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采用理论计算方法解释了氨逐级解离能降低的现象。计算结果表明,随着N与H原子结合数目的减少,键解离能降低、键长增长;随着N与H原子结合数目的增多,N的2s电子跃迁到N的2p轨道上的几率增大,减小了屏蔽作用;更多电子从H的1s轨道迁移到N的2p轨道,增大了N和H之间的静电作用;单电子或孤对电子与N-H键夹角的增大减小了排斥作用。这3个因素造成NH3的逐级键解离能有降低的趋势。 相似文献
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本文介绍了棒状NiCo2O4的制备,并将其修饰玻碳电极作为无酶葡萄糖传感器. 通过简单的水热反应合成了NiCo2O4,然后在商用微波炉中对NiCo2O4进行处理,以消除水热合成过程中可能引入的残存水. 扫描电镜、透射电镜、X射线衍射谱和X射线光电子能谱分析表明,微波处理前后结构无变化. 通过EDS对Ni,Co,O原子比例的分析,证明微波处理对残存水的消除作用. 微波处理的NiCo2O4(M-NiCo2O4)作为葡萄糖传感器的灵敏度高达431.29 μA mM-1 cm-2. 最后,将M-NiCo2O4在水中浸泡不同时间后,其对葡萄糖的感应性能下降. 结果表明,水热过程中引入的残存水对其电化学性能有很强的影响,微波预处理对其电化学性能也有着重要的影响. 相似文献
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Hexagonal CuSCN and cubic Cu2S micro-scale crystallites have been selectively fabricated using CuCl2·2H2O and KSCN as the starting materials at 30 ℃ and 220 ℃, respectively. The results reveal that the reaction temperature plays a key role in obtaining pure phase of CuSCN and Cu2S crystallites. Nearly monodispersed Cu2S nanocrystals were prepared by introducing surfactant into reaction system. The possible reaction mechanism is also discussed. 相似文献
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采用MP2/6-311+G**理论方法考察了甲基自由基和硅甲基自由基的结构和电子性质。结果表明,甲基自由基上的C和H分别带负电荷和正电荷,而硅甲基自由基上的Si和H分别带正电荷和负电荷。无论是甲基自由基还是硅甲基自由基,锥形结构的中心原子成键轨道的p轨道成分多于平面结构的p轨道成分;平面结构比锥形结构的中心原子更倾向于负电性化。甲基自由基的Laplacian电子密度值的符号为负,而硅甲基自由基的Laplacian电子密度值的符号为正。从而证实了Pauling关于电负性差异导致结构不同的论断。 相似文献
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采用计算化学模拟方法,在MP2/6-311+g(d),B3LYP/6-311+g(d),HF/6-311+g(d),ωB97XD/6-311+g(d)水平上考察了NCl3的自然布居分析电荷(natural population analysis, NPA电荷)、原子偶极矩校正的Hirshfeld布居电荷(atomic dipole moment corrected Hirshfeld population,ADCH电荷)、分子中的原子理论电荷(atoms in molecules,AIM电荷)和自然电子构型。模拟结果表明,N的化合价为负,而Cl的化合价为正。 相似文献
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A facile synthesis route has been developed to prepare barium titanate nanoparitcles via a low temperature (120 ℃) hydrothermal decomposition of single-source metal-organic precursor. A mixture of tetramethylammonium hydroxide (TMAH) and distilled water was used as reaction media, and Barium titanium ethyl-hexano- isoproxide [BaTi(O2CC7H15)(OC3H7)5] was used as precursor. The architecture of products can be selectively controlled from nanorods to nanospheres by adjusting the precursor′s concentration in the reaction system. Powder X-ray diffraction (XRD) analysis indicated that the products were in cubic phase. Transmission electronic microscopy (TEM) observation showed that the nanospheres were 30~50 nm in diameter, and the nanorods were 5~10 nm in diameter and 100~600 nm in length, respectively. Phase transformation behavior of the as-prepared products was also investigated. 相似文献
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化学气相沉积法制备氮化钛 总被引:5,自引:0,他引:5
本文以氮化钛的CVD制备为例,说明了源物质的选择对CVD过程的影响.在此基础上,综述了化学气相沉积技术在材料制备领域的最新进展. 相似文献
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