膜厚可调CuS对电极的研制与光伏应用

利用化学浴沉积法在FTO基底上制备了厚度可调CuS对电极(CE).通过X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见(UV-Vis)分光光度计及电化学工作站对CuS对电极的物相结构、微观形貌、光学性质及电化学性能进行了表征.结果表明,在多硫电解液体系中,CuS对电极的电催化活性优于Pt电极;调控沉积周期,可进一步优化CuS对电极表面形貌及电化学性能;CuS对电极最佳沉积周期为6个周期(C),此时电荷转移电阻达到最小值0.67Ω/cm2,与CdSe胶态量子点敏化TiO2光阳极组装的电池,能量转换效率可达2.11;.     

多壁碳纳米管对电极染料敏化太阳能电池的性能研究

以SnO2/TiO2薄膜为光阳极,与以经酸化处理和与石墨复合的沉积在FTO导电基底的多壁碳纳米管(MWCNTs)薄膜为对电极,I-/I3-为电解液,组装成染料敏化太阳能电池.对电极通过循环伏安法(CV曲线)、电化学阻抗谱(EIS)及极化曲线法(Tafel曲线)进行电化学催化性能的表征,组装后的电池通过伏安特性曲线(J～V)进行光电性能分析,结果表明:酸化处理及与石墨复合有利于提高对电极的催化性能及电池光电性能.开路电压及短路电流密度分别可达0.53 V、4.67 mA/cm2,其中短路电流较未经过处理的MWCNTs对电极提高27.4;,同时讨论了对电极电化学性及电池光电性能增强的机制.     

多孔NixCoyS薄膜在染料敏化太阳能电池中的应用研究

为了进一步提高基于硫化镍钴电极的染料敏化太阳能电池光伏性能,将以自组装形成的二维聚苯乙烯光子晶体为模板,采用反向恒压电沉积技术制备一种具有多孔结构的硫化镍钴薄膜(NixCoyS-PC),并直接作为对电极应用于染料敏化太阳能电池中.对比测试结果发现,NixCoyS-PC电极展现出了比无多孔结构的硫化镍钴(NixCoyS-FTO)电极、铂电极更加优异的电催化性能,这是因为多孔结构有利于提高其电催化活性位点及氧化还原电对I-/I3-的扩散速率.因此,基于NixCoyS-PC电极的染料敏化太阳能电池展现出了较高的光电转换效率(5.80;),高于基于NixCoyS-FTO电极(5.43;)和铂电极(4.87;)的电池效率.     

液相沉积法处理TiO2纳米晶膜对其光电性能的影响

将涂有TiO2纳米晶膜的导电玻璃浸渍于氟钛酸铵、硼酸和水的液相沉积(Liquid Phase Deposition,简称LPD)反应溶液中,利用反应液中氟的金属配位离子和金属氟化物之间的化学平衡反应,在TiO2纳米晶多孔膜(简称nc-TiO2膜)上沉积一层TiO2纳米粒子,从而实现对TiO2纳米晶膜进行化学处理。以经过LPD处理的TiO2纳米晶膜作为光阳极组装染料敏化太阳能电池(DSSC)并测试其伏安特性曲线,研究了不同反应时间条件下LPD处理nc-TiO2膜对DSSC光电性能的影响。结果表明:在一定条件下用LPD处理TiO2纳米晶膜可显著提高其DSSC光电性能,短路电流密度最高提高13.13%,能量转化效率最高提高13.95%。论文对LPD处理TiO2纳米晶膜提高DSSC光电转化性能的原因进行了分析。     

CdS量子点敏化ZnO薄膜的制备及其性能研究

本文以Zn(CH3COO)2·2H2O、CdCl2和硫脲的水溶液分别为前驱体,采用超声喷雾热解法在ITO导电玻璃上成功的制备了CdS量子点敏化ZnO薄膜(ZnO∶ CdS).通过扫描电镜(SEM),X射线衍射(XRD),光致发光(PL)谱和吸收光谱对CdS量子点敏化ZnO薄膜形貌,结构和光学性能进行了研究.SEM图表明CdS量子点已成功沉积到ZnO薄膜上,量子点呈颗粒状,直径约71 nm.XRD结果显示,除观察到原有的ZnO特征峰外,在2θ=30.3°处有一明显的特征峰,对应着CdS的(111)晶面.PL谱图表明在325 nm的光激发下,CdS量子点敏化ZnO薄膜在400 nm处有一较强的紫外发射峰,在500～700 nm处有一个较宽的黄绿发射带.吸收光谱表明,CdS量子点敏化后ZnO薄膜在可见光区的吸收边为586 nm.     

