Magnetic Properties Of Molecular Magnets Based On The Oxalate

Molecule-based magnets which molecules or ions act as a building blocks is a new type of soft magnetic material. Molecule-based materials have a three-dimensional structure of magnetic ordering below transition temperature. Its magnetic internation derived from intermolecular interactions. In recent years, the research of materials science has become the focus of chemists and physicists, It was prepared to use synthesis of organic or inorganic chemical. As a magnetic material, molecular ferromagnet is a magnetic physical characteristics of the molecule-based materials. Certainly, molecular magnetic materials is the characteristics of a small bulk, the relative density light, the structural diversification, the easy-to-composite processing. It was related to chemistry, physics, material, life sciences, and many other domain, formed a new field of study. It may become a production materials of space vehicle, microwave absorbing stealth, electro-optical applications and so on. Major study is possessed of materials of magnetic, magnetic and optical, electromagnetic shielding and information storage. We believe that the study of molecular magnetism lies the stage of the theoretical exploration yet.In this paper, we mainly study that focus on is the root of oxalic acid as a bridging ligand of the magnetic properties of molecular magnets.The oxalate group has been shown to be an excellent bridging ligand in supporting the magnetic exchange interaction. Symmetry and anti-symmetry of oxalate show the rich features nature of the complex,the length of oxalate ligand is small. This increases the magnetic exchange, magnet and Curie point strongly,It is very practical value of the bridging ligand. By Mossbauer spectroscopy measurements, We can reach samples of the hyperfine magnetic field, spin state, metal ion valence state and other properties.During the completion of the course paper, we have reached the following some key findings1. The temperature dependence of the molar magnetic susceptibility and magnetization of NBu4Zn(Ⅱ)nFe(Ⅱ)1-n[Fe(Ⅲ)(ox)3 compounds with 0< n≤0.1 was studied in the temperature range of 2-290K. In the FC mode, the compounds with 0≤n≤0.08 showed two temperature compensation points on temperature scale in 32-41.5K temperature range. Multiple magnetic-pole reversals were observed in the material. We can explain the observed multiple magnetic-pole reversals in terms of a combination of molecular-field theory and the coercive field. n≥0.1, the temperature compensation point disappeared. At the same time, we found spin glass state below 35K range.2. Some materials of general molecular formula NBu4FeⅡxMnⅡ1-x [FeⅢ(OX) 3] were synthesized, variation of magnetic phase transition temperature Tc of series of compounds illustrates the interaction of magnetic doping in the material. At low temperatures series of compounds show a strong anti-ferromagnetic and appears weaker spin-sloped phenomenon. Results of magnetic measurement show that the anti-ferromagnetic super-exchange interaction between Fe (Ⅲ) (d5, e2gt32g, S= 5/2) and Mn (II) (d5, e2gt32g, S = 5/2) and the anti-ferromagnetic super-exchange interaction between Fe (Ⅲ) (d5, e2gt32g, S = 5/2) and Fe (Ⅱ)(d6,e2gt42g,S= 2).3.{[N (n-C4H9) 4] [FeFe (C204) 3]}n was synthesized, we study it with MOssbauer spectrum in the room temperature. It proved that the compound existed high-spin Fe (Ⅲ) (d5, e2gt32g, S= 5 /2), high-spin Fe (II) (d6, e2gt42g, S= 2) and low spin Fe (II) (d6, t62g, S= 0).Eventually, this article summarizes the work and looked to the future of molecular magnets oxalate research direction...