SnO2纳米微晶的合成及气敏性分析

采用溶剂热技术分别在油酸体系及无水乙醇体系中成功地合成了球形和菱形的 Sn O2 纳米微晶。通过X-射线粉末衍射、选区电子衍射、透射电镜和比表面积测定等手段对合成产物的结构进行了表征 ,并对合成产物的气敏性进行了分析。结果表明 :含有精细结构的球形 Sn O2 纳米微晶的比表面积为 1 4 6 m2· g-1,灵敏温度为 1 6 0℃左右 ,适合于作气敏元件材料     

SnO2纳米晶的水热合成及其气敏特性

SnO2 nanocrystal with different crystalline sizes were prepared with SnCl2 2H2O and H2O2 raw materials by a hydrothermal process. The synthesized powders at different reaction temperatures were characterized by means of powder X-ray diffraction, transmission electron microscope, specific surface area and gas sensitivity measurements. The results revealed that the pure SnO2 nanocrystallites synthesized at 120 ℃ have high specific surface area （210.3 m2/g）, and show a high sensitivity to C2H5OH gas. Both traits are beneficial in gas-sensitive detection application.     

溶剂热合成具有海绵状结构的介孔SnO2

采用溶剂热方法, 以SnCl4·5H2O/尿素/乙醇三元体系合成了具有特定结构的前驱体, 该前驱体经焙烧后得到了具有海绵状结构的介孔SnO2. 利用X射线粉末衍射(XRD)、傅立叶红外吸收光谱(FT-IR)、透射电镜(TEM)、热分析(TG-DTA)和氮气等温吸附鄄脱附等方法对产物的结构、形貌和热稳定性进行表征. 结果表明, 300 ℃焙烧处理后的样品由粒径约为5 nm的纳米粒子堆积而形成海绵状结构, 其中孔的尺寸范围在2-8 nm, 样品比表面积达到了134 m2·g-1.     

纳米铁酸锌的水热合成

利用水热合成法制备纳米铁酸锌粉体，使用XRD、TEM研究了铁酸锌晶相组成、粒度大小和形貌，并对影响合成工艺的因素如反应前驱物的pH、反应温度、反应时间与产物的关系进行系统的考察研究。结果表明：前驱物的最佳pH为11－12，反应温度为448K，反应时间为360min，可制得结晶良好、纯度高、分散性好、粒度为纳米级的ZnFe2O4粉体。     

纳米级掺锑SnO2导电粉体的水热合成及性能研究

高纯二氧化锡是一禁带宽度达3·8eV的绝缘体,当产生氧空位或掺杂氟、铟、锑等元素后形成N型半导体,具有导电性能。常用于这些领域的N型半导体有掺铟氧化锡(ITO)、掺锑氧化锡(ATO)、掺铝或掺镓氧化锌(AZO、GZO)。由于ATO的机械性能和热稳定性比ITO高,作为抗静电材料广泛应用于涂     

Ⅲ-Ⅴ族半导体纳米粒子合成的进展

半导体科学技术是现代信息技术的基础，Ⅲ－Ⅴ族半导体纳米材料受垤广泛的重视。采取有机液相合成方法是制备Ⅲ－Ⅴ话半导体纳米粒子的重要途径。本文综述了近几年合成Ⅲ－Ⅴ话半导体纳米粒子的进展情况。     

球形SnO2 纳米微粒的合成及形成机理分析

以SnCl4*5H2O为主要原料,用溶剂热技术在油酸体系中成功地合成了球形SnO2纳米微粒,在无水乙醇体系中合成了菱形的SnO2纳米微粒.通过X射线粉末衍射(XRD),选区电子衍射(SAED)和透射电镜(TEM)对两种产物进行了表征,并对两种产物的形成机理进行了分析.透射电镜(TEM)结果表明: 在油酸体系中得到了平均尺寸约为 3.5 nm的球形SnO2纳米微粒,此微粒趋向于特殊高的比表面积,适合于作气敏探测器材料方面的应用.     

