Composition Dependent Dielectric Anomaly in Na1−xKxNbO3, at x = 0.475

• Published in: Ferroelectrics 2009-11, Vol.393 (1), p.121-129
• Main Authors: Kandari, Alok Singh, Kandari, Karuna, Lingwal, Vijendra, Bourai, A. A., Panwar, N. S.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; dielectric conductivity; dielectric constant; dielectric loss; Dielectric loss and relaxation; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Ferroelectrics; morphotropic region; Permittivity (dielectric function); Physics
• ISSN: 0015-0193; 1563-5112
• DOI: 10.1080/00150190903413190

Sodium-potassium niobate (Na 1−x K x NbO 3 ) pellet samples, with x = 0.40, 0.47, 0.475, 0.48 and 0.50, were prepared by solid state reaction method. With varying composition (x), X-ray diffraction patterns show a break in the peak shifting tendency, at x = 0.475. Lattice parameters calculated from X-ray diffraction patterns show a slope change anomaly, in the a/b vs. x plot, from positive to negative, at x = 0.475. Dielectric constant, loss tangent and dielectric conductivity were found minimum for the composition with x = 0.475, among the prepared compositions, at all measured frequencies and temperatures. The observed results show a strong compositional dependence of dielectric properties, in this system. Observed minimum values of dielectric parameters may be associated with increased Na site vacancies and structural anomaly- a morphotropic type phase transition, at the composition with x = 0.475.