溶胶-凝胶V2O5薄膜的制备及其电化学特性研究

优化了以V2O5粉末、苯甲醇和异丙醇为原料制备V2O5薄膜的溶胶一凝胶技术工艺,使用XRD、FTIR、AFM、UV-VIS-NIR分光光度计和电化学分析等方法研究了薄膜的特性。实验结果表明：采用经过优化的工艺制备的V2O5溶胶为V^4 离子和V^5 离子的混合体,具有很好的稳定性和重复性;随热处理温度的升高,薄膜结构收缩,晶粒长大,V^4 离子逐渐被氧化为V^5 离子;V2O5薄膜具有良好的电化学伏安循环特性。     

PEO／V2O5纳米复合薄膜的变色特性研究

为改善V2O5薄膜的电致变色性能，采用溶胶-凝胶法将具有高离子电导率并具有水溶性的聚环氧乙烷（PEO）直接嵌入V2O5层间，制备了PEO／V2O5纳米复合薄膜。采用标准三电极法从0．5mol／L LiClO4的PC电解质溶液向PEO／V2O5纳米复合薄膜注入锂离子，测量了纳米复合薄膜在注入不同数量锂离子时的可见光透射光谱以及对应的颜色变化，并运用循环伏安法测试其电化学性能。实验结果表明，PEO／V2O5纳米复合薄膜的循环伏安图出现了2对氧化还原峰，并且具有稳定的循环可逆性。随着应用电压的不同，薄膜呈现黄色、绿色和蓝色的多色可逆变化。PEO／V2O5纳米复合薄膜的电化学稳定性和机械性能都优于V2O5干凝胶薄膜，可以作为电致变色材料得到应用。X射线光电子能谱（XPS）成分分析表明PEO／V2O5纳米复合薄膜的电致变色效应与V、O的化合价和化学环境密切相关。     

聚合物嵌入V2O5干凝胶纳米复合材料的合成研究

本文采用溶胶-凝胶方法,将聚合物(PEO)嵌入到V2O5干凝胶层间,制备出(PEO)xV2O5·nH2O纳米复合薄膜材料,利用XRD、TG/DTA、SEM等测试手段分析了复合薄膜的合成过程和状态.结果表明:V2O5干凝胶是在c轴方向有序而a、b轴方向无序的一种层状结构.当PEO嵌入到V2O5干凝胶层间形成纳米复合薄膜材料时,使得V2O5干凝胶层间距明显增大.经热处理后,其层间距由x=0时的11.154A增大到x=2时的14.246A.当x=0.5～1时,PEO嵌入较完全,且复合薄膜表面均匀,无裂纹和孔洞.     

V2O5掺杂对TiO2纳米复合薄膜性能的影响

采用溶胶-凝胶技术,以钛酸丁酯Ti(OC4H9)4、V2O5粉末为原材料制备了纳米结构的TiO2-V2O5复合薄膜.使用XRD、AFM、UV-VIS-NIR分光光度计等方法研究了V2O5对TiO2纳米复合薄膜性能的影响.实验结果表明:V2O5掺杂使复合薄膜表面颗粒尺寸增加,但仍具有纳米孔洞结构;随V2O5含量的增加,TiO2晶相由锐钛矿向金红石的转变率大大提高,使金红石完全转变温度降低了200℃左右;复合薄膜在紫外区域的吸收显著增强,吸收边缘发生了红移.复合薄膜定域态宽度随V2O5含量的增加而增加;光学带隙随V2O5的含量增加而减小.     

V_2O_5复合薄膜材料的制备

本文采用了单壁碳纳米管(SWCNTs)与V2O5气凝胶进行复合.首先采用混酸处理的方法对SWCNTs进行预处理,然后与V2O5溶胶进行复合.V2O5复合气凝胶薄膜材料的制备过程,主要是以v205粉末、苯甲醇(BA)、异丙醇(IP)和SWENTs为原料,采用溶胶-凝胶法、提拉法镀膜和溶剂替换的方法来制备.利用紫外.可见.近红外分光光度计、傅里叶红外光谱仪、原子力显微镜、透射和扫描电子显微镜等表征手段,研究了SWENTs复合V2O5气凝胶薄膜材料的结构和热处理对薄膜性能的影响.     

