嵌段共聚物对SiO_2溶胶-凝胶过程的修饰行为

近年来,人们利用对溶胶凝胶(ＳｏｌＧｅｌ)化学的认识,通过表面活性剂调控硅醇盐水解缩聚反应过程和对溶胶表面进行修饰以获得在一定范围内可控结构和可控粒度的纳米材料［１,２］,但对ＳｉＯ２溶胶凝胶过程的改性机理尚待深入研究。在溶胶凝胶过程中,溶胶粒子和网络结构主要受该体系中晶核形成与生长机制以及颗粒之间作用力所控制,这是实施溶胶网络结构形貌控制的理论依据。本文考察了聚氧乙烯醚(ＰＥＯ)聚氧丙烯醚(ＰＰＯ)聚氧乙烯醚(ＰＥＯ)嵌段共聚物(简称ＥＰＥ)作为改性剂对ＳｉＯ２溶胶凝胶化过程的修饰行为,探讨了改性ＳｉＯ２溶胶…     

非水体系中电解镍中间产物制备纳米NiO

采用纯镍为阳极，乙酰丙酮和乙醇的混合溶液中加入少量有机胺导电盐为电解液，施加一定电流使镍溶解，然后将电解液直接水解，控制一定的水解条件，制备得到纳米NiO粉体. 采用拉曼光谱、红外光谱、元素分析、XRD 和TEM 分别对电解得到的纳米NiO前驱体和纳米NiO进行了分析与表征, 并探讨了电化学溶解镍金属法制备纳米NiO反应的影响因素.电化学溶解镍金属得到的前驱体为Ni(OEt)2(acac)2,这种不溶性镍醇盐配合物升温至40～50℃即可溶解于乙醇溶液中,可直接应用于溶胶 凝胶(Sol gel)过程.水解后的纳米NiO呈无定形结构, 350 ℃煅烧后形成立方晶型NaCl结构, 纳米NiO经600 ℃煅烧后粒径分布在5～10 nm. 该方法理论上为二价不溶性金属醇盐经溶胶 凝胶工艺制备纳米氧化物材料提供了一条新的途径.     

电化学法制备高热稳定性锐钛矿型纳米TiO2

以醇中加入少量有机腕导电盐作为电解液,以工业纯钛作“牺牲”阳性,控电流电解,可分别得到乙醇钛、异丙醇钛、正丁醇然等的相应醇溶液。然后直接水解,经溶胶－凝胶（Ｓｏｌ－ｇｅｌ）过程,形成凝胶前体,在４５０℃,７２０℃煅烧３０ｍｉｎ后,均得到高热稳定锐钛矿型（ａｎａｔａｓｅ）纳米ＴｉＯ２（１０ｎｍ左右）。通过ＦＴＩＲ,ＸＲＤ,ＴＥＭ等测试手段,对钛醇盐和纳米ＴｉＯ２进行了表征。本文同时讨论了不同钛醇盐制     

纳米钛酸钡生成的热分解机理

钛酸钡作为重要的铁电材料 ,多年来一直被研究者们所关注．传统方法制备钛酸钡大多采用固相法或草酸盐法得到微米级基料．随着纳米材料研究与应用的发展 ,溶胶 凝胶技术成为制备各种金属氧化物纳米材料的较普遍方法．溶胶 凝胶法制备纳米钛酸钡就是其中之一．该法一般采用钛的有机醇盐与钡盐反应生成溶胶 ,然后形成凝胶 ,再以凝胶为先体进行热处理制得纳米钛酸钡．虽然已有人对溶胶 凝胶技术制备纳米钛酸钡进行了研究 ,并对所得产物进行了表征［１,２］,但尚无人对该方法中凝胶的热分解过程作详细的研究．因凝胶的热分解过程对钛酸钡纳…     

