Study And Application On The Magnetic Properties Of Garnet Ferrite Nano-materials Doped With Rare-earth Ions

The garnet iron ferrite nano-materials as an important ferrimagnetic materials, with superior magnetic properties, magneto-optical properties and dielectric properties of widely used in magneto-optical recording, microwave materials, spin magnetic materials and other fields. In addition, the magnetism structure of the garnet iron ferrite is simple, its only contains the magnetic ions of Fe³⁺ as S-state, and it has therefore become the basis materials to study the magnetic theoretical. In this paper, we focused on the two aspects of the theory and the application of the magnetic properties of the garnet iron ferrite nano-materials.As the garnet iron ferrite (YIG) in the microwave applications demonstrate the outstanding characteristics, we are in order to improve the performance of applications development. We have chosen different ions (Ce, Er, Bi) to the substituent in the garnet iron ferrite nano-materials, by regulating the type and ion content of the composite material to control saturation magnetization intensity, and to satisfy the needs of different practical applications requirements. Firstly, the pure Y₃Fe₅O₁₂ (YIG) powder materials through the sol-gel method were synthesized. The size of the materials is in the nano-size, scope is in the 35 to 57 nm. saturation magnetization (Ms) is 26.7 emu / g. Single-phase material show with the garnet structure. On the material form garnet structure of single-phase synthesis conditions, we have optimized. On this basis, we have synthesized Y_3-xBi_xFe₅O₁₂() system, Y_3-xEr_xFe₅O₁₂ and Y_3-xCe_xFe₅O₁₂ system samples, respectively. The largest substituent of the Bi³⁺ and Ce³⁺ ions is 1.3 and 0.1 respectively. The experimental results show that, the magnetization of the Y_3-xBi_xFe₅O₁₂ system single-phase samples were decrease with increase of the Bi³⁺ ions concentrate x. The magnetization of the Y_3-xEr_xFe₅O₁₂ system samples were decrease with increase of the Er³⁺ ion concentrate x, the cercibvity increase with the increase of the x, the remanence did not change significantly with increase of the x. The saturation magnetization of the Y_2.9Ce_0.1Fe₅O₁₂ samples is 28.0 emu /g, it is higher than that of Y₃Fe₅O₁₂ samples.In addition, as ferrite garnet in the field of magneto-optical memory applications, in order to meet the magnetic stability, saturation magnetization Ms appropriate to the range, translucent has a good requests, we have designed and synthesized a series of rare-earth doped double to a new type of nano-composite materials Y_2.9-xCe_0.1RE_xFe₅O₁₂ (RE = Dy, Gd, Sm, Nd, La). These new composite materials are in the nanometer scale, which effectively reduces the volume of material which is heated, and also enhance the transparency of the material. The introduction of cerium ions effectively enhance the magneto-optical properties, and incorporate another kind of rare earth ions to adjust the saturation magnetization. A series of new nano-composite materials are in the nano-size, scope in the 39 to 65 nm, and grain size increased with the increasing calcination temperature. Through the introduction of suitable light rare earth ions (Nd³⁺) we can increase the saturation magnetization of new nano-composite materials Y_2.9-xCe_0.1RE_xFe₅O₁₂, through the introduction of heavy rare earth ions (Gd³⁺, Dy³⁺) and non-magnetic properties of rare earth ions (La³⁺) can reduce the saturation magnetization of materials. The saturation magnetization of new dual-compound Y_2.9-xCe_0.1RE_xFe₅O₁₂ (RE = Dy, Gd, Sm, Nd, La) nano-materials decided by the rare-earth ions in the incorporation of electronic and magnetic coupling arrangement, and also it is influenced by the change of the crystal structure. These three factors together determine the magnitude of saturation magnetization of Y_2.9-xCe_0.1RE_xFe₅O₁₂ (RE = Dy, Gd, Sm, Nd, La) nano-composites. In addition, in order to study the tendency of site occupancynion, the effect of magnetic moment arrangement coupling and anisotropy on the saturation magnetization. We synthesized Y_2.9Ce_0.1Cr_xFe_5-xO₁₂ system and Y_2.9-xCe_0.1Fe_5+xO₁₂ (0≤x≤0.15) single-phase system of samples. The experimental results show that the saturation magnetization