V_2O_5-TiO_2离子存储电极薄膜的溶胶-凝胶法制备与性能研究

利用无机溶胶-凝胶技术制备了V2O5-(TiO2)x离子存储电极薄膜。采用X射线衍射(XRD)、原子力显微镜(AFM)、Raman光谱、循环伏安法(CV)和紫外-可见光透射光谱分别研究了复合薄膜的微观结构、化学计量、锂离子注入性能以及光学性能。结果表明复合薄膜具有V2O5的层状结构,其c轴方向的结构取向性有所降低;颗粒尺寸和表面粗糙度显著减小;同时TiO2的复合导致薄膜中V2O5的化学计量发生偏移,氧空位数量增多。当x=0.2时,薄膜具有相对较高的离子存储容量及循环稳定性,并且在离子注入/脱出状态均获得相当高的可见光透过性。     

Li2O-V2O5-SiO2薄膜结构与电化学性能研究

采用355nm脉冲激光沉积(PLD)法以Li6.16V0.61Si0.39O5.36为靶制备了Li2O-V2O5-SiO2薄膜.由X射线衍射(XRD)、扫描电子显微镜(SEM)、表面轮廓、交流阻抗(ACI)、直流极化(DCP)等方法对薄膜的形貌、结构及电化学性能进行表征,讨论了Li2O-V2O5-SiO2薄膜电化学性能与其结构的关系.结果表明,该薄膜是一种无针孔和裂缝、厚度均匀、组成致密的非晶态结构;Li2O-V2O5-SiO2薄膜离子电导率与温度符合Arrhenius关系,离子迁移数接近1.0(tion＞99.999%),是一种性能良好的离子导体材料;Li2O-V2O5-SiO2薄膜室温时离子电导率达4.0×10-7S/cm,而电子电导率仅为10-11～10-12S/cm,可作为电解质材料用于全固态薄膜锂电池.     

Al2O3-SiO2纳米复合薄膜的制备及性能研究

以正硅酸乙酯、异丙醇铝为先驱体,甲基三乙氧基硅烷为有机硅烷,采用溶胶-凝胶旋涂方法在普通玻璃和硅片表面镀制纳米复合薄膜.通过FT-IR、VIS透射光谱的分析及薄膜表面接触角的测量,研究了Al2 O3与SiO2配比和热处理温度对复合薄膜的化学结构、透光率及疏水性的影响.结果表明该薄膜具有疏水、致密、透明等性能;Al2 O3的加入未降低复合薄膜的可见光透光率,其中经400℃热处理后不同配比复合薄膜在可见光区的透光率均大于85%,且不影响复合薄膜的疏水性.     

微弧等离子喷涂碳纳米管/纳米Al2O3-TiO2复合涂层高温性能研究

采用等离子喷涂技术制备了5wt%CNTs/Al2O3-TiO2复合涂层,借助SEM、热红联仪和RAM反射率测试系统对CNTs/Al2O3-TiO2复合涂层的组织结构、高温氧化性能、电磁特性进行了分析.结果表明:CNTs/Al2O3-TiO2复合涂层的组织结构致密、孔隙率低,CNTs分散均匀,碳纳米管与Al2O3-TiO2陶瓷粘结剂之间具有良好的界面相容性.在20～700℃高温氧化过程中,CNTs起始失重温度为471.29℃,CNTs/Al2O3-TiO2复合涂层的高温氧化性能有一定提高,起始失重温度从471.29℃提高到507.8℃,而碳纳米管的失重率从100%下降到33.68%.CNTs/Al2O3-TiO2复合涂层具有较好的高温吸波性能,25℃时复合涂层的反射率峰值为-7.86dB.随温度的升高,CNTs/Al2O3-TiO2复合涂层的反射率峰值不断减小,谐振频率向低频移动,300℃时复合涂层的反射率峰值为-12.88dB,小于-5dB频带宽为4.48GHz.     

聚合物修饰V2O5纳米复合薄膜的性能研究

近年来,利用能与锂等碱金属离子发生拓扑化学反应的V2O5、MoO3等层状氧化物的层间结构特征,将聚合物嵌入层间对其进行修饰来改善界面和层间性质,使材料呈现出许多优异的性能,对这类材料合成、结构、性能和界面行为的研究引起了人们的极大兴趣.本文采用通氧气气氛下熔融淬冷法制备V2O5溶胶,采用聚合物溶液直接嵌入的方法,用PEO(聚氧化乙烯)对V2O5层间进行修饰制成(PEO)0.5V2O5·nH2O纳米复合薄膜,并通过直流电导率测试、循环伏安法、紫外-可见光吸光光谱对其电学、电化学、光学性能进行了研究.结果表明,PEO的修饰使V2O5干凝胶薄膜的电学、电化学、光学性能都发生了较大的变化.     

Preparation of ZrO2-CeO2 and HfO2-CeO2 nanopowders

We prepared weakly agglomerated powders of ZrO₂-CeO₂ and HfO₂-CeO₂ solid solutions 5–8 nm in particle size, consisting of monoclinic and tetragonal phases. After heat treatment at 1200°C, the crystallite size was 30 and 14 nm, respectively. We also examined the effect of precipitate freeze drying on the crystallization of hafnia-based solid solutions containing up to 20 mol % CeO₂.     