溶胶凝胶法制备铜铁矿结构p型透明导电氧化物薄膜

铜铁矿结构p型透明导电氧化物(transparent conducting oxide, TCO)薄膜是一类在电子学领域具有广泛应用前景的新材料,因其可与n-TCO薄膜形成真正意义上的“透明器件”而备受关注。本文介绍了铜铁矿结构p-TCO的结构特性以及溶胶凝胶法的基本原理和特点;系统地介绍了溶胶凝胶法制备铜铁矿结构p-TCO薄膜的工艺;分析比较了有机醇盐、无机盐溶胶体系的优缺点;最后讨论了进一步的发展方向,指出溶胶凝胶法是一种高效可行的制备p-TCO薄膜的方法。     

金属氯化醇盐的红外光谱分析

金属氯化醇盐作为一种溶胶．凝胶法新型前驱体,其分子结构较为复杂,但关于它们结构的红外光谱分析却很少。为此,文章分别对四氯化钛和三氯化铝与乙醇、异丙醇及正丁醇的反应产物——金属氯化醇盐进行了红外光谱测试分析。结果发现,由于四氯化钛中钛的反应活性参数Rn较小,同时三氯化铝中离子键较少,因此,它们与醇之间只发生了部分亲核取代反应,导致产物中残余一定量的Ti-Cl和Al-Cl键合,即反应产物为铝、钛氯化醇盐,这样造成铝氯化醇盐的红外图谱中存在Al-Cl键合振动吸收峰,而钛氯化醇盐中C-O-Ti键合的C-O伸缩振动吸收峰峰位也明显有别于纯的金属钛醇盐。     

辣根过氧化酶溶胶-凝胶膜修饰电极与过氧化氢的安培检测

1　引　　言溶胶 凝胶法一般是以金属盐或半金属盐做前驱体 (硅酸甲酯ＴＭＯＳ、硅酸乙酯ＴＥＯＳ、钛酸丁酯等 )在水、互溶剂及催化剂的存在下发生水解和缩聚反应 ,形成ＳｉＯ2 三维网络结构。在成胶的过程中 ,若引入掺杂组分 ,可将其包埋于三维网络结构中。以二氧化硅作为传感器的工作平台 ,其优点在于它具有良好的坚固性、化学惰性、高的光稳定性和透过性 ,同时溶胶凝胶过程还具有纯度高 ,均匀性强 ,反应条件易于控制并易于实现多种产品构型等优点 ,可为各种类型生物传感器的开发和制作提供更多的机会和条件。辣根过氧化酶 (ＨＲＰ)是一…     

电化学合成金属醇盐的研究

纳米材料在生物、电子、能源、化工等各个领域的应用日益广泛 ,已成为当前研究的热点 [1,2 ] ,纳米材料的制备有多种方法 ,其中溶胶 -凝胶 ( Sol- gel) [3 ] 、醇盐热解、化学气相淀积 ( CVD)等方法所使用的前驱体主要为金属醇盐 .传统化学方法合成金属醇盐是用 MXn[X为 Hal,R,H,NR2 ,N( Si Me3 ) 2等 ]与醇进行交换反应 ,过程复杂 ,且原材料不易得到 ,产率低 ,纯度达不到要求 ,后续分离繁琐 ,所以人们一直努力寻找合成金属醇盐的新方法 .有机电解合成一般在常温常压下进行 ,可通过调节电极电位控制电极反应的方向和速度 .据报道 [4] …     

超薄硅溶胶-凝胶修饰膜的制备与表征

报道了一种制备硅溶胶－凝胶膜（sol-gel)的新方法。通过对形成溶胶和凝胶化过程的控制，获得了制备超薄溶胶－凝胶膜的最佳条件，并对膜的性质进行了一系列表征。实验表明，所得溶胶－凝胶膜具有良好的结构特征。采用光度法、电化学方法可有效地对膜的厚度进行表征。     

