Study On Structure, Magnetic Properties And Microwave Absorption Of Co - Doped Nano - Cobalt - Manganese Oxide Based On First - Principles

In recent years, the military absorbing materials and the rapid development of mobile communication devices, have caused lot of attention. Mn3O4has been used in data storage of ultrahigh magnetic resonance imaging, drug delivery, battery materials, catalysts and biological sensors. Mn3O4is a typical spinel oxide, commonly abbreviated as AB2O4(A and B respectively represent positive divalent and trivalent ion positive), contains a variety of valence compound has a complex chemical properties and physical properties (such as magnetic properties) and microwave absorption properties. Mn3O4as the magnetic dielectric spinel, complex spin states at low temperatures, resulting in a rich magnetic properties. The transition metal elements (cobalt, iron, manganese) manganese oxide doping has been extensively studied in the past few years,Pure single Mn3O4component of the microwave absorption properties is very weak, so we dopant Co into pure Mn3O4to synthesize a series of different proportions of cobalt and manganese oxides. The preparation, characterization and the magnetic and microwave absorption properties are studied, the first-principles density of states of simulation are studied to further illustrate its internal mechanism. Specifically, the main contents of this paper include the following aspects:(1) Synthesis of a series of (Mn1.xCox)3O4nanoparticles through a low-temperature thermal decomposition method for preparing a particle size less than6-lOnm. With the increase in the content of Co, the lattice constant of the product change. TEM and EELS spectra further proof of the doped cobalt-substituted manganese atoms. Its magnetic properties are measurement by a superconducting quantum interference device (SQUID), we found that the temperature gradually decreasing trend with the increase in doping amount, and the hysteresis loops show that at low temperatures the magnetic properties of the sample with cobalt doping elements are closely linked.(2) microwave absorption properties of (Mn1-xCox)3O4become stronger with the increase of cobalt doping, thickness of4mm, for x=0.5, the reflection loss can achieve to-24.5dB.The further calculation results explain the coupling between3d states of Co and Mn,,resulting in the splitting of the spin polarization becomes large, leading to a shift of the microwave absorption properties.