In2O3 nanoparticles synthesized by mechanochemical processing

In₂O₃ nanoparticles were synthesized by a mechanochemical reaction (InCl₃ · 4H₂O + NaOH) with NaCl as a diluent and subsequent calcination, producing In₂O₃ nanoparticles (26.7 nm) at 500 °C for 1 h. The size of the nanoparticle increases with increasing calcination temperature.     

Sb2S3纳米线的制备和表征

以硫化钠(Na2S)和氯化锑(SbCl3)为原料,采用水热法在240 ℃下反应12 h 制备了大量高长径比的Sb2S3纳米线.X射线粉末衍射测试结果表明,所制备的产物是正交Sb2S3晶相,其晶胞参数为:a=1.123 nm,b=1.131 nm,c=0.3840 nm.通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)和高分辨透射电镜(HRTEM)分析表明:所制备的Sb2S3纳米线为单晶并且沿[001]晶面生长,其直径为100～250 nm,长为100 μm.初步讨论了Sb2S3纳米线的生长机制.     

仿生法沉积Sb2S3微晶薄膜

以硫脲(SC(NH2)2)和三氯化锑(SbC13)为主要原料,采用仿生法在玻璃基板上制备了Sb2S3薄膜,研究了热处理温度对薄膜晶相、显微结构和禁带宽度等的影响.采用X-射线衍射仪(XRD)、原子力显微镜(AFM)和紫外-可见自记式分光光度计等对薄膜的相组成、显微结构和光学性能进行了表征.结果表明300℃热处理后获得的薄膜为无定形薄膜;随热处理温度的提高,薄膜的结晶性能变好,薄膜生长和取向性增强;随着热处理温度从300℃提高到500℃,薄膜的光学带隙由2.06 eV降低到1.88 eV.     

Vaporization kinetics of Sb_2S_3 in argon fluid

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Preparation of colloidal Sb_2O_5 and its stability

1　INTRODUCTIONColloidalantimony pentoxideisanewinorganicflameretardant .Itcanbeusedinrubber,plastics,fiber ,textile ,carpet,paint ,paperandprintedcircuitboardbe causeofitsflameretardingabilityandotherexcellentpropertiessuchashighdispersion ,lowcoloringintensityandhighheat stability[15] .Althoughmoreandmoreap plicationsofcolloidalantimonypentoxidearefoundintheindustry,therearelackofdetailedstudiesonprepara tionandstabilityofcolloidalantimonypentoxideex ceptsomepatentsabouttechnologicalproc…     

杂化Cu2O/Cu纳米粒子的水相合成及强化光降解甲基橙的催化活性研究

为了优化Cu2O纳米粒子的光催化性能,论文以抗坏血酸作为还原剂、聚乙烯吡咯烷酮为表面活性剂采用水相合成的方法通过调控反应温度制备出杂化Cu2O/Cu纳米粒子。利用SEM、XRD和N2吸附技术对Cu2O/Cu纳米粒子的形貌特征和结构性能进行表征。同时,也研究Cu2O/Cu纳米粒子催化降解甲基橙(MO)的效果和降解反应动力学。实验结果表明,制备的杂化Cu2O/Cu纳米粒子为“鹅卵石”形状,粒径尺寸范围在20至40nm之间,与纯Cu2O粒子相比相比,杂化Cu2O/Cu粒子具有尺寸小、比表面积大的特点。由于杂化材料中引入了Cu纳米粒子,促进了Cu和Cu2O和之间的界面电荷转移,使得Cu2O/Cu纳米粒子展现更优异的催化性能。Cu2O/Cu催化降解MO的反应符合一级动力学反应模型。经过四次循环使用后,杂化Cu2O/Cu仍然能表现出良好的催化活性。     

Preparation of Sb2O3/Sb2S3/FeOOH composite photoanodes for enhanced photoelectrochemical water oxidation

