Dielectric and Electromechanical Properties of (K,Na)NbO₃ Ceramics Prepared by Hot Isostatic Pressing

Abstract

Lead-free piezoelectric sodium potassium niobate ((K,Na)NbO₃; KNN) ceramics with various grain sizes were prepared by hot isostatic pressing (HIP) and post-annealing. Their dielectric and electromechanical properties were then investigated. The average grain sizes of the ceramics were controlled by changing the post-annealing temperature. KNN ceramics obtained by HIP at 800°C without post-annealing with an average grain size of 0.34 μm exhibited a dielectric constant of 149, field-induced strain of 0.006% under 20kV/cm, and the piezoelectric d₃₃ coefficient of 40pC/N by d₃₃ meter measurement.

• Keywords Sodium potassium niobate
• hot isostatic pressing
• lead-free
• grain size

Funding

This study was supported in part by JSAP KAKENHI Grant Number.26420684 and a GRENE (Green network of excellence) project grant from the ministry of education, culture, sports, science, and technology, Japan, as well as a grant from the Kato Science Foundation.