Magnetic Properties Of Oxalate Bridged Bimetallic Molecular Magnets

Molecular magnets is through organic, organic metals, coordination chemistry and polymer chemistry synthesis of magnetic materials at low temperatures. Molecule magnets in the design and synthesis, involving chemistry, physics, materials and life sciences and many other areas, has become one of the hot topic in the physics and chemistry at the forefront. Oxalate bridged ligand has good magnetic interaction capacity between metal ions so that molecular magnets play an important role due to their special structure and outstanding magnetic properties in the magnetic field.In this paper, the structural characterization, magnetic measurements and M?ssbauer measurements are performed to study microstructure, magnetic coupling mechanism and the magnetic properties and so on for oxalate bridged bimetallic molecular magnets. AC magnetic measurements is used to study phase transition at low temperatures in the complex {[N(n-C H ) ][CoFe(C O ) ]}n. M?ssbauer measurements is chosed to study and analyze the microscopic characteristics for molecular magnets {[N(n-C H ) ][FeFe(C O ) ]}n. Some important results are obtained as following:1. The results of AC magnetic measurements are analyzed for the oxalate bridged bimetallic complex {[N(n-C4H9)4][CoFe(C2O4)3]}n at low temperatures. The results demenstrated the two phases coexistence at low temperatures in the complex. We observed the appearence of the temperature point of spin-glass phase transition and magnetic phase transition under the zero-field-cooled AC magnetic measurements. The phenomenon indicated the coexistence of the spin glass phase and ferrimagnetic ordered phase at low temperatures in this system. Also, it was further explanation with spin glass state theory.2. M?ssbauer spectroscopy theory was used to investigate the measuremental spectrum results for the complex {[N(n-C4H9)4][FeFe(C2O4)3]}n, the spectrum demenstrate the mixed valency character and magnetic coupling interaction between FeII and FeIII ions and the phenomenon of spontaneous magnetization between FeII and FeIII sublattices. The magnetic splitting spectrum are observed below 50 K in M?ssbauer spectrum. Magnetic splitting spectrum indicate the presence of the long-range magnetic ordering behavior in the complex. At the same time, the hyperfine field parameters show that the dependent of the hyperfine field and the spontaneous magnetization and that of the spontaneous magnetization and temperature in the FeII and FeIII sublattices. The spectral diversification and the structural characteristics suggest the adjacent metallic magnetic ions exist the anti-ferromagnetic coupling interaction in the complex. Secondly, the spectrum indicate the electronic state of irons is high-spin state Fe²⁺(S=2)-ox-Fe³⁺(S=5/2) at 60 K.Finally, this paper summarizes the research work and further prospects the potential research value and the wider application future on molecular magnets.