Detection of magnetic environments in porous media by low-field 2D NMR relaxometry

► T1-T2 NMR correlation maps allow magnetic characterization of porous systems. ► Pore-filling water fractions with different T1/T2's are associated to susceptibility effects from Fe(III) magnetic species with different Mössbauer hyperfine fields. ► Magnetic susceptibility dilution is observed in iron-rich ceramics at long sintering temperature and time, due to partial amorphization and Al-substitution in hematite.