纳米 KTi6O13w合成中的形态演化和生长机理

以纳米TiO2为原料，通过煅烧反应制备了纳米K2Ti6O13晶须，对晶须合成中温度和时间诱导的相变、形态演化和生长机理等进行了原位研究．结果表明;纳米TiO2作原料可显著降低晶须合成温度，适宜的煅烧温度为900-1100℃．形态演化观察和高温XRD分析表明；K2Ti6O13晶须的相变及生长对温度极为敏感，形态演化是基于初期爆发式的相变和随后串并联式的长大．K2Ti6O13晶须的生长遵守本研究提出的串并联机制，晶须轴向的生长台阶是串并联生长的直接结果．     

聚苯胺/(蒙脱土-纳米纤维素)三元复合电极材料的制备及电化学性能

采用冷冻干燥法制备蒙脱土-纳米纤维素(MTM-CNFs)复合基底材料,再通过原位聚合,无模版法构建有序纳米阵列线结构,合成了聚苯胺(PANi)三元复合电极材料.对其微观结构、合成机制、电导率及电化学性质进行了分析,研究了一维线性材料、二维片状材料与导电聚合物的复合机制及无模版法制备PANi阵列储能材料的方法.结果 表明...     

Ni-Zn铁氧体纳米晶的机械化学合成

以α－Fe₂O₃、ZnO及NiO粉体为原料,在高能球磨的作用下,通过机械化学反应合成了Ni－Zn铁氧体纳米晶．用XRD、TEM及Mossbauer谱学方法对样品进行了表征．结果表明,球磨所得纳米晶的晶粒尺寸为5～20nm,表现为超顺磁性．经800℃热处理后,晶粒长大到约50nm;表现为亚铁磁性．     

纳米结构Bi2Te3基热电材料的溶剂热合成

本文评述了近年来溶剂热合成纳米结构Bi2Te3的研究进展，重点讨论了合成过程中的化学反应和晶体生长机制，特别是Bi2Te3纳米管的合成、形成机制和组织结构特征．介绍了含纳米结构Bi2Te3的Bi2Te3基同质纳米复合结构热电材料，其热电优值ZT达到1．25，远高于基体材料，也超过目前的块状先进Bi2Te3基热电材料．     

回流法制备纳米 NiZn铁氧体及成相机理研究

采用回流法合成了纳米级的尖晶石相NiZn铁氧体．通过XRD测试和回流液反应过程中pH值变化分析，确定了最佳的回流反应时间为6h，同时对回流反应的机理进行了初步的研究．透射电镜结果显示NiZn铁氧体的颗粒为10-30nm，高分辨透射电镜分析表明回流法合成的铁氧体为单一尖晶石相．用VSM研究了纳米NiZn铁氧体粉料的软磁特性．     

CdTe@Fe3O4磁性复合纳米粒子的合成与表征

本文通过层层自组装技术（1ayer-by—layer,LBL）成功制备了CdTe@Fe3O4磁性荧光复合纳米粒子,并对其特性和应用进行了讨论．首先,采用化学共沉淀法,以NaOH为沉淀剂,Fe^2＋和Fe^3＋物质的量的比为1：2．在50℃水相中电磁搅拌30min,制备出具有磁性的纳米Fe3O4,然后表面修饰1,6-己二胺．通过透射电镜（transmission electron microscopy,TEM）对其进行观察,粒径在10nm左右．核壳cdTe@Fe3O4复合功能纳米粒子的合成表明：Fe3O4和cdTc物质的量的比为1：3,pH=6．0,温度30℃,反应时间30min为其最佳合成条件．通过TEM、紫外和荧光光谱对合成的纳米粒子分别进行了表征．cdTe@Fe3O4粒径在12～15nm,最大发射波长从530nm红移到570nm,而最大吸收波长则从530nm红移到535mm．结果表明,磁性Fe3O4表面成功覆盖了CdTe壳层．核壳型CdTe@Fe3O4磁性荧光复合纳米粒子的应用能够实现对DNA进行简便快捷的标记、传感和分离．     