纳米钛酸钡的水热合成进展

综述了水热合成纳米钛酸钡的影响因素、发展现状及存在的问题，并指出其发展趋势。参考文献57篇。     

Na2SO4辅助水热合成SnO2纳米晶

系统地研究了以SnCl₄·5H₂O为原料，以Na₂SO₄为矿化剂，采用水热法在较低温度下和较短的反应时间内制备结晶良好并均匀分散的SnO₂纳米晶。采用X射线衍射(XRD)、透射电子显微镜(TEM)、红外光谱(IR)等技术对水热反应的晶化过程进行了分析。结果表明：在Na₂SO₄存在的情况下，在120 ℃反应4 h 即可制备得到晶粒细小，分散性能良好的SnO₂纳米晶。XRD衍射峰峰宽随水热温度的升高或反应时间的延长而变窄，结晶性提高。TEM结果表明产物颗粒小、分散性能良好。水热反应温度和反应时间对产物结晶度和粒径有明显的影响。对Na₂SO₄在反应过程中的作用机理进行了分析。     

纳米SnO2@TiO2包覆催化剂的制备及表征

采用活性层包覆法在自制细SnO2胶体粒子表面包覆TiO2,制备出SnO2@TiO2包覆型复合催化剂,以其对有机磷农药DDVP的降解效果作为评价光催化活性的标准,对制备条件进行了优化,并用XRD、TEM和BET等手段对样品进行了表征,结果表明,SnO2胶体乙醇溶液含水量20％,钛酸丁酯质量分数为34.5％。灼烧温度680℃时制得TiO2含量56.45％的包覆样品SnO2@TiO2为纳米级粒子,且其光催化活性最佳。     

Synthesis and Gas-sensing Performance of Nanosized SnO2

Nanosized tin dioxide particles were prepared by sol-gel dialytic processes with tin(Ⅳ) chloride and alcohol as start materials. The nanoparticles of tin dioxide were charactered by thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET. The results show that the average diameter of tin dioxide particles dried at 353 K was about 2nm. Even if the tin dioxide particles were calcined at 873 K, the average diameter of particles was less than 10 nm. The removal of Cl^- was solved by using this kind of method. The mechanism of the formation of tin dioxide nanosized particles was proposed and analyzed in this paper. We also measured the sensitivity of the sensor based on the tin oxide powder calcined at 673K to NH3, alcohol, acetone, hexane and CO. The gas-sensing performance results indicate that this sensor has a higher sensitivity to alcohol and acetone, and selectivity for NH3, hexane and CO at an operating temperature of 343 K.     

Mn和Fe掺杂SnO2的水热合成与磁结构研究

采用水热法合成了Sn1-x-yMnxFeyO2(0≤x≤0.10, 0≤y≤0.10)稀磁半导体. 通过XRD, Raman, TEM, SQUID和Mössbeaur等技术对化合物进行了结构和性能的表征. 结果表明, XRD中没有出现第二相的沉积, Raman光谱中出现了Mn位于SnO2晶格中的局域模式. 磁性测试结果表明, 当x=0.10, y=0时, 样品在低温下具有较强的磁化强度, 但室温下其磁化强度急剧降低. 而y=0.10, x=0时, 样品的磁化强度和矫顽力都比较小, 但随温度的改变变化不大, Mössbeaur谱测试结果表明, 其中的Fe一部分是铁磁耦合的, 拟合得到超精细场和同质异能移等参数表明, 铁磁性来源于Fe替代SnO2本征性能. Mn和Fe共同掺杂的样品的磁化强度随x的减少和y的增加而减少, 矫顽力却相对于单一元素掺杂的样品大大增加.     

纳米晶氧化锡的水热合成与表征

以水热法合成了高比表面积的纳米晶SnO_2粉体，运用FT-IR，XRD，BET，TEM 等手段对粉体的晶化过程进行了分析表征。FT-IR显示120 ℃水热得到的粉体即实 现水合锡化合物的晶化。XRD分析表明所得粉体均匀数纳米，且随水热温度的提高 ，晶粒长大。水热粉体均具有很高的比表面积。TEM显示粉体呈单分散状态。将水 热粉体进行热处理，粉体则长大较快，比表面积降低，分散性能出现反常改善。     

水热法制备稳定的发光CdTe材料

采用水热合成技术将表面修饰有羧基的纳米CdTe微粒与表面活性剂和硅源进行自组装,得到了一种与氧化硅复合的稳定的CdTe发光材料.通过一系列表征手段(如TG-DTA,EDX,TEM,荧光光谱和N₂吸附)证实了CdTe微粒复合在氧化硅中.进一步通过烧结的方法除去表面活性剂,用稀酸除去金属氧化物,即得到多孔的氧化硅材料.     

