Electrical conductivity and dielectric properties of Sr doped M-type barium hexaferrite BaFe12O19†

Abstract

The Raman results showed that the intensity of the resonance band remains unchanged in Ba 1 xSrxFe12 O 19 compared to the undoped compound (x ¼ 0) indicating that the polarizability did not change during the vibrations. The particle sizes, observed by TEM, are reduced from 228 nm to 176 nm with doping. Electrical conductance measurements show that all samples present semiconductor-like behaviors. The Maxwell–Wagner.model explains why the alternating electrical conductivity of the samples doped with Sr is lower ompared to that of the undo-ped sample. The Correlated Barrier Hopping (CBH) modeldominates the conduction process for the BaFe12 O 19 sample, whereas the No overlapping Small Polaron Tunneling (NSPT) model dominates the conduction process for the Ba0.5 Sr 0.5 - Fe12 O 19 sample. For SrFe 12 O19 the conduction is dominated by the NSPT model at temperatures below 240 K and by the CBH model above 240 K. The BaFe12 O19 compound exhibits a giant dielectric constant (30) whose values reached 10 4 at low frequencies. This value is reduced to 150 in the Sr-doped hexaferrite.