纳米K2Ti6O13W合成中的形态演化和生长机理

以纳米TiO2为原料,通过煅烧反应制备了纳米K2Ti6O13晶须,对晶须合成中温度和时间诱导的相变、形态演化和生长机理等进行了原位研究.结果表明:纳米TiO2作原料可显著降低晶须合成温度,适宜的煅烧温度为900～1100℃.形态演化观察和高温XRD分析表明:K2Ti6O13晶须的相变及生长对温度极为敏感,形态演化是基于初期爆发式的相变和随后串并联式的长大.K2Ti6O13晶须的生长遵守本研究提出的串并联机制,晶须轴向的生长台阶是串并联生长的直接结果.     

碳包覆铁纳米颗粒制备及电磁性能分析

以纤维素为基质,硝酸铁为金属颗粒前躯体,在氢气保护下进行控温炭化合成出准球形的碳包覆铁纳米颗粒．产物通过TEM、EDX和XRD表征呈核壳结构,粒径分布比较窄．通过波导法对所制备的碳包覆铁纳米颗粒进行吸波性能分析,采用矢量网络仪研究分析其在8．2～12．4GHz频率范围内的电磁性能．     

多臂 CdS纳米晶体的水热控制合成

以络合剂为辅助剂，用水热方法合成了多臂CdS纳米晶体，用TEM、ED、SEM、RAMAN、PL等技术对产物进行了表征．研究了不同络合剂对水热合成多臂CdS纳米晶体的影响，以乙二胺、甲胺、乙胺为辅助剂水热合成所得三臂CdS的产率分别为2％、35％、85％，而以氨为辅助剂时，仅能得到颗粒状CdS纳米晶体．此外，对水热合成多臂CdS纳米晶体的形成机制作了初步探讨．     

采用碳纳米管制备的碳化硅纳米晶须研究

本文报道了采用两步生长法生成碳化硅（SiC）纳米晶须.首先通过二氧化硅与硅反应生成一氧化硅,然后生成的SiO与碳纳米管先驱体反应生成立方结构的β-SiC纳米晶须．其直径为3～40nm,长度为2～20μm．通过XRD、HREM、Raman、PL等检测手段,对生成的碳化硅纳米晶须的形貌、结构等进行了分析研究．其直径为3～40nm,长度为2～20μm．并具有峰值位于430nm的蓝光发射带,本文中还对碳化硅纳米晶须生长机制进行了讨论．     

水热法合成4A沸石的相变/纳米聚合生长过程及其机理研究

用廉价的硅铝系渣料为原料,通过水热法合成了4A沸石,根据不同时间的晶化反 应产物,用XRD、SEM等表征手段对4A沸石的形成机理及晶体长大过程进行了研究,结果 表明:①该反应过程的机理属前驱体固相→硅酸根或铝酸根液相→P型沸石晶相→P型沸石 向A型沸石的相变→A型沸石向P型沸石逆相变;②4A沸石晶体的长大是通过纳米聚合生 长的结果.     

Emulsion-derived urchin-shaped hydroxy sodalite particles

Urchin-shaped hydroxy sodalite (HS) particles composed of numerous nanorods of 400-500 nm in length with hexagonal cross-section of 50-100 nm in diameter were synthesized following non-ionic surfactant-stabilized water-in-oil (w/o) emulsions at a considerably low temperature of 90⁰C with a short duration, 10 h. The non-ionic surfactant, i.e. sorbitan monooleate (Span 80) of hydrophilic-lipophilic balance (HLB) value of 4.3 was found to be suitable for the preparation of emulsions. Crystalline phases and microstructures of the synthesized particles were studied by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) respectively. A relatively lower synthesis temperature (80 °C), under the same reaction conditions, resulted in the formation of thread-ball-like particles of HS along with a little amount of cubic NaA zeolite particles while flower-like HS particles were obtained at 100 °C. A tentative mechanism for the formation of HS particles of different morphologies was proposed. The HS particles find important use as seed crystals for the preparation of ceramic membranes in the separation technology and catalysis in various reactions.     