The Role of Hydrothermal Synthesis in Preparative Chemistry

“Hydrothermal synthesis” usually refers to heterogeneous reactions in aqueous media above 100°C and 1 bar. The previously common distinction between hydrothermal conditions below and pneumatolytic conditions above the critical point is no longer made, since no discontinuities are observed upon exceeding the critical conditions. Under hydrothermal conditions, reactants otherwise difficult to dissolve go into solution as complexes, in whose formation water itself or very soluble “mineralizers” can participate. Thus, one can obtain the conditions of chemical transport reactions,^[1] of which hydrothermal syntheses can be considered a special case. During recent decades in the geological sciences—in which the method is also historically rooted—it has received a strong impulse, whose effect on preparative solid state chemistry is discussed here.     

Synthesis of carbon-supported Pd/SnO_2 catalyst for highly selective hydrogenation of 2,4-difluoronitrobenzene

Halogenated anilines have a wide range of applications in the production of pharmaceuticals and agrochemical substances, and thus it is of great importance to develop highly active and selective catalysts for the hydrogenation of halogenated nitrobenzenes. We approach this challenge by probing noble metal/non-noble metal oxide nanoparticles(NPs) catalysts. Carbon-supported Pd/SnO2catalysts were synthesized by the chemical reduction method, and their catalytic activity was evaluated by the hydrogenation reaction of 2,4-difluoronitrobenzene(DFNB) to the corresponding 2,4-difluoroaniline(DFAN), showing a remarkable synergistic effect of the Pd and SnO2 NPs. The as-prepared Pd/SnO2/C catalysts were characterized using TEM, XRD, H2 TPD and XPS techniques. Modifications to the electronic structure of the Pd atoms through the use of SnO2 led to the suppression of the hydrogenolysis of the C–F bond and the acceleration of nitrosobenzene(DFNSB) conversion and consequently, resulted in the inhibition of the formation of reactive by-products and may be responsible for the enhancements observed in selectivity.     

Synthesis of SnO_2 nanorods from aqueous solution:The effect of preparation conditions on the formed patterns

<正>SnO_2 nanorods were deposited on the Si substrates in an aqueous solution containing both SnCl_4 and CO(NH_2)_2.It is found that different self-assembled patterns of SnO_2 nanorods can be obtained by changing the deposition conditions such as the molar ratio of CO(NH_2)_2 to SnCl_4 and the pretreatment of the substrate.Scattered SnO_2 nanorods,for example,can be changed into flower-like patterns when the molar ratio of CO(NH_2)_2 to SnCl_4 is raised,and well-aligned nanorod arrays can be formed when the pretreatment of the substrate is changed.In addition,some interesting patterns,e.g.tree-like patterns,can also be observed.     

MoS2的水热合成及其润滑性能

利用水热合成法在相对较低的反应温度(200 ℃)和较短的反应时间(24 h)内合成了MoS2.采用透射电子显微镜(TEM)、X射线光电子能谱(XPS)和X射线衍射(XRD)分析了合成的纳米MoS2的结构.同商品MoS2（平均颗粒直径为3～5 μm）进行了摩擦学性能对比，并利用俄歇电子能谱(AES)深度剖析和XPS分析了MoS2作为润滑剂在钢磨损表面的粘着成膜作用及润滑机理.结果表明,该水热合成的产品具有较商品MoS2更低的摩擦系数，适合在大载荷、长时间工作状况下使用.     

