Microstructure and ferroelectric properties of spark plasma sintered Li substituted K0.5Na0.5NbO3 ceramics


Sen C., ALKAN B., AKIN İ. , YUCEL O. , SAHIN F. C. , Göller G.

Journal of the Ceramic Society of Japan, vol.119, no.1389, pp.355-361, 2011 (Journal Indexed in SCI Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 119 Issue: 1389
  • Publication Date: 2011
  • Doi Number: 10.2109/jcersj2.119.355
  • Title of Journal : Journal of the Ceramic Society of Japan
  • Page Numbers: pp.355-361
  • Keywords: Lead free piezoceramics, Niobates, Perovskites, Sintering, Ferroelectric properties, PIEZOELECTRIC PROPERTIES, SYSTEM

Abstract

Potassium sodium niobate (KNN) is a well known piezoelectric material and a developing candidate for replacing lead based high performance piezoceramics due to limitations of hazardous materials in electronic devices. Lithium substitution in KNN structure leads a crystal transition from orthorhombic to tetragonal symmetry at room temperature and enhances ferroelectric properties. In this study, lithium substituted KNN piezoceramics with high relative densities were prepared by spark plasma sintering (SPS). Densification, crystal structure, microstructure and ferroelectric behavior of the samples were investigated. It was observed that lithium niobate based secondary phases exist in sintered KNN ceramics. These secondary phases showed significant effects on ferroelectric properties. Maximum (Pm) and remnant (Pr) polarizations were determined as 27 and 20μC/cm2, respectively for pure KNN at the electric field of 20kV/cm. When the electric field was increased to 30 kV/cm, Pm did not change significantly, but remained below Pr. For Li substituted samples, Pr decreased with increasing Li content. © 2011 The Ceramic Society of Japan.