High-resolution transmission electron microscopy investigation of nanostructures in SnO2 thin films prepared by pulsed laser deposition

Pulsed laser deposition (PLD) was used to grow nanocrystalline SnO₂ thin films onto glass substrates. The nanocrystallites and microstructures in SnO₂ thin films grown by PLD techniques have been investigated in detail by using X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). The PLD process was carried out at room temperature under a working pressure of about 2×10⁻⁶ mbar. Experimental results indicate that thin films are composed of a polycrystalline SnO₂ and an amorphous SnO phase. In particular, the presence of such an amorphous SnO phase in the thin films greatly limits their practical use as gas-sensing devices. HRTEM observations revealed that SnO₂ nanocrystallites with tetragonal rutile structure embed in an amorphous SnO matrix, which are approximatively equiaxed. These approximatively equiaxed SnO₂ nanocrystallites contain a high density of defects, such as twin boundaries and edge dislocations. The grain growth of SnO₂ thin films may be discussed in terms of the coalescent particle growth mechanism.     

微接触印刷法直接制备图案化TiO2薄膜

A novel process to gain clear and high edge acuity micropatterns of TiO2 thin films by direct microcontact printing was presented in this paper. Using TiO2 sol as the “ink”, poly (dimethylsiloxane) elastomeric stamp was taken to transfer the TiO2 colloids to the substrate. The process is different from the traditional process using the SAMS to induce the deposition of TiO2. The new way increases the transferred efficiency of the micropatterned TiO2 thin films. The optical micrographs and SEM show that the micropatterned structures of TiO2 were microscale and uniform over a large area as well.     

电沉积ZrO2—Ni功能梯度材料的组织结构分析

电沉积ＺｒＯ２┐Ｎｉ功能梯度材料的组织结构分析①全成军＊向兴华朱景川尹钟大（哈尔滨工业大学材料科学与工程学院哈尔滨１５０００１）航空航天技术的高速发展对材料的耐热性能提出了更苛刻的要求，传统的单一材料（如陶瓷、金属）和金属陶瓷复合材料已难以在超高温和...     

稀土对压铸锌合金金相组织及力学性能的影响

通过对压铸锌合金进行变质处理，研究稀土合金对压铸锌合金微观组织及性能的影响。结果表明，在压铸锌合金中加入适量的稀土，能有效地阻止α树枝状晶的长大，优化组织结构，细化晶粒，清除晶粒边界杂质，使压铸锌合金的抗拉强度和硬度提高１０％以上。同时对稀土合金元素所起的作用进行了分析讨论，为进一步改善压铸锌合金的力学性能和抗晶间腐蚀提供了一条有效途径。     

Activation,microstructure, and polarization of solid oxide fuel cell cathodes

Activation effect can be defined as the enhancement of the electrochemical performance or activity of the solid oxide fuel cell cathodes such as Sr-doped LaMnO₃ (LSM) with the polarization/current passage treatment under fuel cell operation conditions. In this paper, the activation effect of the cathodic polarization/current passage on the O₂ reduction reaction of the LSM-based cathodes is reviewed. In addition to the activation effect, cathodic polarization/current passage also has a significant effect on the microstructure of the LSM electrodes and the morphology between the LSM electrode and Y₂O₃-ZrO₂ electrolyte interface. A mechanism involving the incorporation of SrO species into the LSM lattice and the formation of oxygen vacancies is proposed for the activation effect of the polarization.     

亚麻的化学组成和微观结构对染色性能的影响

本文通过X衍射法、纤维化学成分分析法测试了亚麻纤维的微观结构、化学成分，通过对亚麻进行液氨整理改变其结晶度和取向度，从而测得亚麻的结晶度和取向度对染色性能的影响，利用碱煮、H2O2和NaOCl漂白处理降低了亚麻中木质素和半纤维素的含量，从而测量得木质素和半纤维素含量对亚麻上染率的影响。结果表明亚麻的上染率随着结晶度的降低呈线性上升，随着取向度的降低而上升；随着木质素和半纤维素含量的降低而呈上升趋势。     

