响应曲面法优化偏钒酸铵煅烧制备V2O5的工艺（英文）

采用响应曲面法中的中心组合模式对偏钒酸铵煅烧制备V2O5工艺条件进行优化,建立偏钒酸铵煅烧制备V2O5的二次多项式数学模型,探讨主要因素的影响及其交互作用。方差分析结果表明:煅烧温度和煅烧时间对偏钒酸铵的分解率都有显著的影响。采用响应曲面法优化得出的最佳工艺条件为:煅烧温度669.71K,煅烧时间35.9min,物料量4.25g。在最佳工艺条件下,偏钒酸铵的分解率预测值为99.71%,其与实验值99.27%相近,证实回归方程拟合度良好。XRD分析表明,采用响应曲面法所得的煅烧工艺参数是可行的。     

Ageing of V2O5 thin films induced by Li intercalation multi-cycling

Cyclic voltammetry, XPS, RBS and AFM have been combined to study the ageing mechanism of Li intercalation in V₂O₅ thin films prepared by thermal oxidation of vanadium metal. Multi-cycling tests were performed in 1 M LiClO₄-PC in the potential range E ∈ [3.8, 2.8 V] versus Li/Li⁺, corresponding to the α-to-δ phase transition. XPS and AFM were performed using direct anaerobic and anhydrous transfer. Capacity fading remains inferior to 20% during ∼2500 cycles. XPS shows slight modifications of the oxide composition with a V⁴⁺ concentration increasing from ∼5% prior to cycling to ∼16–27% after cycling, due to Li trapped in the oxide film and to the loss of V₂O₅ active material. The presence of lithium carbonate and lithium-alkyl carbonate species evidences the formation of the so-called SEI layer. AFM evidences the loss of crystalline material by grain exfoliation from the outer V₂O₅ layer of the oxide film. By further exfoliation, the inner VO₂ layer of the oxide film is reached and pits are formed, occupying ∼9–13% of the surface. This de-cohesion at grain boundaries is attributed to the strain generated by repeated lattice distortions. After 3300 cycles, the disappearance of lithium carbonates, whereas Li-alkyl carbonates and/or Li-alkoxides remain on the surface, indicates the dissolution and/or conversion of the SEI layer. After 4500 cycles, the oxide film became very labile and could be stripped away by rinsing to reveal the vanadium metal substrate.     

Effect of the organic–inorganic template ICS-PPG on sol–gel deposited V2O5 electrochromic thin film

We produced V₂O₅ thin films with sol–gel technique, using in the synthesis as a template agent, the so-called ICS-PPG. We studied the electrochromic behaviour of thin films with electrochemical techniques as slow scan cyclic voltammetry and cyclic voltammetry (SSCV, CV), impedance spectroscopy (EIS) and potentiostatic intermittent titration (PITT). Moreover, we measured transmittance spectra, optical bandgap of the material and, with the help of transmission electron microscopy (TEM), we found out informations about films structure. The addition of ICS-PPG produces more transparent samples in comparison with samples prepared without template agent. The ion storage capacity is only slightly increased and, with ageing, some deposits appear on the surface limiting the electrochemical performances.     

Influence of phosphorus on Cu sorption kinetics: stirred flow chamber experiments

A stirred flow reactor was used to study the influence of phosphorus on the adsorption and desorption kinetics of copper in two acid soils on granite and amphibolite. The presence of P was found to significantly increase Cu adsorption in both soils, albeit at different types of sites (mainly in slow adsorption sites in the soil on granite, and both in fast and slow adsorption sites in that on amphibolite). The increased Cu sorption at fast sites in the amphibolite soil was due to its high content in Fe oxyhydroxides, which bound P and released OH(-) as a result, thereby raising the pH and leading to a higher sorption capacity during fast reactions. On the other hand, the increased Cu sorption at slow adsorption sites was due to Cu(2+) acting as a bridging element between P and organic matter.     

磷系列新结构环保型阻燃聚酯研究进展

聚酯(PET)具有良好的物理性能,耐摩擦,绝缘性好,冲击强度高,尺寸稳定性好,吸湿性小,电性能好,耐溶剂等优点.但是,和大多数高分子材料一样,PET具有可燃性,氧指数较低等弱点.另外,随着环保要求的不断提升和人们环境意识的逐渐提高,研究和开发环保型阻燃聚酯受到了广泛的关注.而含磷阻燃剂在高温时形成具有P=O和P-O或P...     

