Effects of Na Excess on the Preparation and Characterization of (K_0.5Na_0.5)NbO₃ Ceramics

Abstract

Lead free ceramics (K_0.5 Na_0.5+x)NbO₃ (0 ≤ x ≤ 0.3, KNN-x) were prepared by a novel method mixing perovskite structure of NaNbO₃ and KNbO₃ powders. Effects of Na excess and sintering temperatures on phase structure, microstructure and electrical properties of KNN ceramics were investigated. Result showed that the single phase perovskite structure was obtained in the KNN-0.1 ceramic sintered at 1070°C, which also showed optimized ferroelectric property with P_r = 7.16 μC/cm² and E_c = 7.95 kV/cm. The KNN-x ceramic with x = 0.2 showed optimized piezoelectric property with d₃₃ = 116 pC/N because of the homogeneous dense microstructure.

Keywords:

• Lead free ceramics
• potassium sodium niobate
• sodium excess
• electrical properties

Funding

This work was supported by the Natural Science Foundation of China under grant 51372197, the Program for New Century Excellent Talents in the University of China (NCET-11-1044), and the Key Innovation Team of Shaanxi Province (2014KCT-04), and the Doctor Startup Foundation of Xi'an University of Science and Technology (2013QDJ041).