共查询到16条相似文献,搜索用时 93 毫秒
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以硝酸铝为原料,氨水为沉淀剂,得到一水软铝石(γ-A lOOH)沉淀。以该一水软铝石为前驱物,纳米α-氧化铝为晶种,采用水热法直接制备出α-氧化铝微粉。在保温时间为8 h、反应温度从380℃增加到460℃时,水热合成的α-氧化铝微粉的粒径从2.1μm生长到3.5μm;在400℃下,保温时间从8 h增加到36 h时,其粒径从2.3μm增加到4.6μm。据此得出α-氧化铝晶粒生长符合动力学方程:Dn=Dn0 k0.t.e(-Ea/RT),其中晶粒生长指数n=2,活化能Ea=47.37 kJ/mol。分析了α-氧化铝晶体生长机理。 相似文献
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采用超声辅助微弧氧化复合工艺在钛合金表面制备了钙磷生物涂层。采用扫描电镜和电子能谱仪测试了涂层表面形貌和元素组成,分析了超声辅助微弧放电特性,建立了MAO系统等效电路,提出了复合工艺所制备涂层的Ti O2相氧化机制及钙磷相合成机制。结果表明:复合工艺提前了微弧放电时间,降低了起弧电压,增加了有效微弧放电时间;钙离子主要通过电源脉间等效电熔放电和超声作用提高电泳活性并吸附于阳极,并与磷酸根离子反应生成钙磷生物相;配置工作液时要求钙、磷应有较大比值,且工作液中钙离子和磷酸根离子浓度应增大。研究对超声辅助微弧氧化复合工艺制备高性能钛合金生物涂层具有指导意义。 相似文献
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以MgCl2·6H2O和NH4HCO3为原料,CH3COONa·3H2O为形貌控制剂,采用沉淀结晶法制备MgCO3·3H2O晶须,考察了不同添加量的CH3COONa·3H2O对晶须结晶过程和形貌的影响,并研究了晶须在该体系中的生长机制。结果表明:当体系中加入质量分数为0.23%的CH3COONa·3H2O时可以成功制备长径比约为30的棒状MgCO3·3H2O晶须,CH3COONa·3H2O的存在促进了MgCO3·3H2O晶须的形成。该体系中晶须的生长过程:首先形成无定形的4MgCO3·Mg(OH)2·4H2O,之后无定形4MgCO3·Mg(OH)2·4H2O逐渐转变为MgCO3·3H2O并生长成较大长径比的棒状MgCO3·3H2O晶须。这是因为CH3COONa·3H2O电离产生的Na +选择性吸附在MgCO3·3H2O晶体轴向的(101)晶面,抑制了该晶面生长,而径向晶面生长速率未受到影响,从而促使无定形MgCO3·3H2O生长成棒状晶须。 相似文献
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以Zn(Ac)2·2H2O、NaI和N2H4·H2O为原料,在未使用任何表面活性剂的简单水热反应体系中制得了ZnO纳米棒.采用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)对产物的晶体结构、形貌进行了表征分析,并对其光催化活性进行了探讨,以ZnO纳米棒为光催化剂对有机染料污染物甲基橙进行了光催化降解实验.实验结果表明,氧化锌纳米棒对甲基橙的光催化降解具有很好的催化作用,在紫外光照射120min后,对甲基橙的降解率接近完全. 相似文献
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铅笔状ZnO生长机理的研究及光催化性能表征 总被引:1,自引:0,他引:1
用水热法于175℃合成了铅笔状ZnO。并通过XRD、EDS、SEM、TEM和HRTEM对不同碱性条件下合成的ZnO的形貌进行了分析,结果表明,n(OH-)∶n(Zn2+)=4∶1时,ZnO的形貌为平均厚度90nm的片状结构;当n(OH-)∶n(Zn2+)=10∶1时,ZnO的形貌为直径200nm、长度2.5μm的铅笔状结构。探讨了不同形貌的ZnO的形成机理。用UV-vis吸收光谱和PL光谱分析了ZnO的形貌对次甲基蓝光催化降解的影响,结果发现,铅笔状氧化锌的光催化性能优于片状氧化锌。 相似文献
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花状氧化锌的制备与控制生长 总被引:4,自引:0,他引:4
用聚乙二醇-20000(PEG-20000),聚乙二醇-20000/环己烷为添加剂,以不同碱度的Zn(OH)42-和Zn(NH3)42+为前驱体,在200℃的水热条件下反应4 h,经洗涤、干燥处理后,得到ZnO微晶粉体. 产物用全自动X射线衍射仪(XRD)进行物相分析、扫描电子显微镜(SEM)和透射电子显微镜(TEM)观测ZnO形貌和大小. 结果表明,生成的产物属于六方晶相,是由纳米棒状单晶组成的ZnO花状集合体,组成集合体的单晶在不同反应环境中成长为粗壮、尖细、成簇等不同形貌. 0.5~4.0 mm的集合体可控制制备. ZnO集合体不是个体的简单聚集,而是由单晶分枝组成,单晶生长取向为c轴正向,各单晶以一柱状单晶中部为基准类同心生长. 研究结果对制备形貌可控的金属氧化物具有一定的参考价值. 相似文献
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《Journal of Adhesion Science and Technology》2012,26(1):102-113
AbstractWetting behavior of Zinc Oxide (ZnO) based nanomaterials has been the subject of intense investigations and is an active research field for various engineering applications and modifying the surface wettability of ZnO is of great interest. In this study, one-dimensional (1?D) semiconducting ZnO nanorods are grown on a superhydrophobic polyethylene terephthalate (PET) fabric using a hydrothermal method. A facile polydimethylsiloxane (PDMS) coating is applied onto the ZnO grown PET fabrics to improve the hydrophobicity. A wide range of characterization techniques such as field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), UV-vis spectroscopy and contact angle measurement are used to explore the morphology and wetting behavior of the as-prepared samples. The measured water contact angle (WCA) is >150° indicating its superhydrophobicity. This study reports an efficient way to obtain highly hydrophobic semiconducting ZnO grown on PET fabric, which can be of great interest for many future applications. 相似文献
