Sinterability and Piezoelectric Properties of (K,Na)NbO3 Ceramics with Novel Sintering Aid

概要

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Dense (K,Na)NbO3 (KNN)-based ceramics were developed by optimizing the sintering conditions with newly developed K4CuNb8O23 (KCN) as a sintering aid. The sinterability and electrical properties of KNN ceramics were investigated as a function of KCN concentration. The density of KNN ceramics increased monotonically with increasing the KCN contents, and reached the highest value of 4.40 g/cm3 with the addition of 0.5 mol% KCN. This is due to the formation of liquid phase, which significantly promotes the densification of KNN ceramics. The Curie temperature ($T_{\text{c}}$) of pure KNN ceramics was 420°C and decreased with increasing the KCN content. With the addition of 0.5 mol% KCN, planar mode electromechanical coupling factor ($k_{\text{p}}$) and mechanical quality factor ($Q_{\text{m}}$) of KNN ceramics also reached the highest values of 0.39 and 1200, respectively. The KNN ceramics prepared with 0.5 mol% KCN exhibited a large field-induced strain of 0.09% at 40 kV/cm and the piezoelectric constant $d_{33}$ of 180 pm/V.
2004-10-15