溶胶-凝胶法合成Li_4SiO_4

Li4SiO4具有有利于离子传导的结构,为锂离子导体理想的基质材料[1].在硅酸盐体系中,硅的聚合态很复杂,难以得到纯相,鉴于固相法操作简单,在已有的文献中,合成方法多为固相法,但固相法不易保证成份的准确性、均匀性且合成温度较高.溶胶-凝胶法是近几年来发展起来的湿化学合成方法,用此法合成离子导体具有纯度高、均匀性好、颗粒小、反应过程易于控制等优点[2],而通常的溶胶-凝胶法是用金属醇盐与有机盐为前驱物,这样成本较高,且易造成污染.本文用金属醇盐及无机盐为前驱物,用溶胶-凝胶法合成了Li4SiO4纯相,并同一般固相法相比较,对合成的…     

Sol-gel synthesis and characterization of yttria stabilized zirconia membranes

Mesoporous yttria stabilized zirconia (YSZ) membranes can be used as supports for ultrathin dense ceramic or metallic membranes, and for ultrafiltration (UF) applications in harsh environments. This paper reports synthesis and characterization of sol-gel derived UF YSZ membranes. 0.25 M zirconia sol was prepared by hydrolysis and condensation of zirconium n-propoxide. A solution-sol mixing method was used to dope 8 mol% yttria in zirconia. Supported YSZ membranes were prepared by dip-coating the yttrium doped zirconia sol on the porous α-alumina substrate, followed by drying and calcining under controlled conditions. The membranes prepared in this study are of cubic fluorite phase. Helium permeation experiments show that the supported membranes are pin-hole (or crack) free. The 5 time dip-coated membrane determined by SEM micrograph is about 3.5 μm in thickness, with an average pore diameter of 3 nm.     

乙醇在Ni-ZnO-ZrO2-YSZ阳极SOFC上的发电性能

为考察乙醇用于固体氧化物燃料电池的可行性,用柠檬酸溶胶 凝胶制备阳极催化材料Ni-ZnO-ZrO₂,利用机械混合法制备Ni-ZnO-ZrO₂-YSZ(Y₂O₃稳定的ZrO₂)阳极。用涂覆法,在YSZ电解质上,制备了Ni-ZnO-ZrO₂-YSZ/YSZ/LSM（La_0.85Sr_0.15MnO₃）与Ni-YSZ/YSZ/LSM的单体电池。在不同蒸发器操作温度、电池操作温度和乙醇蒸气流量下,以乙醇为燃料进行发电实验,对两种阳极的电池发电性能进行比较。实验结束后,用SEM检测了两种电池阳极的表面。结果表明,Ni-ZnO-ZrO₂-YSZ阳极SOFC的电池输出性能明显高于Ni-YSZ阳极,且Ni-ZnO-ZrO₂-YSZ阳极具有较好的抗积炭能力。     

Synthesis and Characterization of Yttria-Stabilized Zirconia (YSZ) Nano-Clusters for Thermal Barrier Coatings (TBCs) Applications

Yttria-stabilized zirconia (YSZ) nano-clusters were synthesized by a sol–gel process. The aim was to produce YSZ powders in order to prepare thick coatings for thermal barrier to be applied on gas turbine engine components. Yttrium nitrate hexahydrate and zirconium oxy-chloride octahydrate were used as a source of zirconium, citric acid was taken as a chelating agent, and ethylene glycol was used as a polysterification agent. The synthesized powders were characterized by X-ray diffraction, transmission electron microscopy, thermo-gravimetric analysis and differential scanning calorimetry, and Raman spectroscopy. Furthermore, parameters were critically analyzed in order to synthesize non-transformable (t′) tetragonal crystal structure, which is the best zirconia phase for high temperature thermal barrier coatings applications. In this regard, tetragonal YSZ nano-clusters were heated in an alumina crucible at a temperature of 1200 °C for 100 h.     