A novel Sb₂O₃/Sb₂S₃/FeOOH photoanode was fabricated via a simple solution impregnation method along with chemical bath deposition and post-sulfidation. The X-ray diffractometry, Raman measurement, and X-ray photoelectron spectroscopy show that the Sb₂O₃/Sb₂S₃/FeOOH thin films are successfully prepared. SEM−EDS analyses reveal that the surface of Sb₂O₃/Sb₂S₃ thin films becomes rough after the immersion in the FeCl₃ solution. The optimized impregnation time is found to be 8 h. The FeOOH co-catalyst loaded Sb₂O₃/Sb₂S₃ electrode exhibits an enhanced photocurrent density of 0.45 mA/cm² at 1.23 V versus RHE under simulated 1 sun, which is approximately 1.41 times compared to the photocurrent density of the unloaded one. Through the further tests of UV−Vis spectroscopy, the electrochemical impedance spectra, and the PEC measurements, the enhancement can result from the increased light-harvesting ability, the decreased interface transmission impedance, and the remarkably enhanced carrier injection efficiency.     

Preparation and formation mechanism of Al2O3 nanoparticles by reverse microemulsion

Al2O3 nanoparticles were prepared by polyethylene glycol octylphenyl ether（Triton X-100）/n-butyl alcohol/cyclohexane/ water W/O reverse microemulsion. The proper calcination temperature was determined at 1 150 ℃ by thermal analysis of the precursor products. The structures and morphologies of Al2O3 nanoparticles were characterized by X-ray diffraction, transmission electron microscopy and UV-Vis spectra. The influences of mole ratio of water to surfactant on the morphologies and the sizes of the Al2O3 nanoparticles were studied. With the increase of surfactant content, the particles size becomes larger. The agglomeration of nanoparticles was solved successfully. And the formation mechanisms of Al2O3 nanoparticles in the reverse microemulsion were also discussed.     

Growth of single crystal GaAs nanowires by a surface diffusion-mediated solid-liquid-solid process

A facile route to synthesize GaAs nanowires by simply heating Au-coated GaAs substrates to 700 °C under vacuum (～10 ^?3 Torr) was developed in this study. Detailed structural analyses showed that ultrathin single crystal GaAs nanowires with an average diameter of ～15 nm were grown outward from the Au metal droplets remaining on the surface of the GaAs substrate. On the other hand, the substrate surface region contacting the metal layer became porous, and the depth of the porous layer increased with increasing processing time. Based on these results, it was concluded that the nanowires were grown by a solid-liquid-solid process involving the surface diffusion of adatoms from the underlying solid substrates to the Au liquid droplets.     

Characterization and sintering of BaZrO3 nanoparticles synthesized through a single-step combustion process

Barium zirconate (BaZrO₃) nanoparticles synthesized by a self-sustained single-step combustion process is reported in this paper. In this process, a phase pure nanopowder of BaZrO₃ has been obtained by the combustion of an aqueous solution containing Ba and Zr ions by using citric acid as complexing agent and liquor ammonia as fuel, thus giving rise to phase pure BaZrO₃ nanopowder in a single-step combustion without any further calcination. The X-ray diffraction studies have shown that the as-prepared powder was single phase, crystalline, and has a cubic perovskite structure (ABO₃) with a lattice constant a = 4.19 Å. The average particle size calculated from FWHM is 30 nm. The phase purity of BaZrO₃ nanopowder has been examined using differential thermal analysis (DTA), thermo gravimetric analysis (TGA) and Fourier transform of infrared spectroscopy (FTIR). The transmission electron microscopic investigation has shown that the particle size of the as-prepared powder was in the range 30–50 nm with a mean size of 40 nm. The nano BaZrO₃ has been sintered to a density of 99% of the theoretical density at 1650 °C in 2 h without the use of any sintering aids. The morphology of the sintered pellets has been studied with scanning electron microscopy (SEM). The dielectric constant (_r) and loss factor (tan δ) values obtained at 10 MHz for a well-sintered barium zirconate pellet has been found to be 32.2 and 1 × 10⁻⁴, respectively, at room temperature.     

