Influence of iron oxide substitution on the magnetic interactions in sol–gel‐derived 45S5 bioactive glass–ceramics

Abstract

AbstractMagnetic interactions in sol–gel‐derived bioactive magnetic glass–ceramics (MGCs) with compositions of (45 − x)SiO2·24.5CaO·24.5Na2O·6P2O5 xFe2O3 (2 ≤ x ≥ 15 wt.%) have been investigated using electron paramagnetic resonance (EPR), and temperature‐dependent magnetic susceptibility and magnetization (M–T) techniques. EPR spectra of the MGC samples revealed strong composition dependence in the intensity and linewidth of resonance absorptions at g ≈ 2.0 and g ≈ 4.3. EPR linewidth analysis showed the dominance of dipole–dipole interaction in MGC samples with iron oxide content ≤4 wt.% and a crossover to super‐exchange type interaction in samples with higher iron oxide content. Composition‐dependent magnetic interaction in these MGC could be related to Fe2+ and Fe3+ ion concentrations using high‐temperature magnetic susceptibility studies. Zero‐field cooled and field cooled M–T curves indicate different magnetic behavior for MGC samples with x ≤ 6 and x ≥ 8 wt.% iron oxide. Although the former show weak magnetic behavior, the latter exhibit superparamagnetic behavior which could be correlated with the percentage of magnetic phases present in each sample. These studies reveal composition‐dependent variation in dipolar and super‐exchange type interaction in the samples which could help in assessing these MGC for biomedical applications.