Effective manipulation of the microstructure of zeolite film by hydrothermal pretreatment

Zeolite films with diverse microstructures were prepared from highly regular seed monolayers by accurate manipulation of various synthetic parameters during secondary growth. The effects of the hydrothermal pretreatment procedure, hydrothermal pretreatment temperature and duration, secondary growth temperature and duration of prepared zeolite films on final microstructures were investigated in detail. Based on these results, a mechanism was proposed to elucidate the effects of hydrothermal pretreatment on the secondary growth dynamics of the zeolite films: hydrothermal pretreatment could induce the separation of secondary nucleation and the subsequent growth process. Consequently, the disordered growth of zeolite films could be effectively avoided.     

Coral-like hydroxy sodalite particles from rice husk ash as silica source

Coral-like hydroxy sodalite (HS) particles were prepared from rice husk ash as silica source in the presence of other aqueous-based precursor materials following a simple process under hydrothermal condition at 90 °C for 15 h. The particles obtained at 90 °C for different times (6, 10 and 15 h) were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). The HS crystals along with a small amount of zeolite A particles were observed at 90 °C/6 h while phase pure HS particles were obtained at 90 °C for 10 and 15 h. The characteristic vibration bands of the HS particles were confirmed by FTIR spectroscopy. FESEM images showed that the HS particles obtained at 90 °C/15 h were coral-like morphology which were formed through the self-assembly of the smaller particles generated at the initial stage of reaction (6 and 10 h) under the same experimental conditions. A proposed mechanism for the formation of coral-like HS particles was also illustrated.     

A novel technique for fabrication of rod-like shape zeolite LTA and hydroxysodalite by extrusion of bentonite powder: Effects of technical factors on structural characteristics

The current investigation proposes a novel method for the fabrication of zeolite-based packed beds by extrusion of a paste, containing Ca-bentonite, boehmite, and sodium hydroxide, as rod-like shape. The formed precursor was heated at 800 °C to reinforce the extrudates, aged at different times, 3–24 h, and converted to the zeolite structure by recrystallization in the hydrothermal condition, 3–9 h. The obtained results showed that aging, and recrystallization times affect the crystalline phase structure, morphology of particles, textural properties, and cation exchange capacity (CEC) as characterized by X-ray diffractometry, field emission electron microscopy, and N₂ adsorption–desorption isotherms. The thermally treated extrudates could be converted to zeolite LTA, and or hydroxysodalite (HS), depending on aging, and recrystallization times. It is necessary to age the treated extrudates in 9 h, and control the recrystallization time within 3 h to achieve zeolite LTA with a proper CEC, 232 mg g⁻¹. Contrarily, the choice of inverse conditions, leads to create a mesoporous HS with a broad pore size distribution, 2–50 nm.     

载银沸石对纸张抑菌防霉性能及 印刷适性的影响

研究了不同添加质量(或添加质量浓度)的载银沸石对牛皮纸、白卡纸和铜版纸的抑菌防霉效果及机械性能、白度、平滑度等印刷适性的影响。结果表明:1)当纸张中载银沸石的添加质量浓度为1000mg/L时,大肠杆菌的抑菌环直径达21.5mm,由此可知,载银沸石能较好地抑制大肠杆菌的生长。2)当纸张中载银沸石的添加质量为1.0g时,纸张完全无霉菌生长,且纸张边缘的菌丝也未见长出,由此可知,载银沸石对黑曲霉具有一定的抑制效果。3)不同添加质量的载银沸石对纸张的机械性能、白度和平滑度有一定影响,但影响较小。故当载银沸石的添加质量为0.5～1.0g时,纸张不仅具有较好的抑菌防霉效果,且其机械性能、白度和平滑度没有明显变化。     

Effective utilization of waste ash from MSW and coal co-combustion power plant: Zeolite synthesis