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E. Savary S. Marinel H. Colder C. Harnois F.X. Lefevre R. Retoux 《Powder Technology》2011,208(2):521-525
Zinc oxide is a widely used material in various applications in electronic, optic, and spintronic fields, in particular. The control of the final properties of ZnO requires the mastering of the final microstructure. To achieve this goal, the grain growth of ZnO has been examined as a function of the sintering conditions, in particular in using a specific microwave sintering method. In order to get nano-sized ZnO powder as a starting material, a liquid route was implemented. The latter is based on the direct precipitation of a zinc oxalate solution. After thermal treatment, pure ZnO powder was obtained with a very narrow grain size distribution, centered at around 20 nm. The sintering of this powder was then carried out in conventional and microwave furnaces. While an important grain growth occurs during the conventional sintering, it is shown that microwave sintering allows us to maintain the grain size at the nano-metric scale. 相似文献
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水热法制备氧化锌陶瓷粉体中的形态调制 总被引:8,自引:0,他引:8
水热条件下制备超细微晶是一个晶体生长的过程。本文根据晶粒形态与水热介质碱度强弱之间的关系,揭示了不同形态的ZnO的形成机理,实现了水热法氧化锌陶瓷微晶制备过程中的形态调控。 相似文献
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Copper, vapor-deposited on the polar, Zn-terminated ZnO(0001) surface is investigated in view of its suitability as model
system for the technologically important Cu/ZnO catalyst. The structure and electronic properties of Cu clusters on ZnO(0001)–Zn
have been studied with scanning tunneling microscopy (STM), low energy electron diffraction (LEED), ultraviolet photoelectron
spectroscopy (UPS), and low-energy He+ ion scattering (LEIS). At room temperature copper grows as two-dimensional (2D) clusters only at very low coverages of 0.001–0.05
equivalent monolayers (ML). At coverages greater than 0.01 ML, 3D clusters start to develop. This is contrasted to Cu growth
on the oxygen-terminated ZnO(0001bar) surface, where a strong adhesion between Cu and the ZnO substrate results in an initial
wetting of the surface by Cu. On ZnO(0001)–Zn, surface roughness and sputter damage change the growth mode to more 2D-like.
Annealing in UHV results in well-separated, hexagonal clusters rotationally aligned with the substrate. Annealing of 2–5 ML
Cu deposits on the ZnO(0001)–Zn surface in 10−6 mbar O2 results in the formation of a (√3 × √3)R30° superstructure with respect to the ZnO lattice. This superstructure likely contains
Cu+ sites. The suitability of the different surface morphologies to probe specific sites that are thought to be active for catalytic
processes is discussed. 相似文献