纳米 ZSM-22分子筛的水热合成及在甲醇转化反应中的性能

分子筛结构的独特性和多样性使其在催化、吸附分离和离子交换等领域有着广泛应用.近年来,纳米分子筛制备和应用受到极大关注.与传统微米分子筛相比,纳米分子筛具有较小的晶粒尺寸、较大的外表面积和较高的表面活性,能显著提高其分离和催化性能.制备纳米晶体的常用方法有过量模板法、空间限定法、晶种法、离子热合成法及微反应器合成法等.目前,已合成出多种拓扑结构的纳米分子筛,包括 FAU, MFI, MEL和CHA等. ZSM-22是一种具有 TON拓扑结构的一维十元环直孔道分子筛(孔口尺寸为0.45 nm ×0.55 nm),在长链烷烃异构化和烯烃异构化等反应中表现出优异的催化活性.水热合成法是制备 ZSM-22分子筛最常用的方法,所得样品晶粒尺寸为2–15μm,但由于 ZSM-22分子筛是一种亚稳态结构,为了防止杂晶生成,合成通常是在剧烈搅拌(通常大于400 r/min)下进行.目前已有报道在较低转速下合成 ZSM-22分子筛,但产物仍为微米晶体;或在微波辅助水热合成条件下合成亚微米 ZSM-22分子筛,但晶体尺寸不可调且合成过程需要较高功率的微波反应器.因此,在水热条件下合成纯纳米 ZSM-22分子筛仍然是一个巨大挑战.本文在上述研究基础上采用改进的水热合成法成功合成出纳米 ZSM-22分子筛,考察了转速﹑硅铝比及乙醇共溶剂对晶粒尺寸的影响,比较了纳米和常规微米 ZSM-22分子筛的甲醇转化反应性能.结果表明,采用改进的水热合成法能够在较低转速下合成出纳米 ZSM-22分子筛,晶体尺寸在150–800 nm范围可调.通过考察转速对晶粒尺寸的影响,发现静态合成条件下无法形成 ZSM-22分子筛,表明 ZSM-22分子筛合成需要一定的转速.转速在10–50 r/min变化时,可以合成出不同晶体尺寸的 ZSM-22分子筛,且随转速提高, ZSM-22分子筛晶体尺寸先减小后增大,表明纳米 ZSM-22分子筛合成存在最佳转速.另外,配料硅铝比能显著影响 ZSM-22分子筛晶体尺寸,随配料硅铝比增加, ZSM-22分子筛晶体尺寸先减小后增大.通过在合成体系中添加乙醇作为共溶剂,考察了有机溶剂对 ZSM-22分子筛晶粒尺寸的影响,发现有机溶剂能显著增大 ZSM-22的晶体尺寸.将本文合成的纳米和常规微米 ZSM-22分子筛用于甲醇转化反应,考察了晶体尺寸对 ZSM-22分子筛甲醇转化反应性能的影响.发现与常规微米 ZSM-22分子筛相比,纳米 ZSM-22分子筛催化剂寿命显著提高,说明晶粒尺寸减小能有效减缓积碳导致的分子筛失活;同时,反应产物中乙烯和芳烃选择性有所提高,这是由于外表面积增大所致.此外,还考察了不同硅铝比 ZSM-22分子筛的甲醇转化反应性能.结果表明,分子筛硅铝比会影响催化剂寿命,但晶体尺寸对催化剂寿命影响更大. ZSM-22分子筛硅铝比增大有助于提高低碳烯烃选择性,减少芳烃生成.     

Hydrothermal Synthesis,Crystal Structure,and Thermal Stability of Two New Metal Phosphonates with a Pillared Layered Structure

Two new metal phosphonates with a 3D pillared layered framework based on N,N′‐piperazinebis(methylenephosphonic acid), H₂O₃PCH₂NC₄H₈NCH₂PO₃H₂ (H₄L), Sn[O₃PCH₂NHC₄H₈NHCH₂PO₃] ( 1 ) and Pb₃(OH)₂[O₃PCH₂NC₄H₈NCH₂PO₃] ( 2 ), have been synthesized under hydrothermal conditions and structurally characterized by single‐crystal X‐ray diffraction as well as with infrared spectroscopy, elemental analysis and thermogravimetric analysis. For compound 1 , each ψ‐square pyramidal SnO₄ unit is in turn corner‐shared by four CPO₃ tetrahedral from four different phosphonate ligands to form two‐dimensional inorganic puckered layers in ab planes. In compound 2 , the complicated inorganic layer (bc planes) is built up of ψ‐PbO₄N, PbO₆ and CPO₃ polyhedra. The overall structure for two compounds may be described in terms of alternating inorganic infinite layers and organic pillars {CH₂N(C₂H₄)₂NCH₂}, to form a 3D pillared layered structure.