Abstract
The general expression for the magnetic-field-induced quadrupole splitting is derived for dn transition metal ions in a crystal field of octahedral symmetry. The effective magnetic field may arise from either an applied field or a molecular field. Bonding effects are also treated. The temperature dependence of the quadrupole splitting ΔEQ induced by an applied magnetic field is calculated for 57Fe high-spin ferrous and low-spin ferric compounds where the ions are in crystal fields of octahedral symmetry.