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北京石油化工學院2026年研究生招生接收調劑公告

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[求助] 高分子材料論文翻譯求助

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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多層膜的形態(tài)。
使用AFM測定每一層膜的形態(tài)，其測定結果如圖1所示。所有的膜沒有微裂隙，每一層膜的顏色連續(xù)一致。眾所周知的是二氧化鈦膜是無色的，鐵鋇氧體膜是棕色的。每一層膜顏色的一致性表明復合膜是均勻的。隨著膜層數的增加，復合膜的顏色加深。每層膜的形態(tài)與其他的都不相同。單層膜看起來不是非常均勻，有一些60-180nm的洞在里面。單層膜中的顆粒并不是均勻一致的，其大小范圍為30-120nm。與單層膜相比較，兩層膜和三層膜的表面更好，洞較少。二層膜中的顆粒相對均勻，大小范圍為30-60nm。三層膜中有一些較大顆粒出現，最大顆粒為240nm。底物與層數是影響膜增長的重要因素。第一層膜在石英玻璃盤上生長。結構差異使膜困難地生長，因此缺點就顯而易見的顯現出來，顆粒是無序的。但是，第二層膜在第一層膜的基礎上生長，其生長條件得到改善，在第一層膜的指導下生長的更好。隨著層數的增加，一些顆粒有機會在三維長大。在三層膜中，一些顆粒甚至長到240nm。此外，TiO2和陶瓷鐵顆粒在復合膜中不能被區(qū)分。
多層膜的晶體結構
使用溶膠——凝膠方法制備替代BaFe12O19物過程中，中間結果包括Fe2O3, BaCO3和 BaFe2O4將會出現。在多層膜形成過程中，如果他們與TiO2嚴重反應，預期的磁性材料替代的鋇陶鐵磁體不會形成。XRD用于測定復合膜的晶體結構，其模型如圖2所示。復合膜室友金紅石二氧化鈦和M-型六邊鋇陶鐵磁體組成。在該模型中沒有發(fā)現Al2O3和Cr2O3的衍射峰，這表明所有的Al3+和Cr3+離子全部進入BaFe12O19晶格中�？梢缘玫竭@樣的結論：在煅燒過程中混和溶膠基礎地反應成為替代的BaFe12O19和TiO2。被替代的鋇陶鐵磁體能夠被二氧化鈦作為一個矩陣通過溶膠——凝膠方法合成。此外，在XRD模型上有兩個不能被標準卡認識的未知弱衍射峰。可能小部分Fe、Ti和O元素仍反應成為一種非化學計量的化合物。
多層膜的微波吸收性能。
微波衰減材料吸收寬頻率范圍微波能。單一材料不能容易做到這一點。鋇陶鐵磁替代物被選擇與TiO2制備復合多層膜。這些膜根據他們的微波吸收峰的頻率排列。BaFe10.1Al1.9O19的吸收頻率最高，因此含有BaFe10.1Al1.9O19的復合層作為底物附近的第一層。BaFe11.4Cr0.6O19的吸收頻率最低，因此該復合層位于最上層。含有BaFe10.5Al1.5O19的復合層位于中間。這種排列能夠使更多的微波能進入多層膜并被吸收。復合多層膜的微波損失譜如圖3所示。BaFe10.1Al1.9O19、BaFe10.5Al1.5O19和BaFe11.4 Cr0.6O19粉末的微波損失譜最為對比同時展示出來了。復合多層膜的微波吸收性能是卓越的。最大損失率接近–40 dB。損失高于–10 dB的頻率范圍高于7 GHz。這是一種理想的微波吸收材料。由于多變的吸收頻率，每層膜能夠吸收不同頻率帶的微波能。多層膜聚集了每層膜的成就。此外，陶鐵磁體與TiO2復合物能夠幫助微波吸收。鋇陶鐵磁體是一種磁性材料，TiO2是一種非磁性材料。他們復合在一起之后，磁性材料的電磁特點被改變了。眾所周知的是幾乎所有的鐵氧磁體沒有介電損失�，F在與TiO2形成復合物能夠改善鋇陶鐵磁體替代物的介電損失。此外，多層膜中大多數顆粒的大小屬于納米范圍，這是由于TiO2顆粒的周圍。具有單一磁性域結構的陶鐵磁體顆粒不能長大，并轉變成為多域結構，由于TiO2顆粒的聚集，這種聚集增加了微波吸收。

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無論如何，做事要有始有終！就算洗馬桶也要比別人洗的干凈！

2樓2014-04-09 17:27:09