Photovoltaic characteristics of phosphorus-doped amorphous carbon films grown by r.f. plasma-enhanced CVD

The phosphorus-doped amorphous carbon (n-C:P) films were grown by r.f. power-assisted plasma-enhanced chemical vapor deposition at room temperature using solid phosphorus target. The influence of phosphorus doping on material properties of n-C:P based on the results of simultaneous characterization are reported. Moreover, the solar cell properties such as series resistance, short circuit current density (J_sc), open circuit current voltage (V_oc), fill factor (FF) and conversion efficiency (η) along with the spectral response are reported for the fabricated carbon based n-C:P/p-Si heterojunction solar cell were measured by standard measurement technique. The cells performances have been given in the dark I–V rectifying curve and I–V working curve under illumination when exposed to AM 1.5 illumination condition (100 mW/cm², 25 °C). The maximum of V_oc and J_sc for the cells are observed to be approximately 236 V and 7.34 mA/cm², respectively for the n-C:P/p-Si cell grown at lower r.f. power of 100 W. The highest η and FF were found to be approximately 0.84% and 49%, respectively. We have observed the rectifying nature of the heterojunction structures is due to the nature of n-C:P films.     

退火温度对高介电常数Ta2O5薄膜电学性能的影响

利用磁控溅射法在硅(Si)衬底上沉积了Ta2O5薄膜,对薄膜进行了不同温度的退火处理,并利用X射线衍射仪对薄膜的微观结构进行了分析.然后在Si的背面和介电薄膜的上面沉积Pt电极,组成了金属—氧化物—半导体( MOS)电容器,对不同温度下退火得到的薄膜制备的MOS电容器的电学性能进行了研究.结果表明,薄膜在700℃开始结...     

Internal reflection ellipsometry for real-time monitoring of polyelectrolyte multilayer growth onto tantalum pentoxide

Internal reflection ellipsometry was used for detection of the consecutive coating of two polyelectrolytes, poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA), onto a tantalum pentoxide (Ta₂O₅) substrate until the 10th bilayer. The UV patterned PAH-PAA-multilayer was characterized in air via ellipsometry and atomic force microscopy. Suited optical models enabled the determination of the layer thicknesses in wet and dry states. Linear multilayer formation could be proved by Attenuated Total Reflection — Fourier Transformed Infrared Spectroscopy measurements following the increase of the ν(C=O) band depending on the adsorption of the PAA. Streaming potential measurements after each layer deposition step indicated a change in surface charge after each layer deposition due to the consecutive coating of PAH and PAA. In this article the internal reflection ellipsometry is shown to be a convenient possibility to analyze the modification of a thin transparent Ta₂O₅ substrate.     

The arsenic for phosphorus swap is accidental, rather than a facultative one, and the question whether arsenic is nonessential or toxic is quantitative, not a qualitative one

Arsenic shares many physicochemical properties with phosphorus, so that arsenic can be taken up inadvertently by cells through the pathways for phosphorus. As a phosphate analog, arsenate competes with phosphate and enters cells via phosphate transporters. In the cell, arsenate can be recognized as a substrate by enzymes that usually use phosphate as a substrate. The phosphate for arsenate swap results in wasteful ‘futile cycles’ in metabolic pathways, uncoupled oxidative phosphorylation and extreme DNA instability. The disrupting metabolic effects of arsenic have an evolutionary meaning, so that all living organisms—from chemoautotrophic organisms that grow by reducing or oxidizing arsenic to metazoan—carry highly conserved arsenic resistance genes. Arsenic resistance can result from different strategies including selective transport to maximize phosphate uptake and minimize entry of arsenate, active transport to export arsenate, arsenic storage in specialized compartments, enzyme selectivity toward phosphate, and increased efficiency of DNA repair systems. None of these strategies is infallible, though, and susceptibility to arsenic toxicity varies between taxa in many orders of magnitude. Even arsenic-hypertolerant organisms will stop to grow and will eventually die when exposed to arsenic over species-specific resistance limits. The arsenic for phosphorus swap is an accidental one, it does not warrant a conclusion in favor of the essentiality of arsenic to life as we know it.     

镍腐蚀的影响因素与改善方法探讨

镍腐蚀是指发生在化学镍金的化镍、沉金过程中发生的金对镍的攻击过度造成局部位置或整体位置镍腐蚀的现象,严重者则导致＂黑盘＂的出现,严重影响PCB的可靠性。报告通过评估分析镍腐蚀影响的因素,提出相应的改善方法,改善流程的稳定性。