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几种新型超硬薄膜的研究进展 总被引:4,自引:0,他引:4
超硬材料主要由Ⅲ,Ⅳ,Ⅴ族共价键化合物(碳化物,氮化物)和单质(金刚石)组成,硬度高于40GPa,有单晶,多晶,非晶等多种,除金刚石外,这些材料都是人工合成的,没有天然对应物,除超硬性质以外,这些材料大都具有宽带隙,高温稳定性,化学惰性等优良的物理化学性质,新型超硬薄膜材料研究从金刚石开始,目前主要的研究对象有金刚石,类金刚石碳(DLC),立方氮化硼(cBN),氮化碳(C3N4,CNx),硼碳氮(BCN)等,是近二十年来材料研究的热门方向之一,文章结合作者近年来的工作,介绍这几种超硬薄膜的研究进展和展望。 相似文献
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较系统地研究了不同衬底材料对制备氮化硼薄膜的影响。用热丝增强射频等离子体CVD法,以NH3,B2H6和H2为反应气体,在Si,Ni,Co和不锈钢等衬底材料上,成功生长出高质量的立方氮化硼薄膜,还用13.56MHz的射频溅射系统将c-BN薄膜沉积在Si衬底上,靶材为h-BN(纯度为99.99%),溅射气体为氩气和氮气的混合气体,所得到的氮化硼薄膜中立方相含量高于90%,用X射线衍射谱和傅里叶变换红谱对样品进行了分析表明,衬底材料与c-BN的晶格匹配情况,对于CVD生长立方氮化硼薄膜影响很大,而对溅射生长立方氮化硼薄膜影响不大。 相似文献
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Preparation of hydrogenated microcrystalline silicon films with hot-wire-assisted MWECR-CVD system 下载免费PDF全文
Intrinsic hydrogenated microcrystalline silicon (\muc-Si:H) films have
been prepared by hot-wire-assisted microwave electron-cyclotron-resonance
chemical vapour deposition (HW-MWECR-CVD) under different deposition
conditions. Fourier-transform infrared spectra and Raman spectra were
measured. Optical band gap was determined by Tauc plots, and experiments of
photo-induced degradation were performed. It was observed that hydrogen
dilution plays a more essential role than substrate temperature in
microcrystalline transformation at low temperatures. Crystalline volume
fraction and mean grain size in the films increase with the dilution
ratio (R=H2/(H2+SiH4)).
With the rise of crystallinity in the films, the optical band gap tends to
become narrower while the hydrogen content and photo-induced degradation
decrease dramatically. The samples, were identified as \mu c-Si:H films, by
calculating the optical band gap. It is considered that hydrogen dilution
has an effect on reducing the crystallization activation energy of the
material, which promotes the heterogeneous solid-state phase transition
characterized by the Johnson--Mehl--Avrami (JMA) equation. The films with the
needed structure can be prepared by balancing deposition and crystallization
through controlling process parameters. 相似文献
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随着稀土的大量开采、冶炼和应用,导致稀土元素正逐渐由岩石圈向水圈和生物圈转移,由此对水环境很可能造成类同重金属的环境负面效应。基于适量稀土对植物生长的促进作用,以四川境内较为常见且易引起水体富营养化的紫背浮萍为研究对象,运用室内受控实验,观测不同浓度稀土Ce3+对紫背浮萍光合作用的影响,并对紫背浮萍鲜重以及培养液进行了15 d的监测。结果表明较低浓度Ce3+(0.30,0.60 mg.L-1)能提高紫背浮萍叶绿素a的含量和碳酸酐酶活性,促进植物的光合作用,其鲜重均高于空白样(P<0.05),并随着时间推移,培养液中DO含量逐渐下降,COD含量则显示出上升趋势;而较高浓度Ce3+(1.50,3.00 mg.L-1)条件下,紫背浮萍叶绿素a和碳酸酐酶活性明显降低,鲜重低于空白样,光合作用下降,植物生长受到抑制。研究结果可知,水域中适量浓度Ce3+(0~0.60 mg.L-1)可提高水生植物光合作用,加快新陈代谢,进而使水质恶化,促进水体富营养化的发生。 相似文献
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