Low‐Temperature Sintering and Piezoelectric Properties of <scp> <scp>CuO</scp> </scp> ‐Added <scp> <scp>KNbO</scp> </scp> ₃ Ceramics

Abstract

Dielectric and piezoelectric properties of CuO ‐added KNbO 3 ( KN ) ceramics were investigated. The CuO reacted with the Nb 2 O 5 , formed a CuO – Nb 2 O 5 ‐related liquid phase during the sintering, and assisted the densification of the KN ceramics at low temperatures. Moreover, some of the Cu 2+ ions replaced the Nb 5+ ions in the matrix and behaved as a hardener. The dielectric and piezoelectric properties of the KN ceramics were considerably influenced by the relative density. The 1.0 mol% CuO ‐added KN ceramic sintered at 960°C for 1.0 h, which showed a maximum relative density, exhibited a high phase angle of 86.9°, P r of 14.8 μC/cm 2 , and E c of 1.8 kV/mm. This specimen also exhibited good dielectric and piezoelectric properties: ε T 33 / ε o of 364, d 33 of 122 pC/N, k p of 0.29, and Q m of 611.