非均相沉淀-热还原法制备金属镍包裹氧化铝球形微粉

利用非均相沉淀包裹技术，在室温下的水溶液中，以球形碱式碳酸铝铵（AACH）、硫酸镍和碳酸氢铵为原料，制备了金属镍包裹氧化铝球形微粉前驱体，即碱式碳酸镍（NCH）包裹碱式碳酸铝铵微粉。然后，将前驱体在500℃下用氢气还原，成功制备了表面光滑、致密的金属镍包裹氧化铝球形微粉。研究了在非均相沉淀过程中，被包裹碱式碳酸铝铵微粉粉体浓度、硫酸镍和碳酸氢铵加料速度、反应时间、表面活性剂等因素对复合粉体前驱体制备的影响，利用SEM、EDS、XRD等手段表征了复合粉体前驱体及还原产物的表面及切面形貌、成分和结构。     

Growth of uniform ZnO nanoparticles by a microwave plasma process

ZnO nanoparticle coatings with a controlled size distribution have been grown on quartz substrates by a novel microwave plasma assisted spray (MPAS) technique. This study presents the analysis of structure, photoluminescence, and magnetic properties of particle coatings with two distinctly different mean particle sizes (400 nm and 200 nm). X-ray diffraction patterns show a typical wurtzite structure without any impurity phases for the nanoparticle coatings. SEM and TEM investigations have shown the grown nanoparticles to be spherical and well separated with a narrow size distribution. Nanoparticles are polycrystalline with smaller grain sizes associated with the smaller particle sizes. Photoluminescence (PL) spectra reveal the presence of oxygen vacancy related defects in the 400 nm nanoparticles, which become less pronounced in the 200 nm nanoparticles. The 400 nm nanoparticles are found to exhibit room-temperature ferromagnetism with a clear hysteretic behavior, while the 200 nm nanoparticles are diamagnetic even down to 10 K. These results suggest the oxygen vacancies were the cause for defect-induced ferromagnetism in the 400 nm nanoparticles.     

Mechanical and thermoelectric properties of Zn4Sb3 and Zn4Sb3+Zn directly synthesized using elemental powders

Direct synthesis using elemental powders has been used to produce single-phase polycrystalline ε-Zn₄Sb₃ specimens as well as composite specimens having ε-Zn₄Sb₃ (majority phase) and Zn (minority phase). The effect of the Zn phase on the elastic, thermoelectric and mechanical properties was investigated in this alloy system. Thermoelectric properties of single-phase Zn₄Sb₃ at an ambient temperature are comparable to the published data for the sample prepared by a hot-pressing of ingot-melted alloy powders. Transport properties at room temperature were also evaluated. In addition, Young’s modulus and the bulk modulus of polycrystalline Zn₄Sb₃ were measured using a resonant-ultrasonic technique. The fracture toughness in this alloy system was determined by measuring the length of cracks that formed at the corners of pyramidal indentations used for hardness tests. It is shown that the addition of Zn increases the fracture toughness, but this is achieved at the cost of reducing the thermoelectric figure of merit.     

Decoration of In2O3 nanowires with BaTiO3 nanoparticles for enhancement of magnetic properties

We have fabricated the composite nanowires consisting of In₂O₃ core and BaTiO₃ shell, via a two-step method. The BaTiO₃ shell has been deposited on core In₂O₃ core nanowires by means of pulsed laser deposition technique. X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy were employed to analyze the structure and morphology of the products. While SEM confirmed that the products maintained the one dimensional morphology, the shell layer corresponded to the nanoparticles of the hexagonal BaTiO₃ phase. With bare In₂O₃ nanowires exhibiting weak ferromagnetism, the ferromagnetic behavior was enhanced by decorating the In₂O₃ nanowires with BaTiO₃ nanoparticles. The shell coating enhanced the ferromagnetic behavior at both 5 and 300 K, in terms of the increase of coercive field, remanent magnetization, and saturation magnetization values in the hysteresis curves. We suggested that the generation of BaTiO₃ nanoparticles and oxygen vacancies during the high-temperature shell coating process played a role in enhancing the ferromagnetic properties of the nanowires.     

