Defect chemistry of a high-k 'Y5V' (Ba0.95Eu0.05)TiO3 ceramic

The influence of the sintering temperature (T-g) on the structure, dielectric and valence-state properties of (Ba1-xEux)TiO3 (x=0.05) ceramics was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), Raman spectroscopy, and dielectric temperature measurements. An increase in T-g can increase the solubility limit of Eu in BaTiO3. When the T-s was increased to 1450 degrees C, a high-k 'Y5V' (epsilon'(RT)=8500) ceramic (C-BE5T) with a single-phase cubic structure was obtained. The dielectric peak shifted rapidly toward lower temperatures with increasing T-s at a rate of -0.46 degrees C/K. A symmetric (200) XRD peak, exaggerated grain growth (5.6 mu m), a mixed valence of Eu2+/Eu3+, an asymmetric main Raman band at 2494 cm(-1) and a weak sharp band at 1516 cm(-1) in the high-wavenumber region are characteristics of cubic symmetry of C-BEST. The formation of a solid solution of C-BEST and defect chemistry are discussed. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.