN) ceramics which synthesized by using the K5.4Cu1.3Ta10O29 showed “hard” piezoelectric characteristics such as a high mechanical quality factor (Qm=1300) and low tanδ (0.4%). The quantitative effects of Ta on the electrical properties of (K0.5Na0.5)(Nb1−xTax)O3–K5.4Cu1.3Ta10O29 ceramics were also examined. Ta substitution provides “soft” piezoelectric characteristics and a large electrostrictive effect for KNN, which resulted in an improvement in kp, εr, strain, and d33 of KNNT ceramics depending upon the Ta content. Especially, (K0.5Na0.5)(Nb0.7Ta0.3)O3 showed the maximum strain and d33 values of 0.11% (at 40kV∕cm) and 270pm∕V (at 30–40kV∕cm), respectively. This strain level is comparable to that of hard Pb(Zr,Ti)O3 ceramics.