The directional crystallization of W-B-C-d-transition metal alloys

Crystallization from the melt during arc melting and directional solidification during induction zone melting of pseudo-alloys tungsten carbide (WC)-MeB₂ (Me—Ti, Zr, Cr) and a number of alloys of the W-B-C system (WB_0.12C_0.74; WB_0.25C_0.75; WB_0.34C_0.32; WB_0.49C_0.76; WB_0.59C_0.76; WB_0.89C_0.75; (WC)_0.9B_0.1) has been studied. It was shown that the alloys WC—80 mass%-ZrB₂—20 mass% and WC—72 mass%-WB—28 mass% are the closest ones to eutectic compositions. Investigation of the microstructure of eutectic alloys in the WC-WB system by thin foil method has revealed that both matrix and reinforcing phases are single crystalline.Hardness tests by indentation of the eutectic structure area (P=10.3 N) do not result in radial crack formation, which is evidence of the essential plasticity of the obtained composite material. It is established that new ceramic-ceramic eutectic composite materials based on WC with transition metal diborides and with a boride phase of tungsten may be created. Such materials can be successfully applied in contemporary high-temperature techniques.     

N-vinyl-2-pyrrolidone and methacrylonitrile copolymers: nuclear magnetic resonance characterization

The copolymers of N-vinyl-2-pyrrolidone and methacrylonitrile (V/N) were prepared by free radical bulk polymerisation. The copolymer composition was determined from the quantitative ¹³C{¹H} NMR spectrum. The reactivity ratios for N-vinyl-2-pyrrolidone (V) and methacrylonitrile (N) were found to be r_V=0.04, r_N=1.56. The complete spectral assignment of the overlapped and complex carbon and proton NMR spectra were done with the help of two dimensional ¹³C–¹H Heteronuclear Single Quantum Correlation Spectroscopy (HSQC) and Total Correlation Spectroscopy (TOCSY). Distortionless Enhancement by Polarization Transfer (DEPT) was used to differentiate between the methylene, the methine and the methyl carbon resonance signals of the copolymers.     

添加Al、Mg、W、Mo对烧结Nd-Fe-B磁体磁性能与显微组织的影响

研究了在烧结ＮｄＦｅＢ磁体晶间添加Ａｌ、Ｍｇ、Ｗ、Ｍｏ等合金元素对显微组织和磁性能的影响。实验结果表明：低熔点合金元素Ａｌ、Ｍｇ能显著提高ＮｄＦｅＢ磁体的矫顽力，略微降低剩磁，对磁体的热稳定性无影响；高熔点合金元素Ｗ、Ｍｏ在不降低剩磁的情况下亦能提高磁体的矫顽力，但效果不如Ａｌ、Ｍｇ明显。显微组织分析表明，在添加低熔点和高熔点合金元素的磁体晶间发现了两种不同的新相。矫顽力的提高可归于晶间新相的出现。进一步分析表明，与传统的合金化相比，对ＮｄＦｅＢ磁体晶间区域进行微合金化是改进ＮｄＦｅＢ磁体组织与性能的一种更为有效的手段。     

Water in oil (w/o) and double (w/o/w) emulsions prepared with spans: microstructure,stability, and rheology

The objective was to analyze the microstructure, stability, and rheology of model emulsions prepared with distilled water, refined sunflower oil, and different Spans (20, 40, 60, and 80) as emulsifiers. The effects of the water content and Span 60 concentration were studied. The lowest water contents led to w/o emulsions, whereas higher percentages gave w/o/w emulsions. Microscopy analysis showed that w/o/w emulsions of higher water contents had a lower number of internal water droplets. W/o emulsions were destabilized by coalescence and sedimentation, whereas creaming was observed in unstable w/o/w emulsions. In the last ones, the creaming stability decreased with increasing water content and enhanced with higher Span 60 concentration; the same effect was observed in their viscoelasticity: They were from unstable liquids to stable gels. Solid Spans (40 and 60) produced more consistent w/o/w emulsions at low water contents and more stable systems at high water percentages in comparison with liquid Spans (20 and 80).