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高分子材料论文翻译求助
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Morphology of multilayer film。The morphology of each layer film was investigated with AFM. The results are displayed in Fig. 1. The Films have no microcracks and are individually consistent in color. It is known that the titanium dioxide film is achromatous and barium ferrite film is brown. The consistent in color of each layer film shows that the composite film is uniform. With the increase of layer, the color of composite film becomes heavier. The morphology of each layer film is different to others. The one layer film is looked not very even. Some cavities appear in it. The size of cavities changes from 60 to 180 nm. The grains in the one layer film are not homogeneous. The size changes from 30 to 120 nm. Compared with the one layer film, the surface of the two and three layer film is bettered. The cavity is few,and the grains are relative uniform in the two layer film. The size of grains changes from 30 to 60 nm. In the three layer film, some big grains appear, with the maximum size of 240 nm. The substrate and layer number are important factors to affect the growth of films. The first layer film grows on the quartz glass plate. The difference in structure makes the film to grow difficultly. So the defects easily appear and grains are unordered. However, the second layer film grows on the base of the first layer film. The growth conditions are improved for the second layer film. It can grow better under the direction of the first layer film. With the increase of layer number, some grains have chance to grow big in three dimensions. In the three layer film, some grains even grow to 240 nm. Additionally, the TiO2and ferrite grains can not be distinguished in the composite film. Crystalline structure of multilayer film In the course of preparing substituted BaFe12O19using sol–gel method, the intermediate results including Fe2O3, BaCO3and BaFe2O4will appear. If they react heavy with TiO2during the formation of multilayer film, the expected magnetic materials, substituted barium ferrites will not form. XRD is used to inves-tigate the crystalline structure of composite film and its pattern is shown in Fig. 2. The composite film is composed of rutile titanium dioxide and M-type hexagonal barium ferrite. The diffraction peaks of Al2O3and Cr2O3are not found on the pattern, which shows that all of Al3+and Cr3+ions have entered the lattice of BaFe12O19. It is concluded that the mixed solsbasically react into the substituted BaFe12O19and TiO2 during the calcination process. The substituted barium ferrite can be synthesized via titanium dioxide as amatrix using sol–gel method. In addition, there are two unknown weak diffraction peaks on XRD pattern,which can not be recognized by standard cards. Maybe,a little part of Fe, Ti and O elements still reacted into an unstoichiometric compound. Microwave absorption property of multilayer film Microwave attenuation materials are required to absorb microwave energy in a broad frequency range.Single material is not easy to realize it. Substituted barium ferrites are selected to prepare composite multilayer film with TiO2. These films are arranged according to the frequencies of their microwave absorption peaks. The absorption frequencies of