聚丙烯酸电解质准固态染料敏化TiO2太阳能电池

以聚丙烯酸为电解质取代传统的液体电解液制备了准固态染料敏化TiO2太阳能电池.该电池具有较好的光电转换性能,在60mW/cm2的模拟光照下(AM1.5),短路电流Isc和开路电压Voc分别为91.5μA/cm2和520mV,光电转换效率和填充因子分别为0.06;和0.63.     

ZnO/TiO2复合光阳极染料敏化太阳能电池的研究

采用醇热法制备ZnO纳米粉体,采用水热法制备TiO2纳米粉体,将不同质量分数的ZnO与TiO2混合制备浆料,采用刮涂法在掺氟的SnO2透明导电玻璃(FTO)上制备ZnO/TiO2纳米复合薄膜光阳极,与Pt对电极和电解质组装成染料敏化太阳能电池.采用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)和扫描电镜(SEM)对所制备的样品进行表征,通过光电性能测试和电化学阻抗谱测试,研究了添加不同质量分数的ZnO对电池性能的影响.结果表明:不添加ZnO纳米粉时,纯TiO2光阳极的电池光电转换效率为7.95;,而添加了2wt; ZnO的ZnO/TiO2复合光阳极电池的效率达到9.54;,比纯TiO2电池的效率提高了20;.     

电化学沉积制备二氧化钒反蛋白石光子晶体

通过电化学沉积方法向PS胶体晶体模板缝隙中填充五氧化二钒,焙烧去除模板后,在真空度小于10-2Pa,温度510℃下退火12 h,得到具有特定应用价值的二氧化钒反蛋白石(opal)光子晶体.用扫描电镜观察样品的微观形貌,用X射线衍射分析样品成份.实验结果表明,通过电化学沉积制备出的二氧化钒反蛋白石光子晶体,相变电阻突变数量级在2～3之间,相变温度62℃左右.     

水浴温度对CdS薄膜性能的影响

采用化学水浴法,以不同水浴温度在玻璃衬底上沉积CdS薄膜并制备CIGS薄膜太阳能电池,研究了水浴温度对CdS薄膜和CIGS太阳能电池性能的影响.结果表明:水浴温度对CdS薄膜的致密性、沉积速率、透过率和成分比率都有影响.在65-80℃之间制备的CdS薄膜均匀致密且透过率高,可作为CIGS太阳能电池的缓冲层;另外,CdS缓冲层的厚度对CIGS电池的性能影响显著,较薄的CdS缓冲层能够增加CIGS电池在400-500 nm波段对光线的吸收,提高CIGS电池的短路电流.     

Yb3+-Ho3+-F-共掺杂TiO2纳米晶的上转换发光性能及其在染料敏化太阳能电池中的应用

采用溶胶-水热法制备了Yb3-Ho3+-F-共掺杂的TiO2(简写为UC-F-TiO2)纳米粉末.通过XRD,TEM,拉曼光谱,XPS和发光光谱,研究了yb3掺杂浓度对UC-F-TiO2纳米粉末的结构、形貌和上转换发光性能的影响规律.结果表明:UC-F-TiO2纳米粉末颗粒的大小约20 nm,由金红石和锐钛矿两种结构混合组成,且随着yb3+掺杂浓度的增加,金红石结构的TiO2所占比例增加;在980 nm激光激发下,UC-F-TiO2发射出中心在543 nm、647 nm和751 nm处的三个发光带.研究了基于UC-F-TiO2和纯TiO2纳米多孔薄膜光阳极的染料敏化电池的光伏性能.结果表明:与纯TiO2制备的电池相比,将UC-F-TiO2应用于染料敏化电池,电池的光电转换效率提高了29.7;.     

Development of Pauling's concepts of geometric characteristics of atoms

The evolution of the geometric characteristics introduced by Pauling and their dependence on the specific features of the structure and chemical bonds have been considered. The values of the covalent and van der Waals radii are given as well as their relationships and mutual transitions.     

Relationship of Morphological Types of Dynamic Forms of Crystals

Crystallography Reports - The relationship of morphological spectra (sets of data on the morphological types of real polyhedral crystals and their probabilities under current physicochemical...     

A SAXS study of kinetics of aggregation of silica sols

SAXS in situ experiments on the evolution of TMOS solutions during hydrolysis and polycondensation lead to power laws with scaling exponents ≈ 2. It is suggested that this could be the result of the polydispersity of the samples and that only an apparent fractal dimension can be obtained in this way. Kinetic studies tend to indicate that agglomeration in the sol is the result of a diffusion-controlled process.     

