Microstructural, dielectric, impedance and electric modulus studies on vanadium-doped and pure strontium bismuth niobate (SrBi2Nb2O9) ceramics

摘要

SrBi2Nb2O9 (SBN) and SrBi2(Nb0.9V0.1)(2)O-9 (SBVN) ceramics were fabricated from the powders consisting of mu m sized grains, obtained via the solid state reaction route. V2O5 was found to be an effective microstructure modifier and grain growth truncator for SBN ceramics. X-ray structural studies carried out on SBVN ceramics confirmed the existence of preferential orientation (c-planes) of the grains. V2O5 addition has substantially improved the sinterability of SBN and enabled to achieve high density (95%) which was otherwise difficult in the case of pure SBN. The dielectric properties of SBN ceramics were significantly enhanced by the partial replacement of Nb ions by pentavalent vanadium ions. The complex impedance diagrams of dense SBVN ceramics exhibited only one semicircle indicating a significant contribution from the grains. In contrast, the impedance plots for the porous (density 88%) SBN ceramics show an additional low-frequency semicircle which was attributed to the blocker (pore) size effects. The dielectric behavior of SBN and SBVN ceramics was rationalized using the impedance and modulus data. (C) 2005 Springer Science + Business Media, Inc.