Observation of very high dielectric constant in Sr(Fe<inf>1-x</inf>Al<inf>x</inf>)<inf>0.5</inf>Nb<inf>0.5</inf>O<inf>3</inf> ceramics prepared by molten salt technique

Abstract

© 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Sr(Fe<inf>1-x</inf>Al<inf>x</inf>)<inf>0.5</inf>Nb<inf>0.5</inf>O<inf>3</inf> (xâ‰&0.20) powders were synthesized via the molten-sals process. Pure phase perovskite was obtained at a relatively low calcination temperature of 800 °C. The Sr(Fe;bsubesubbsubesubbsubesubbsubesubbsubesub& ceramics exhibited pure phase perovskite for x<0.20 ceramics. Dielectric measurements indicated that all ceramics showed a strong dielectric frequency dispersion, especially for the x=0.05 ceramic. Very high dielectric constants (ε>199,000 for temperatures >200 °C) were observed for the x=0.05 ceramics. Al doping enhanced the dielectric temperature stability and reduced the loss tangent. Impedance spectroscopic analysis indicated that the dielectric behaviour of the ceramics could be related to the Maxwell-Wagner polarization mechanism, since the ceramics exhibited heterogeneous conduction.