314 resultados para sensibilité au pH
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本文研究了Armco铁在盐酸溶液中的腐蚀电化学行为,探讨了ψ~-离子和PH值对铁的阳极溶解过程的影响,并进而讨论了ψ~-离子浓度和PH值对铁的腐蚀电化学行为的影响之间是否存在交互效应。在本工作中,作者提出了两个新的研究方法:(a) 从单支弱极化曲线测定腐蚀电流和阴、阳极反应的Tafep斜率;(b)根据交流方波电流扰动的响应函数方程测定极化电阻Rp和界面电容C。设I_c、I_(2c)、I_(3c)及I_(4c)分别为对应于弱极化区内极化电位为ΔE、2ΔE、3ΔE和4ΔE的极化电流,且令a = I_(2c)/I_c, b = I_(3c)/I_c, c = I_(4c)/I_(2c), 而(4b-3a~2)~(1/2)、(3c-2b)~(1/2)、(2c-a~2)~(1/2)则以S_j表示之,则可得到:I_(corr) = I_c/S_j b_c = ΔE/lg((a+s_j)/2) b_a = -ΔE/lg((a-s_j)/2)为了方便,准确地求出动力学参数,可选用一系列的ΔE值,得出相应的极化电流I_λ,求出S_λ,应用统计方法处理数据,可得:I_(corr) = ∑ from i=1 to n I_λ/∑ from i=1 ton S_λ b_c = ∑ form λ to n ΔE_λ/∑ form i=1 to n lg ((a_λ+S_λ)/2) b_a = ∑ form i=1 ton ΔE_λ/∑ form i=1 to n lg ((a_λ-S_λ)/2)在线性极化区间内向腐蚀金属电极体系施加一交流方波电流扰动讯号时,通过Laplace变换分析,得到相应的响应函数方程为:E_1(t) = λ_o(R_s+R_p) - 2λ_oR_p (e~(-(τ-λ)/RpC))/(1+e~(λ/RpC)) (o<τ<λ) E_2(t) = -λ_o(R_s+R_p) + 2λ_oR_p (e~(-(τ-λ)/RpC))/(1+e~(λ/RpC)) (λ<τ<2λ)由此方程可知,它们在E~λ坐标系统中的轨迹为对称兴致勃勃原点的两条直线。由此方程可进一步得到:ΔE = 2λ_oR_p (e~(λ/RpC)-1)/(e~(λ/RpC)+1) = 2λ_oR_p t_(anh)(λ/(2RpC)) Δh = 2λ_o Rs式中ΔE为单支响应直线的长度,Δh则为两条直线最高点之间的距离。上述公式可进一步简化为:Rp =(ΔE)/(2λ_o) λ>>RpC (λ_o)/(ΔE) = C/λ + 1/(2Rp) λ<
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PEO/PH共混体系的组份之间存在着氢键的相互作用,从偏光显微镜观察及熔点下降法测定,PEO/PH共混体系是相容体系,且PEO是在非晶区与PH相容,PH分子链不进入到PEO的晶格中,不引起晶胞参数的改变。对PEO/PH共混体系的等温结晶动力学研究表明,随共混体系中非晶组份PH含量的增加,体系的结晶生长方式由盘状生长转化为原纤状生长,成核方式由方式I(Kg=Kg(I)=4b. σσeTm/ΔHf.K)转化为方式II(Kg=Kg(Ii)=2b. σσeTm/ΔHf.K)析叠链表面自由能(σe)逐渐增大,体系的平衡溶点降低。在PEO/PH共混体系非等温结晶动力学的研究中,DSC实验表明,在常冷却速率下,PEO/PH共混体系符合Avrami方程所揭示的规律,为更好地反映非等温结晶特点,从Avrami方程和Ozawa方程出发,导出一个新的基本方程,根据这个方程,获得了描述非等温结晶过程的一些基本参数,在一定冷却速率下,随非晶组份PH含量的增加,东混体系的结晶速率降低;对于同一组成,冷却速率越大,体系结晶速率越快。WAXD和SAXS分析表明,随非晶组份PH含量的增加,PEO/PH共混体系的结晶度降低,长周期增大,过渡层厚略有变化,但变化很小。进一步表明,过渡层基本上是PEO的非晶相的贡献,PH不进入到PEO的晶格中,PEO是在非晶区与PH相容。
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Up to now, in most of the research work done on the effect of hydrogen on a Schottky barrier, the hydrogen was introduced into the semiconductor before metal deposition. This letter reports that hydrogen can be effectively introduced into the Schottky barriers (SBs) of Au/n-GaAs and Ti/n-GaAs by plasma hydrogen treatment (PHT) after metal deposition on [100] oriented n-GaAs substrates. The Schottky barrier height (SBH) of a SB containing hydrogen shows the zero/reverse bias annealing (ZBA/RBA) effect. ZBA makes the SBH decrease and RBA makes it increase. The variations in the SBHs are reversible. In order to obtain obvious ZBA/RBA effects, selection of the temperature for plasma hydrogen treatment is important, and it is indicated that 100-degrees-C for Au/n-GaAs and 150-degrees-C for Ti/n-GaAs are suitable temperatures. It is concluded from the analysis of experimental results that only the hydrogen located at or near the metal-semiconductor interface, rather than the hydrogen in the bulk of either the semiconductor or the metal, is responsible for the ZBA/RBA effect on SBH.
