Properties Of Mn₁₂ Single Molecule Magnet Film And Mg-doped[(CH₃)₂NH₂][Co(HCOO)₃]

Research and development of new materials and exploration of micro-systems are important directions of current research.Single-Molecule Magnets(SMMs)have the potential to be used as information storage units in practical applications to reduce the volume of information storage materials and improve the level of information storage.At the same time,due to the peculiar quantum tunneling effect of single-molecule magnets it can be used to study quantum mechanical behavior.Metal-Organic Frameworks(MOFs)materials have a special topological structure,and the choice of metal ions and organic ligands for the preparation of metal-organic frameworks is very large,which can effectively control the pore structure and have a large specific surface area.Compared with other porous materials metal-organic frameworks have broader application prospects in a variety of fields.The research contents of this paper include two parts:the first part is the preparation and performance characterization of monomolecular magnet film;the second part is that magnesium ions are doped in[(CH₃)₂NH₂]Co(HCOO)₃ crystals,and the structure and performance of the crystals are characterized.In the preparation and performance research of monomolecular magnet films,the physical film-making methods of precipitation and volatilization have been adopted.The Mn₁₂-tBuAc film has been tested by atomic force microscopy,which shows its morphology has small fluctuation and has high surface flatness and uniformity.The results of low-temperature DC magnetic susceptibility measurement of the Mn₁₂-tBuAc film show that the molecules in the film still have blocking phenomenon at low temperature and the blocking temperature(3.6 K)is close to that of the bulk material(4.0 K).In addition,the Mn₁₂-tBuAc film has obvious hysteresis and exhibits good magnetic properties.In the preparation and performance research of magnesium ion-doped[(CH₃)₂NH₂]Co(HCOO)₃ crystals,the non-magnetic ion Mg²⁺was doped into the magnetic crystal[(CH₃)₂NH₂]Co(HCOO)₃ for the first time,and Mg²⁺doped samples[(CH₃)₂NH₂]Co_(1-x)Mg_x(HCOO)₃ were prepared.The structure and performance of samples with different doping ratios are tested.The test results show that doping does not change the crystal structure,and the unit cell parameters shift to[(CH₃)₂NH₂]Mg(HCOO)₃ in general.With the increase of doping amount,the blocking temperature decreases.With different doping ratios the area of the hysteresis loop is different,and the doping can play a certain regulatory role on the magnetism.Observed from the MT curve of[(CH₃)₂NH₂]Co_0.8Mg_0.2(HCOO)₃ crystal,the crystal may be accompanied by quantum tunneling effect during the magnetization process;finally,as the doping ratio increases,the overall level of the specific heat capacity of the sample increases,and the phase transition temperature rises.