CoMn2O4 spinel from a MOF: Synthesis, structure and magnetic studies

摘要

A hydrothermal reaction of Mn(OAc)_2·4H_2O, Co(OAc)_2·4H_2O and 1,2,4 benzenetricarboxylic acid at 220 °C for 24 h gives rise to a mixed metal MOF compound, [CoMn _2{C_6H_3(COO)_3}_2], I. The structure is formed by the connectivity between octahedral CoO_6 and trigonal prism MnO_6 units connected through their vertices forming a Kagome layer, which are pillared by the trimellitate. Magnetic susceptibility studies on the MOF compound indicate a canted anti-ferromagnetic behavior, due to the large antisymmetric DM interaction between the M~(2+) ions (M = Mn, Co). Thermal decomposition studies indicate that the MOF compound forms a tetragonal mixed-metal spinel phase, CoMn_2O_4, with particle sizes in the nano regime at 400 °C. The particle size of the CoMn_2O_4 can be controlled by varying the decomposition temperature of the parent MOF compound. Magnetic studies of the CoMn _2O_4 compound suggests that the coercivity and the ferrimagnetic ordering temperatures are dependent on the particle size.