Magnetic clusters in ilmenite-hematite solid solutions

We report the use of high-field 57Fe Mössbauer spectroscopy to resolve the magnetic ordering of ilmenite-hematite [xFeTiO3−(1−x)Fe2O3] solid solutions with x>0.5. We find that nanometer-sized hematite clusters exist within an ilmenite-like matrix. Although both phases are antiferromagnetically ordered, the hematite clusters show ferrimagnetic behavior due to superexchange coupling with Fe2+ in ilmenite. For ilmenite-rich samples (x=0.95), the clusters are isolated and superparamagnetic. For more hematite-rich samples with x=0.80 and x=0.70, the clusters interact to form a cluster glass.