籽晶层对氧化锡纳米棒生长质量及其钙钛矿太阳能电池性能的影响

利用SnCl2·2 H2 O和SnO2纳米粒子为籽晶层前驱体分别生长SnO2纳米棒,并作为电子传输层制备钙钛矿太阳能电池(PSCs).综合利用场发射扫描电子显微镜(SEM)、X射线衍射仪(XRD)、紫外可见近红外分光光度计(UV-vis)、稳态光致发光光谱(PL)和伏安特性曲线(J-V)等表征技术,分析研究籽晶层前驱体对SnO2纳米棒薄膜和钙钛矿薄膜的形貌、结构、光学性质、SnO2/钙钛矿界面间的电荷转移能力以及电池性能的影响规律.结果表明:SnO2纳米粒子相比SnCl2·2 H2 O能够形成更致密的籽晶层,从而更易于生长出平整、均匀的SnO2纳米棒薄膜.沉积于以SnO2纳米粒子为籽晶层的SnO2纳米棒上的钙钛矿有源层具有更好的结晶质量和更强的光吸收性能,所制备电池的最高效率达到12.93％.本工作表明SnO2纳米粒子是一种优异的生长SnO2纳米棒薄膜的籽晶层材料,为制备高性能的基于一维电子传输材料的钙钛矿电池奠定了一定基础.     

叠层式TiO2/SnO2复合纳米薄膜制备及其光电性能研究

采用溶胶-凝胶法在不同基体表面制备了叠层式TiO2/SnO2复合纳米薄膜.用扫描电子显微镜(SEM)、X射线衍射(XRD)对复合薄膜表面形貌和晶体结构进行表征.采用紫外-可见吸收光谱法和电化学方法来研究复合薄膜光学与光电化学性能特征.结果表明,所制备的叠层式TiO2/SnO2复合纳米薄膜表面连续、均匀、致密;XRD分析表明纳米TiO2为锐钛矿型结构,SnO2为金红石型结构;紫外-可见吸收光谱测试表明叠层式TiO2/SnO2复合纳米薄膜较纯TiO2薄膜的吸收范围拓宽;稳定电位随时间变化曲线(OCP-t)结果表明,叠层式TiO2/SnO2复合纳米薄膜光照下其光电化学性能高于纯TiO2薄膜;同时,光照后叠层式TiO2/SnO2复合纳米薄膜能有效储存TiO2先生电荷,延续对不锈钢基体的光生阴极保护性能.经比较,叠加3层SnO2的TiO2/3SnO2复合纳米薄膜改善光电性能最佳.     

SnO_2基陶瓷的制备及其性能研究

以纳米SnO2粉末为原料制备导电陶瓷,研究了所制备的SnO2-Sb2O3-CuO三元系SnO2基陶瓷的烧结性能和导电性能。用光学显微镜、扫描电镜和X射线能谱仪等对陶瓷基体的相组成和微观组织进行了分析。结果表明,纳米SnO2粉末在加入一定量的Sb2O3和CuO添加剂后,烧结活性有所提高;加入烧结助剂CuO可明显促进SnO2的烧结;在最佳CuO-Sb2O3配比下,制备的SnO2基陶瓷的综合性能良好。     

溶胶-凝胶法制备纳米SnO2微晶生长的电镜表征

利用溶胶-凝胶法制备纳米SnO2粉体中发生的团聚和微晶生长现象与加热时间和加热温度有直接的关系.利用透射电子显微镜对四种不同制备条件下生成的纳米SnO2粉体观察可以发现凝胶前驱物水解后形成的SnO2微晶尺度在5纳米以下.这些微晶随加热时间长短发生不同程度的团聚,当加热温度高于400℃时团聚的微晶开始重新结晶生长,在600℃全部生长为块状单晶,并可以观察到生长形成的枝晶.本工作结对为溶胶一凝胶法制备纳米SnO2的工艺改进提供了理论依据.     

