Eur. Phys. J. B (2012) 85: 215
https://doi.org/10.1140/epjb/e2012-21000-1

Regular Article

Dielectric properties and relaxation phenomena in the diffuse ferroelectric phase transition in K₃Li₂Nb₅O₁₅ ceramic

¹ LMCN, F.S.T.G Université Cadi Ayyad, avenue Prince Moulay Abdellah, B.P. 511, 40000 Marrakech, Maroc
² LPMC, Université de Picardie, 33, rue Saint-Leu, 80039 Amiens Cedex, France
³ LPMC, F.S.J., Université Chouaib Doukkali, Route Ben Maachou, 24000 El Jadida, Maroc

^a e-mail: yaovi.gagou@u-picardie.fr

Received: 7 December 2011
Received in final form: 14 April 2012
Published online: 25 June 2012

Abstract

Structural and dielectric properties of Potassium Lithium Niobate polycrystalline ceramic K₃Li₂Nb₅O₁₅ (KLN), having the tetragonal tungsten bronze (TTB) – type structure are studied in the temperature interval 50−550 °C. Special emphasis is given to the diffuse phase transition occurring around 440 °C. Space charge polarization, relaxation phenomena and free charge conductivity have been elucidated using impedance spectroscopy technique. Argand plots have revealed a non Debye and polydispersive type relaxation. In paraelectric phase the Arrhenius activation energy E_τ = 0.533 eV was determined. The structural and dielectric results are compared with two others TTB compounds derived from KLN family: Pb_1.85K_1.15Li_0.15Nb₅O₁₅ (PKLN) and GdK₂Nb₅O₁₅ (GKN).