The solid by-product from power plant fueled with municipal solid waste and coal was used as a raw material to synthesize zeolite by fusion-hydrothermal process in order to effectively use this type of waste material. The effects of treatment conditions, including NaOH/ash ratio, operating temperature and hydrothermal reaction time, were investigated, and the product was applied to simulated wastewater treatment. The optimal conditions for zeolite X synthesis were: NaOH/ash ratio=1.2:1, fusion temperature=550 degrees C, crystallization time=6-10 h and crystallization temperature=90 degrees C. In the synthesis process, it was found that zeolite X tended to transform into zeolite HS when NaOH/ash ratio was 1.8 or higher, crystallization time was 14-18 h, operating temperature was 130 degrees C or higher. The CEC value, BET surface area and pore volume for the synthesized product at optimal conditions were 250 cmol kg(-1), 249 m(2) g(-1) and 0.46 cm(3) g(-1) respectively, higher than coal fly ash based zeolite. Furthermore, when applied to Zn(2+) contaminated wastewater treatment, the synthesized product presented larger adsorption capacity and bond energy than coal fly ash based zeolite, and the adsorption isotherm data could be well described by Langmuir and Freundlich isotherm models. These results demonstrated that the special type of co-combustion ash from power plant is suitable for synthesizing high quality zeolite, and the products are suitable for heavy metal removal from wastewater.     

Transformation behaviour of zeolite A to hydroxysodalite in batch and semi-batch crystallizers

Many useful molecular sieve zeolites are known to be metastable in their hydrothermal synthesis environments. This property frequently results in their undesirable transformation to less useful, but more stable, crystalline phases. The metastable transformation of molecular sieve zeolite NaA to hydroxysodalite (HS) in hydrothermal systems was studied in order to understand these phenomena better. Transformations were studied in relation to initial batch compositions in both batch and semi-batch crystallizers.The results indicate that the rates of these metastable transformations depend on the relative compositions of the reagents (silica, alumina, soda) and the absolute reagent content. The total residual reagent content relative to the amount of water present must be sufficiently high to promote hydroxysodalite nucleation once the relative reagent compositions are in the proper ratios. Therefore, in some cases the transformation of NaA to HS might never occur, and undesirable contamination of a zeolite product may be avoided. This Paper also investigates why the batch and semi-batch crystallizers perform differently insofar as metastable phase transformations are concerned.     

Crystallization of ZSM-5 zeolite under microgravity

Crystal growth of ZSM-5 zeolite under microgravity was carried out using a Soviet reentry system. The space-grown zeolite was composed of grains of uniform shape and size (ca. 10 μm). Most of zeolite grains were linked with each other by the edge of the grain. The electron diffraction of each grain showed a single-crystal diffraction pattern, indicating the presence of well-crystallized zeolite crystal. The relatively large difference in the surface Al concentration existed between different crystals of the space-grown zeolite, as compared with the zeolite crystals synthesized in the ground with stirring. Based on these results, the crystals growth of zeolite in the microgravity environment was discussed.     

Seeded growth of beta zeolite membranes using zeolite structure-directing agent

In this work, beta zeolite membranes were prepared on seeded α-Al₂O₃ substrate tubes using zeolite structure-directing agent (ZSDA), instead of directly using organic agent as templates. This ZSDA method consists of two steps: preparation of beta ZSDA and growth of beta zeolite membranes with ZSDA by the secondary hydrothermal synthesis. The molar compositions of the synthesis solution of ZSDA and zeolite membrane are of 1SiO₂/0.012Al₂O₃/0.167(TEA)₂O/0.031Na₂O/9.4H₂O and 1SiO₂/0.03Al₂O₃/0.027(TEA)₂O/0.27Na₂O/25H₂O, respectively. Preparing the membranes only needed a little ZSDA, which was used to substitute for conventional templates in the secondary growth process of the membrane. The membranes were characterized by SEM, XRD and nitrogen permeance. It was found that the prepared membranes are continuous and defect-free. The mechanism of membrane growth with ZSDA was discussed simply.