活性模板法制备纳米铜粉体

采用活性模板法制备了高纯纳米铜（Cu）粉体。研究了超声波频率、焙烧温度对纳米粉体性能的影响，通过X射线衍射（XRD）、透射电子显微镜（TEM）和激光粒度分析仪等手段对样品的成分、形貌、粒度及其分布进行了分析。结果表明，模板介质炭黑具有微反应器作用、空间位阻效应和较强的还原性，模板法制得的纳米Cu粉呈规则的链状球形，无明显团聚体，平均粒径为32．3nm，粒径分布窄，粒径范围在19．4～49．5nm。     

磁控气化回收SnO_2陶瓷电极的技术研究

本文提出一种高效回收SnO2陶瓷电极的技术,采用磁控气化回收的方法将SnO2电极制成复合纳米粉末,实现废电极的回收再利用。借助BET(比表面积)、XRD(X射线衍射)和SEM(扫描电子显微镜)等技术对粉末进行表征,结果表明,所回收制备的SnO2复合粉末颗粒形貌呈类球形,平均粒径dBET在100 nm左右。XRD结果表明,未经热处理的粉末晶粒结构为四方金红石型SnO2结构,其中存在极少量SnO,经900℃热处理后,只存在单一四方金红石型SnO2结构。     

滤纸模板法制备纳米SnO2及其在太阳能电池中的应用

以SnCl4为原料,定量滤纸为模板,通过浸渍和煅烧制备纳米SnO2材料,并将其应用于染料敏化太阳能电池;通过X射线衍射仪、扫描电子显微镜和透射电子显微镜检测样品的组成和结构,采用电化学工作站测试电池性能及内部阻抗。结果表明,SnCl4浓度为1.0 mol/L时,可得到高纯度和结晶度的枝连结构纳米SnO2,基本颗粒粒径为30 nm,组装电池具有相同条件下最佳电荷传输性能,且光电转换效率为1.51%。     

ZnO纳米复合粒子的制备及紫夕吸收性能研究

利用乙醇辅助水热法制备出ZnO／TiO2和ZnO／SnO2两种纳米复合粒子,采用X射线衍射（XRD）、扫描电子显微镜（SEM）及x射线能谱（EDS）分析方法对其结构进行表征,并通过紫外-可见漫反射光谱（uvvis）分析探讨了其紫外可见吸收性能,研究结果表明,在紫外-可见漫反射吸收光谱图中,ZnO／TiO2和ZnO／SnO2纳米复合粒子的最大吸收峰较纯纳米ZnO蓝移。同时,在可见光波段也有较弱吸收,拓展了其紫外吸收光谱。     

掺杂效应对氧化锡纳米晶微结构与性能的影响

采用配合物前驱体化学法制备了颗粒分布均匀,性质稳定的SnO2纳米微粒.通过XRD, HRTEM分析表明该方法制备的Rh掺杂SnO2纳米晶具有明显的包覆结构,粒径较未掺杂体系纳米晶的粒径小.通过对两纳米晶体系的紫外图谱研究,发现Rh掺杂后SnO2纳米晶的激子峰和吸收带边均发生红移现象,并对这一新异的光学特性进行了解释.     

Sol-Gel法制备纳米SnO2掺杂PMMA透明复合材料

采用溶胶-凝胶法制备SnO2的乙醇溶液胶体,在140℃条件下,获得乙醇修饰的无定形纳米SnO2,将该纳米SnO2溶于甲基丙烯酸甲酯(MMA)单体中,聚合制备得到SnO2/PMMA复合材料.采用X衍射(XRD)、傅立叶红外(FTIR)、示差扫描量热-热重法联用(DSC-TG)、粒度仪和透射电镜(TEM)等方法对纳米SnO2、纳米SnO2乙醇溶液及其SnO2/PMMA复合材料进行分析表征.扫描电子显微镜(SEM)对实验获得的透明的SnO2/PMMA复合材料进行了分析,表明纳米SnO2能够较好的分散在PMMA中.     

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.     

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。     

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.     

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.     

掺杂Bi_2Ti_2O_7对Y_2O_3-2TiO_2系微波介质陶瓷材料性能的影响

目前国内外对εr范围在40～80左右的中介电常数微波介质陶瓷体系的研究还很缺乏。为适应现代微波通讯技术发展需求,本实验研究开发了新型中介电常数Y2O3-2TiO2系微波介质陶瓷,并在此基础上添加Bi2Ti2O7陶瓷粉料进行复相掺杂。利用网络分析仪,阻抗分析仪,XRD,SEM等方法,本文重点研究了不同Bi2Ti2O7掺杂量对Y2O3-2TiO2系微波介质陶瓷材料烧结性能和介电性能的影响。通过分析发现适量掺杂能够有效降低材料的烧结温度,并使材料致密化。同时由于Bi3+置换主晶相中的Y3+形成了固溶体,材料主晶相为烧绿石结构并未改变。当添加质量分数为8wt%时获得介电性能较好的陶瓷材料,烧结温度从未掺杂的1460℃降低到1320℃。在1M下:εr≈62.14,tanδ≈1.22×10-3,微波频率(4.55GHz)下εr≈62.85,Q.f=4122.8GHz,τf=-7ppm/℃。     

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.