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Interfacial formation processes and reactions between Au and hydrogenated amorphous Si have been studied by photoemission spectroscopy and Auger electron spectroscopy. A three-dimensional growth of Au metal cluster occurs at initial formation of the Au/a-Si:H interface. When Au deposition exceeds a critical time, Au and Si begin interdiffusing and react to create an Au-Si alloy region. Annealing enhances interdiffusion and a Si-rich region exists on the topmost surface of Au films on a-Si:H.
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The Ni/Au contact was treated with oxalic acid after annealing in O_2 ambient, and its I-V characteristic showed the property of contact has been obviously improved. An Auger electron spectroscopy (AES) depth pro-file of the contact as-annealed showed that the top layer was highly resistive NiO, while an X-ray photo-electron spectroscopy (XPS) of oxalic acid treated samples indicated that the NiO has been removed effectively. A scanning electron microscope (SEM) was used to observe the surface morphology of the contacts, and it was found that the lacunaris surface right after annealing became quite smooth with lots of small Au exposed areas after oxalic acid treatment. When the test probe or the subsequently deposited Ti/Au was directly in contact with these small Au areas, they worked as low resistive current paths and thus decrease the specific contact resistance.
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采用化学气相沉积(CVD)方法在Si(001)衬底上分别制备了有金属Au缓冲层以及无Au缓冲层的ZnO薄膜。其中Au缓冲层在物理气相沉积(PVD)设备中蒸发,厚度大约为300nm。有Au缓冲层的ZnO薄膜晶体质量比直接在Si衬底上生长有了显著提高。利用X射线衍射(XRD)研究了所生长ZnO薄膜的结晶质量,有Au缓冲层的ZnO薄膜虽然仍为多晶,但显示出明显的择优取向。用光学显微镜研究了ZnO薄膜的表面特征,金属Au缓冲层显著地提高了在Si衬底上生长的ZnO薄膜的晶粒尺寸及平整度。同时利用室温光致发光(PL)谱研究了ZnO薄膜的光学性质,并分析了有Au缓冲层的ZnO薄膜NEB发光峰强度反而弱的可能原因。
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在MBE和MOCVD两种方法制备的n-GaN材料上制作了Au-GaN肖特基结,测定了肖特基结的室温I-V特性。分析表明
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于2010-11-23批量导入
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于2010-11-23批量导入
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于2010-11-23批量导入
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This paper introduced a long-term ambulatory intragastric pH monitoring system, which is designed for prolonged ambulatory studies of Gastroesophageal Reflux Diseases. The whole system is composed of the gastric catheter with two pH sensors, a small data logger (Microdatalog), and a notebook PC. In this paper, the design of monitoring system hardware and software are described in detail. Clinical applications reveal good results.