Title of article :
Effect of hafnium-incorporation on the microstructure and dielectric properties of cobalt ferrite ceramics
Author/Authors :
S. Wells، نويسنده , , C.V. Ramana، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2013
Abstract :
The effect of hafnium (Hf) incorporation on the crystal structure, surface morphology, chemical composition and dielectric properties of cobalt ferrite (CoFe2O4) is reported. Hafnium incorporated Co-ferrite (CoFe2−xHfxO4) ceramics were prepared by varying the Hf concentration in the range of x=0.0–0.2. X-ray diffraction (XRD) studies indicate that the CoFe2−xHfxO4 ceramics crystallize in inverse spinel change to structure similar to that of pure CoFe2O4. Hafnium incorporation induces lattice expansion leading to increased lattice constant from 8.374 Å for pure CoFe2O4 to 8.391 Å for the highest Hf concentration (x=0.2) in CoFe2−xHfxO4. Dielectric constant of CoFe2−xHfxO4 ceramics is also enhanced compared to pure CoFe2O4 due to the lattice distortion upon Hf incorporation. Improved dielectric properties of CoFe2−xHfxO4 ceramics compared to pure CoFe2O4 is attributed to the lattice distortion due to larger Hf-ions substituting for smaller Fe-ions associated structural changes with increased Hf concentration. Frequency variation of the dielectric constant shows the dispersion that can be modeled with a modified Debyeʹs function, which considers the possibility of more than one ion, contributing to the relaxation.
Keywords :
C. Dielectric properties , Cobalt Ferrite , crystal structure , Hafnium incorporation , lattice expansion
Journal title :
Ceramics International
Journal title :
Ceramics International