Doping strategy to boost electromagnetic property and gigahertz tunable electromagnetic attenuation of hetero-structured manganese dioxide.
Doping strategy to boost electromagnetic property and gigahertz tunable electromagnetic attenuation of hetero-structured manganese dioxide.
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DOI：
10.1039/c8dt04372h
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发表时间：
2019-02
影响因子：
4
通讯作者：
Gaihua He;Yuping Duan;Lulu Song;Xuefeng Zhang
中科院分区：
文献类型：
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作者：
Gaihua He;Yuping Duan;Lulu Song;Xuefeng Zhang
采用一种简单易行的化学方法，在不添加任何表面活性剂或有机模板剂的情况下，合成了新型三维结构的镍掺杂ε-MnO 2。镍盐直接作为试剂而不是作为添加剂来生产掺杂二氧化锰，这与绝大多数用于电磁波吸收材料的掺杂MnO 2的先前合成方法不同。这种方法克服了以前报道的掺杂少量金属离子的方法的缺点，有时很难检测。用电子探针（EPMA）和能谱仪（EDS）分析了样品的化学成分。用X射线光电子能谱（XPS）分析了复合材料中元素的化学状态。用扫描电镜（SEM）和透射电镜（TEM）对微球的结构进行了表征。结果表明，自组织晶体是由核桃状球体组成的多晶阵列。通过EPMA、EDS、XPS和暗场扫描TEM等测试，证明镍离子已成功地掺杂到晶体中。因此，构建了多异质结结构。Ni掺杂后，晶相仍为ε型，形貌转变为核桃状结构。电磁性能也表现出显着的变化与镍离子的引入。与商用MnO 2相比，镍掺杂MnO 2具有降低的介电常数，而镍掺杂MnO 2似乎具有迷人的磁性，最大磁损耗角正切值为0.37，是介电损耗角正切值的7倍。同样，它进一步提出，最佳的电磁容量有关的核桃状二氧化锰球在复合材料中的质量分数。当质量分数高达50%时，磁损耗角正切随着突变以及弛豫时间以及相对复磁导率的真实的部分和虚部分的明显增加而上升。此外，突出的电磁衰减的机制进行了详细的探讨。
A facile and simple chemical route has been used to synthesize novel three-dimensional (3D) architectures of nickel-doped ε-MnO2 without the addition of any surfactant or organic template. Nickel salt is used directly as the reagent rather than as an additive to produce doped manganese dioxide, which is different from the overwhelming majority of previous synthetic methods for doped MnO2 for use as an electromagnetic wave absorption material. This method overcomes the shortcomings of the previously reported approaches of doping with a slight amount of metallic ion, which is sometimes hard to detect. The chemical composition of the samples is analyzed by electron-probe micro-analysis (EPMA) and energy dispersive spectroscopy (EDS). The chemical state of the elements in the composites is demonstrated with X-ray photoelectron spectroscopy (XPS). The structures of the micro-spheres are detected by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the self-organized crystals are made up of walnut-like spheres and are arrays of polycrystals. The nickel ion is certified to have been successfully doped into the crystal based on the results of EPMA, EDS, and XPS as well as dark field scanning TEM. Thus, a multiple heterojunction structure is constructed. After nickel doping, the crystalline phase remains ε type and the morphology turns into a walnut-like structure. Electromagnetic performances also exhibit significant variation with the introduction of nickel ions. Nickel-doped MnO2 has a decreased dielectric constant compared with that of commercial MnO2, while the nickel-doped MnO2 appears to have fascinating magnetic properties with a maximum magnetic loss tangent value of 0.37, which is 7 times greater than that of the dielectric loss tangent. Likewise, it is further presented that the optimized electromagnetic capacities are related to the mass fraction of the walnut-like MnO2 spheres in the composite. When the mass fraction is as high as 50%, the magnetic loss tangent goes up with a distinct increase in mutations as well as in relaxation times and in the real part and the imaginary part of the relative complex permeability. Furthermore, the mechanisms of the highlighted electromagnetic attenuation are explored in detail.