Study of the possibility of interactive control of the surface profile of X-ray optical elements

We investigate the possibility of controlling the curvature parameters of parabolic mirrors that are modular elements of two types consisting of a base and thin inserts placed at the opposite side of the work surface. In the first type of modular elements, bending is controlled by the difference in the coefficients of the thermal expansion of the base and inserts. In the second type of elements, the profile is changed by the piezoelectric straining of the inserts under an electric field. A correlation is established between the parameters of modular elements and their surface curvature profile.     

A review of measurement of thermophysical properties of silicon melt

Measurements of thermophysical properties of Si melt and supplementary study of X-ray scattering/diffraction by the authors' group were reviewed. The values obtained differed variously from those of literature. Density was 2–3% larger, surface tension 20–30% smaller, viscosity up to 40% larger, electrical conductivity 8% smaller, spectral emissivity more or less in good agreement with literature values, and thermal diffusivity a few percent larger. An anomalous density jump was found near the melting point. Surface tension and viscosity also showed anomaly. A strange time-dependent change of density was observed over 3 h after melting. X-ray analyses suggested a slight change in local atom ordering, but showed no sign of cluster formation. An addition of 0.1 at% gallium caused the density jump to disappear, while that of boron caused no change. An EXAFS study of the former melt indicated a strong interaction between Ga and Si atoms as if molecules of GaSi₃ existed. The implications of the measured properties are a possibility of soft-turbulence in an Si melt in a relatively large crucible, a more complicated manner of intake of oxygen depleted molten Si from the free surface region to underneath the growing crystal, and a relaxation of the melt after melting arising from trapped gas species.     

Mechanism of thermal expansion of structural modifications of zinc pyrovanadate

Crystal chemical characteristics of the α and β modifications of Zn₂V₂O₇ are calculated based on in situ high-temperature X-ray measurements. The expansion of the structure is found to be strongly anisotropic up to the negative volumetric thermal expansion of the α-Zn₂V₂O₇ unit cell in the temperature range of 300–600°С, α _V =–17.94 × 10^–6 1/K. The transformations of the “hard” and “soft” sublattices with an increase temperature and at the phase transition are considered in detail. It is shown that the negative volumetric thermal expansion of α-Zn₂V₂O₇ is due to the degeneracy of the zigzag-like shape of zinc–oxygen columns at constant distances between their vertices.     

Generation of crystal structures of heteromolecular compounds by the method of discrete modeling of packings

Within the method of discrete modeling of packings, an algorithm of generation of possible crystal structures of heteromolecular compounds containing two or three molecules in the primitive unit cell, one of which has an arbitrary shape and the other (two others) has a shape close to spherical, is proposed. On the basis of this algorithm, a software package for personal computers is developed. This package has been approved for a number of compounds, investigated previously by X-ray diffraction analysis. The results of generation of structures of five compounds—four organic salts (with one or two spherical anions) and one solvate—are represented.     

Dependence of the parameters of equations of viscous flow on chemical composition of silicate melts

The temperature dependence of viscosity of silicate melts is discussed in the framework of the Avramov–Milchev (AM) equation. The composition is described by means of two parameters: the molar fraction, x, and the “lubricant fraction”, l. The molar fraction is the sum of the molar parts x_i of all oxides dissolved in SiO₂, the molar fraction of the latter being 1 ? x. It is shown that, with sufficient precision, two of the parameters of the AM equation can be presented as unique functions of the molar fraction. On the other hand, x is not sufficient to determine properly the reference temperature T_r , at which viscosity is η_r = 10¹³ [dPa.s]. Therefore, additional parameter, “lubricant fraction” l, is introduced. For each of the components, l_i is a product of molar part x_i and a specific dimensionless coefficient 0 ≤ k_i ≤ 1 accounting for the specific contribution of this component to the increased mobility of the system. It is demonstrated that, for l > 0, the reference temperature is related to the “lubricant fraction” l through the reference temperature T_r,SiO2 of pure SiO₂.     

Comparative analysis of two methods of calculation of the orientation of domain walls in ferroelastics

Two types of domain-wall equations are analyzed: the equations derived by the Sapriel method and the equations obtained by interface matching of the thermal-expansion tensor. It is shown that, for W-type domain walls, these methods yield the same equations. For W′-type domain walls, the equations obtained by different methods coincide for proper ferroelastics and differ for improper ferroelastics.     

Investigation of the Mechanism of Influence of Stress Corrosion on the Development of Macroplastic Instabilities of Aluminum–Magnesium Alloy

Crystallography Reports - Macroscopic jumps of plastic deformation (few percent in amplitude) on creep curves of aluminum–magnesium alloy, caused by a local effect of concentrated solution of...