BaFe10.1Al1.9O19 are the highest, so the composite layer containing BaFe10.1Al1.9O19is treated as the first layer nearby the substrate. The absorption frequencies of BaFe11.4Cr0.6O19 are the lowest, and then the composite layer containing it is on the top. Thecomposite layer containing BaFe10.5Al1.5O19is in the middle. This arrangement can make more microwave energy to enter the multilayer film and to be absorbed.The microwave loss spectrum of composite multilayer film is shown in Fig. 3. The microwave loss spectra of BaFe10.1Al1.9O19, BaFe10.5Al1.5O19 and BaFe11.4 Cr0.6O19 powders are simultaneously displayed as a comparison. The microwave absorption property of the compos-ite multilayer film is excellent. The largest loss efficiency is close to –40 dB. The frequency range with the loss above –10 dB is more than 7 GHz. It is an ideal microwave absorption material. Because of the variable absorption frequency, each layer film can absorb microwave energy in different frequency band. The multilayer film assembles the achievements of each layer. Moreover, the compounding of ferrites with TiO2is helpful for the microwave absorption. Barium ferrite is a magnetic material, and TiO2is a nonmag-netic material. After they are compounded together, electromagnetic properties of magnetic material can be changed. It is known that almost all of ferrites have little dielectric loss. Now the compounding with TiO2 can improve the dielectric losses of substituted barium ferrites. Additionally, the size of most grains in multilayer film belongs to nanometer scope, which is attributed to the surround of TiO2particles. The ferrite grains with single magnetic domain structure can notgrow big and convert into multi-domain structure, due to the block of TiO2particles, which also increase the microwave absorbing. |
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多层膜的形态。 使用AFM测定每一层膜的形态，其测定结果如图1所示。所有的膜没有微裂隙，每一层膜的颜色连续一致。众所周知的是二氧化钛膜是无色的，铁钡氧体膜是棕色的。每一层膜颜色的一致性表明复合膜是均匀的。随着膜层数的增加，复合膜的颜色加深。每层膜的形态与其他的都不相同。单层膜看起来不是非常均匀，有一些60-180nm的洞在里面。单层膜中的颗粒并不是均匀一致的，其大小范围为30-120nm。与单层膜相比较，两层膜和三层膜的表面更好，洞较少。二层膜中的颗粒相对均匀，大小范围为30-60nm。三层膜中有一些较大颗粒出现，最大颗粒为240nm。底物与层数是影响膜增长的重要因素。第一层膜在石英玻璃盘上生长。结构差异使膜困难地生长，因此缺点就显而易见的显现出来，颗粒是无序的。但是，第二层膜在第一层膜的基础上生长，其生长条件得到改善，在第一层膜的指导下生长的更好。随着层数的增加，一些颗粒有机会在三维长大。在三层膜中，一些颗粒甚至长到240nm。此外，TiO2和陶瓷铁颗粒在复合膜中不能被区分。 多层膜的晶体结构 使用溶胶——凝胶方法制备替代BaFe12O19物过程中，中间结果包括Fe2O3, BaCO3和 BaFe2O4将会出现。在多层膜形成过程中，如果他们与TiO2严重反应，预期的磁性材料替代的钡陶铁磁体不会形成。XRD用于测定复合膜的晶体结构，其模型如图2所示。复合膜室友金红石二氧化钛和M-型六边钡陶铁磁体组成。在该模型中没有发现Al2O3和Cr2O3的衍射峰，这表明所有的Al3+和Cr3+离子全部进入BaFe12O19晶格中。可以得到这样的结论：在煅烧过程中混和溶胶基础地反应成为替代的BaFe12O19和TiO2。被替代的钡陶铁磁体能够被二氧化钛作为一个矩阵通过溶胶——凝胶方法合成。此外，在XRD模型上有两个不能被标准卡认识的未知弱衍射峰。可能小部分Fe、Ti和O元素仍反应成为一种非化学计量的化合物。 多层膜的微波吸收性能。 微波衰减材料吸收宽频率范围微波能。单一材料不能容易做到这一点。钡陶铁磁替代物被选择与TiO2制备复合多层膜。这些膜根据他们的微波吸收峰的频率排列。BaFe10.1Al1.9O19的吸收频率最高，因此含有BaFe10.1Al1.9O19的复合层作为底物附近的第一层。BaFe11.4Cr0.6O19的吸收频率最低，因此该复合层位于最上层。含有BaFe10.5Al1.5O19的复合层位于中间。这种排列能够使更多的微波能进入多层膜并被吸收。复合多层膜的微波损失谱如图3所示。BaFe10.1Al1.9O19、BaFe10.5Al1.5O19和BaFe11.4 Cr0.6O19粉末的微波损失谱最为对比同时展示出来了。复合多层膜的微波吸收性能是卓越的。最大损失率接近–40 dB。损失高于–10 dB的频率范围高于7 GHz。这是一种理想的微波吸收材料。由于多变的吸收频率，每层膜能够吸收不同频率带的微波能。多层膜聚集了每层膜的成就。此外，陶铁磁体与TiO2复合物能够帮助微波吸收。钡陶铁磁体是一种磁性材料，TiO2是一种非磁性材料。他们复合在一起之后，磁性材料的电磁特点被改变了。众所周知的是几乎所有的铁氧磁体没有介电损失。现在与TiO2形成复合物能够改善钡陶铁磁体替代物的介电损失。此外，多层膜中大多数颗粒的大小属于纳米范围，这是由于TiO2颗粒的周围。具有单一磁性域结构的陶铁磁体颗粒不能长大，并转变成为多域结构，由于TiO2颗粒的聚集，这种聚集增加了微波吸收。 |
2楼2014-04-09 17:27:09
