Papers by Keyword: Growth Mechanism

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Authors: Liang Xu, Chuan Zhen Huang, Han Lian Liu, Bin Zou, Hong Tao Zhu, Jun Wang
Abstract: The TiB2 whiskers were fabricated in TiB2/TiCx composites by the in-situ synthesis process. The phase composition, thermodynamics, weight loss and lattice parameters of the obtained phases were studied. The obtained TiB2 whiskers showed an aspect ratio of 10-20 and a diameter of 0.5-1.5 μm. The synthesized TiC was a non-stoichiometric phase with a lattice parameter of 4.274 Å. Most of the whiskers had the cylinder shape, whereas, a few whiskers showed a bead-necklace morphology. The growth mechanisms of TiB2 whiskers were governed by the solid-liquid-solid (S-L-S) mechanism and the particle-to-particle connection mechanism.
Authors: De Gao Zhong, Bing Teng, Ming Li, Qing Guo Wang, Yan Shuai Zhao, Fei You, Hui Xu, Shi Ming Zhang
Abstract: A kind of in-situ crystal growth observation system for solution temperature reduction method was designed. The growth surface morphology of KDP crystal was observed by this system. Dislocation hillocks with elliptical shape were clearly distinguished on the {100} face. The dynamics process of morphology evolvement on growth surface of KDP crystals was recorded and analyzed. The growth velocity of the step trains generated from dislocation hillocks was about ~10-4.
Authors: Wu Feng Jiang, Su Ju Hao, Yun Han Ling, Jun Sheng Liao
Abstract: Titanium dioxide nanotube array films on aluminum plate were prepared via liquid phase deposition (LPD) method. The samples were characterized by field-emission scanning electron microscopy (FE-SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). The results show that the nanotube array films’ morphology depends on the anodic aluminum oxide (AAO) structure and deposition time. The titanium dioxide nanotube’s outside diameter is about 250 nm, the wall thickness is approximately 40 nm. The as-prepared TiO2 array films are amorphous and anatase appeared after calcining at 400°C for 2 hrs. FT-IR spectrum indicates that there are lots of hydroxyl groups on the surface of AAO. When AAO was immersed into 0.1 M (NH4)2TiF6 solution at room temperature, AAO was dissolved in the solution and the holes became wide. The hydrolysis reaction was shifted to the right-hand side, TiO2 particles locked in-situ on the inner surface of the anodic alumina pore induced by hydroxyl group, thus nanotube array film was obtained.
Authors: Hui Chung Hsueh, Zue Chin Chang, Chang Ching You, C. B. Lin
Abstract: Abstract: This investigation develops a novel method for fabricating silver chloride films by the heterogeneous precipitation of sodium chloride from aqueous solution and supersaturated solid-state silver nitrate out of aqueous solution. The morphology of the bottom surface of the silver chloride film thus obtained comprises numerous porous stick structures. The top surface comprises equiaxed grains, and columnar grains are observed in the cross-section.
Authors: Jian Qiang Li, Wei Pan, Rui Gang Wang, Jian Chen
Authors: Xi Zhong An, Guo Quan Liu, Chao Li
Abstract: The growth of nano CVD diamond films on low index faces such as (111) face and (100) face under different proposed surface chemical reaction model was simulated by using Kinetic Monte Carlo (KMC) method from atomic scale. The results, for example the influence of deposition time t, substrate temperature Ts, and atomic hydrogen concentration [H] on the film deposition rate, surface roughness, and H embedded in the film under different processing conditions, were systematically analyzed and compared. And the adsorption of various species on {111}-oriented diamond cluster was preliminarily computed from electronic scale by Local Density Approximation (LDA) method to assist understanding the surface adsorption mechanism. It is indicated that the film morphology and quality obtained from atomic scale KMC simulation varies according to the chemical reaction models. And our initial electronic scale computation on {111}-oriented diamond cluster showed that single-carbon species can be adsorbed on the activated site more easily than double-carbon species and the former will result in a more stable state than the latter. In order to reveal the nano CVD diamond film growth mechanism, more work about various species adsorption on many different morphological CVD diamond surfaces is needed.
Authors: Anne Marie Huntz, S.C. Tsaï, J. Balmain, K. Messaoudi, Bernard Lesage, C. Dolin
Authors: Qiu Xiang Wang, Qian Zhang, Li Feng Dong
Abstract: Carbon fibers with different morphologies are obtained using different cupric solution precursors (e.g., cupric sulfate, cupric nitrate, and cupric chloride) at various temperatures. The morphology of carbon fibers depends on the type of catalyst precursor and reaction temperature but not the concentration of the precursor solution. For example, cupric chloride solution is a desirable catalyst precursor for the growth of carbon fibers with multi-branches at 450 °C. However, a mixture of carbon sheets and linear fibers forms at 300-350 °C. The splitting mode can be used to explain the formation of carbon fibers with different morphologies at various reaction temperatures.
Authors: Qiao Ling Li, Yong Fei Wang, Cun Rui Zhang
Abstract: One-dimensional (1D) hematite (α-Fe2O3) nanorods have been successfully prepared using a chemical precipitation method. The sample was characterized by using a variety of techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The results showed that the nanorods obtained were monocrystalline, with an average diameter of about 60nm and a length of up to 800nm. In the preparation of α-Fe2O3, the length of α-Fe2O3 seemed to increase with the addition of polyethylene glycol (PEG), and the diameter seemed to decrease with the addition of Zn2+. Nanorods of α-Fe2O3 with a smaller diameter and superior slenderness ratio were prepared by adding both PEG and Zn2+. A possible growth mechanism effect of PEG and Zn2+ upon the morphology of α-Fe2O3 was as follows: α-FeOOH grew in a one-dimensioned orientation upon the surface of a polyethylene glycol template. In the meantime, the Fe3+ position in the α-FeOOH crystal was substituted by Zn2+; resulting in point defects in α-FeOOH crystal due to the radius discrepancy between Zn2+ and Fe3+. The growth-step energy was then reduced as a result of the point defects in the α-FeOOH crystal. The results of magnetic measurements of the hematite nanorods revealed a weak ferromagnetic property which might be related to the shape anisotropy.
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