Synthesis and magnetic properties of Mg0.2Cr1.8−xFexO3 nanoparticles

► Prepared Mg0.2Cr1.8−xFe2O3 compounds by hydrothermal process. ► Anomalous variation of magnetization in low fields has been observed. ► The oxides exhibit exchange bias effects which appear to be sensitive to grain sizes. ► Samples with larger grains show more enhanced exchange bias effect. ► Results from 400 K to 10 K show evidence of strong antiferromagnetic interactions in the compounds.