of Y_2.9Ce_0.1Cr_xFe_5-xO₁₂ (0≤x≤0.5) system samples decreased with the increase of Cr³⁺ ions doping amount after the first rise. The saturation magnetization of Y_2.9-xCe_0.1Fe_5+xO₁₂ (0≤x≤0.15) sample decrease with x increases. Through the study of magnetic properties above, we have initially known the factors which affected the magnetic properties. These factors including ion types, ion content, ion size, magnetic moments, magnetic domain, anisotropic. These factors will be applied to improve the magnetic properties of the ZnO-based diluted magnetic semiconductor, the ZnO-based diluted magnetic semiconductor nanorods arrays are designed, and we obtained excellent ferromagnetism at room temperature. The work in this respect is very rare reported in the literature.Today the world is dominated by information. Information processing, transmission, storage will continue to call for greater scale and speed. Semiconductor materials to support large-scale integrated circuits and high-frequency devices in the processing and transmission of information plays an important role. These technologies they used are great attributes of the electronic charge. In the information technology, another an indispensable component - information storage (such as tapes, CD-ROMs, hard drives, etc.) is completed by magnetic material, we take full advantage of their electronic properties of spin. However, the research of electronic charge and spin properties and application are developed in parallel, and they are independent each other. At the same time, if we use electronic charge and spin properties, it will set off enormous changes in information technology in future. Diluted magnetic semiconductor material (Diluted Magnetic Semiconductors - DMSs), which is such a property which use of electronic charge and spin properties, it is a new type of semiconductor alloy. Diluted magnetic semiconductor is defined as a magnetic transition metals that is a rare earth element or elements of alternative non-magnetic semiconductor magnetic materials, after the formation of a cation of semiconductor materials and magnetic materials. Both the dual characteristics is a new semiconductor alloy materials.In this paper, through the sol-gel, we synthesized Zn_1-xCo_xO (0≤x≤0.5) diluted magnetic semiconductor nano-powder samples. XRD and AFM tests show that a single-phase sample Zn_0.95Co_0.05O shows wurtzite structure. Magnetic measurements indicate that Zn_0.95Co_0.05O nano-powder samples showed no ferromagnetic at room temperature. We changed ion species, ion content and changed the interaction between magnetic ions, and increased the sample ferromagnetic properties at room temperature.First of all, a total of Cu ions were doped to Zn_0.95Co_0.05O nano-powder samples, through the sol-gel, we synthesize nano-particles Zn_0.93Co_0.05Cu_0.02Osamples. Samples show a ferromagnetic at room temperature, the saturation magnetization is 0.49 emu / g (μ= 0.13μB/Co). Co +2, Cu (+1, +2) exist in Zn_0.93Co_0.05Cu_0.02Omatrix. Cu-Co-doped samples with increased carrier concentration, as a result, it produced ferromagnetism in sample at room temperature. Secondly, though changing oxygen vacancies in the sample content, we synthesized Zn_0.93Co_0.05Cu_0.02O(H) samples. Samples showed ferromagnetic at room temperature, the saturation magnetization is 0.88 emu/g. Oxygen vacancies as a media enhanced magnetic interaction between the spin-spin coupling. The experimental results also show that the separate existence of oxygen vacancies can not produce ferromagnetism at room temperature. Also, we have changed the anisotropic to improve the ferromagnetic properties of samples. We synthesized the samples which grow along the c-axis and they are Zn_0.93Co_0.05Cu_0.02ONanorods arrays, Zn_0.93Co_0.05Cu_0.02Onanorods show single-phase structure. These samples demonstrated excellent ferromagnetic at room temperature, saturated magnetization of these samples is about 0.62 emu / g (μ= 0.16μB/Co). Magnetic anisotropy, the domain wall can, static magnetic energy determined Zn_0.93Co_0.05Cu_0.02ONanorods array and saturation magnetization. There are many ways to improve ZnO based diluted magnetic semiconductor properties of ferromagnetic at room temperature, the research in this field continues to be on going.