Structural dependence of the piezoelectric properties of KNbO3 nanowires synthesized by the hydrothermal method

Because of the presence of OH^? and H₂O in the KN unit cell, tetragonal KNbO₃ (KN) nanowires were formed when the synthesis was carried out at 120 °C for 48 h. However, when the fabrication was conducted at high temperatures (?150 °C) or at 120 °C for a long period of time (?72 h), orthorhombic KN nanowires were formed. Moreover, the KN nanowires synthesized at 120 °C for 60 h showed a morphotropic phase boundary (MPB) structure in which both tetragonal and orthorhombic structures coexisted. Tetragonal, orthorhombic and MPB KN nanowires were also grown on the Nb⁵⁺-doped SrTiO₃ substrate, and their d₃₃ values were measured for the first time. A tetragonal KN nanowire exhibited a d₃₃ value of 23.5 pm V^?1, which is larger than that of the orthorhombic KN nanowire (11.6 pm V^?1), probably because of the softening effect of the metal vacancies. The MPB KN nanowires exhibited a larger d₃₃ value of 40.0 pm V^?1. The d₃₃ values of KN nanowires increased to 104.5, 137.1 and 146.0 pm V^?1 for the orthorhombic, tetragonal and MPB KN nanowires, respectively, after the KN nanowires were poled along the [1 0 0] direction by application of a DC voltage of 10 V.     

钛片真空热氧化制备二氧化钛纳米线

对经过不同预处理的钛片进行真空热氧化处理,在表面原位制得了TiO<,2>纳米线.利用场发射扫描电子显微镜(FE-SEM)、高分辨透射电子显微镜(HR-TEM)和X射线衍射仪(XRD)对原位制备的TiO<,2>纳米线的表面形貌及相结构进行表征,并通过降解水中染料罗丹明B的方式对经不同时间热氧化处理后酸洗钛片的光催化性能进行测试.薄膜结构表征结果表明,一定真空条件下钛片750℃热氧化5～10 h后可以获得大量直径40～50 am,长度3.0～5.0 μm的单晶金红石结构TiO<,2>纳米线;使用H<,2>O<,2>氧化钛片表面预先获得一层多孔非晶TiO<,2>薄层显著影响纳米线的生长.光催化性能测试结果表明,真空热氧化处理1 h获得的扁平片状纳米结构金红石具有最高的光催化降解罗丹明B的能力;处理时间从5 h延长到10 h,得到的纳米线金红石薄膜的光催化性能提高.     

Study of the kinetics of space charge formation in colloidal magnetic nanoparticles in liquid dielectrics

The relaxation time of a near-electrode space charge in magnetic colloids based on dielectric liquids is experimentally established via electrooptical methods as being in the range of 0.05–0.3 s depending on the conductivity of the sample. The results agree with the data of the electrosurface effect in magnetic colloids.     

Growth and structural properties of pulsed laser-ablated CuInSe2 nanoparticles by pulsed-laser ablation and selenization process

Nanoparticles of CuInSe₂ (CIS) were synthesized by pulsed laser ablation. The effect of the preparation conditions on the structural properties of the CIS nanoparticles was investigated. The CIS nanoparticles showed a more developed structural property after treatment in Se-evaporated atmosphere. By X-ray photoelectron spectroscopy, increase of Se amounts in the CIS nanoparticles was confirmed. Enhancement of phonon modes in the CIS nanoparticles was observed in Raman scattering spectroscopy while secondary phases like In₂Se₃ or CuAu structure-related peak were identified in the spectra. High-resolution transmission electron microscopy indicated that the individual nanoparticles were embedded in matrix of some amorphous layers and diffraction patterns representing the chalcopyrite structure were also scrutinized.