Comparison of the Electronic Structures of La2CuO4, Sr2CuO2Cl2, and Sr2CuO2F2

First-principles cluster calculations are reported of the local electronic structure of the three compounds: La₂CuO₄, Sr₂CuO₂Cl₂, and Sr₂CuO₂F₂. The copper ${\text{3d}}_{x^2 - y^2 } $ and the planar oxygen 2p _σ atomic orbitals exhibit a similar degree of covalency. The out-of-plane orbitals, however, are quite different with the ${\text{3}}d_{3z^2 - r^2 } $ atomic orbital lowered significantly in energy for chlorine and fluorine apical positions.     

Thermoelectric power of single-phase samples of Tl2CaBa2Cu2O y and Ba2CaSr2Cu2O y

Single-phase 2122 samples of thallium and bismuth superconductors were made by the precursor matrix method. The thermopower of these samples was measured in the temperature range 250 K-T _c . The thermopower was positive and decreased linearly with increasing temperature aboveT _c (onset). The exponential enhancement of thermopower seen in the undoped and doped YBCO was not observed in these samples. The linear variation of thermopower can be explained on the basis of either a two-band model or a narrow band model.     

VLE data for CO2-CF2Cl2, N2-CO2, N2-CF2Cl2 and N2-CO2-CF2Cl

Knowledge about vapour-liquid (VLE) is required as a basis of reliable calculations for separation processes. Correlations available for the prediction of T, p, x, y data are less accurate for mixtures at high pressures and mixtures containing supercritical components. The results of VLE experiments are reported and compared with data calculated with equations of state.     

Structure of Na2O·2TiO2 glass

X-ray radial distribution analysis and Raman spectroscopic measurement were carried out on Na₂O-2TiO₂ glass prepared by twin-roller quenching method. It is found that four-coordinated Ti⁴⁺ ions may be predominant over six-coordinated ones in the present glass. It is also found that the fraction of six-coordinated Ti⁴⁺ ions is larger in the present glass than in K₂O·2TiO₂ and Cs₂O·2TiO₂ glasses. Poorer glass-forming ability of the Na₂O-TiO₂ system compared with the K₂O-TiO₂ and Cs₂O-TiO₂ systems is ascribed to a larger fraction of TiO₆ octahedron for the former system.     

SiO2—TiO2—ZrO2系涂层的制备及其特性

用溶胶－凝胶法（sol-gel method）在不锈钢表面制备了SiO2-TiO2-ZrO2系无机氧化膜（STZ）。用DTA／TG、IR、XRD和SEM等手段研究了涂层制备时由凝胶向玻璃态的转变以及涂层薄膜的显微结构特点，考察了涂层对基体的保护效果。试验结果表明，在溶胶至凝胶最终转变为无机氧化物的过程中形成了无机网络，Si^4 和Zr^4 充当了网络骨架的形成离子。涂层为无定型玻璃态，其间混有石英、锐钛矿或金红石等微晶。     

Elastic and Electronic Properties of Superconducting CaPd 2 As 2 and SrPd 2 As 2 vs. Non-superconducting BaPd 2 As 2

The first-principles calculations were performed to predict the elastic and electronic properties of the superconducting ThCr₂Si₂-type phases CaPd₂As₂ and SrPd₂As₂ in comparison with the non-superconducting CeMg₂Si₂-type phase BaPd₂As₂. Besides, the same properties were compared for CeMg₂Si₂- and ThCr₂Si₂-type polymorphs of BaPd₂As₂. We found that all these phases are mechanically stable and belong to soft materials with low hardness. The near-Fermi region is formed by the valence states of the blocks [Pd₂As₂] with decisive contributions of Pd 4d states. The values of N(E _F) increase in the sequence: CaPd₂As₂ < SrPd₂As₂ < BaPd₂As₂, i.e. in the reverse sequence relative to the transition temperatures T _C. Thus, the change in T _C cannot be explained by the electronic factor, i.e. by the simple correlation T _C～N(E _F). Most likely the decrease in T _C in the sequence CaPd₂As₂ → SrPd₂As₂ and the absence of a superconducting transition in BaPd₂As₂ are related to the structural factors and the peculiarities of the electron–phonon coupling mechanism.     

Investigation of Instability of Lattice of Bi_2Sr_2CaCu_2O_x

Bi2Sr2CaCu2Ox superconductor was studied by differential scanning calorimetry (DSC) and thermogravimetry (TG) in different atmospheres. It is discovered that there is a thermal anomaly in the DSC curve, associated with a weight loss in the TG curve before the melting of the sample. Careful thermal analysis and high temperature X-ray diffraction reveal that the thermal anomaly and the weight loss show an instability of the crystalline Iattice. By annealing the sample in oxygen and argon, respectively and then by TC measurement and thermal analysis, the coincidence of transition temperature with the instability is found. The coincidence is further confirmed by Y-doped 2212 phase.     

Thermal conductivity of the system N2O4 ⇄ 2NO2 ⇄ 2NO + O2

Experimental data on the thermal conductivity of dissociating nitrogen tetroxide have been obtained by the hot-wire method in the temperature range from 290 to 870° K at pressures up to 10⁵ N/m².