PCVD法制备ZrO~2和YSZ薄膜

以金属β-二酮类有机螯合物Zr(DPM)~4和Y(DPM)~3为挥发性源物质, 采用微波等离子体化学气相淀积法于较低的温度下(420～560℃)成功地在多孔α-Al~2O~3陶瓷,非晶玻璃等衬底上制备出致密的ZrO~2和YSZ薄膜材料.XRD分析结果表明,纯ZrO~2薄膜中除了单斜相外还存在着亚稳态的四方相.当掺入的Y~2O~3 摩尔百分含量大于或等于7%时,ZrO~2完全被稳定成立方相.SEM观察表明, 在等离子体内的不同区域中生成的薄膜形貌有所不同.XPS检测了YSZ薄膜中Zr3d~5~/~2和Zr3d~3~/~2 的电子结合能,发现较ZrO~2的标准值低0.7eV.由TEM观察和由XRD衍射峰半宽度计算, 所制备的ZrO~2和YSZ薄膜中微晶粒径在10nm左右     

Effect of the addition of pore former

Journal of Thermal Analysis and Calorimetry - Tetragonal zirconia (3YSZ) and cermet nickel–tetragonal zirconia (Ni/3YSZ) were obtained by citric method. The porosity of samples was increased...     

Elaboration and characterization of La2NiO4+δ powders and thin films via a modified sol–gel process

Polycrystalline thin films of La₂NiO_4+δ have been synthesized on yttria stabilized zirconia (YSZ) substrates by dip-coating using a polymeric sol. Crack-free films were obtained after sintering in air at temperatures ranging from 800°C to 1000°C. The microstructure, characterized by SEM, shows the formation of dense polycrystalline films with smooth surface and mean grains size of 140 nm, for films sintered at 1000°C. A correlation between grains size and non-stoichiometry in powders have been made in our processes. The thickness, evaluated for rugosimetry measurements, is thin (80 nm) and is a function of the viscosity of the sol. The higher the thickness, the higher the viscosity. As the non-stoichiometry level is controlled by the oxygen partial pressure, an evolution of non-stoichiometry in thin film has proposed. Then, it is possible by modifying synthesis and processing parameters to prepare thin films with a controlled microstructure (thickness, porosity and non-stoichiometry).     

Straightforward synthesis of Ti-doped YSZ gels by chemical modification of the precursors alkoxides

Translucent, homogeneous, and monolithic gels of the [(ZrO₂)_0.92(Y₂O₃)_0.08]_1?x(TiO₂)_x system, where x = 0, 0.05, 0.08, and x = 0.10 (mol), have been reliably obtained, for the first time, by a sol–gel route from zirconium (IV) n-propoxide (Zr(OPrⁿ)₄), yttrium acetate hydrate and titanium (IV) isopropoxide (Ti(OPrⁱ)₄). Chemical modification of both alkoxides, zirconium (IV) n-propoxide and titanium (IV) isopropoxide, by acetic acid allows us to change the hydrolysis and condensation behavior of them. Their modification implies the formation of chelating and bridging acetates avoiding the formation of precipitates. The line width and some shoulders in the FT-IR spectra of the solution, resulting of the mixture of the precursors and the catalysts, during the hydrolysis reaction suggest that both coordinations, chelating and bridging, should occur. Furthermore, the separation of the steps of hydrolysis and condensation allows to achieve conditions under which hydrolysis of the molecular precursor is slowed, whereas condensation is promoted under chemical reversibility to ensure a crystalline product at low calcination temperatures. In addition, the formation of metalloxane bondings (M–O–M’, M and M’ = Zr, Y, and Ti) has been confirmed by FT-IR throughout the sol–gel process. At about 630 °C, the crystallization of yttria stabilized zirconia (YSZ) for x = 0 or a titania-doped yttria stabilized zirconia solid solution (Ti-doped YSZ) for x = 0.05, 0.08, and 0.10 is detected by DTA-TG. By SEM-EDX and TEM-EDX the presence of Zr, Y, and Ti elements, in the adequate proportions according to the nominal compositions, has been proven in both dried and calcined gels.     

Oxygen detection using yttria-stabilized zirconia thin films doped with platinum

Yttria stabilized zirconia (YSZ) thin films are obtained using both spray-pyrolysis and dip-coating. The ability of YSZ films incorporated with platinum nanospecies (Pt-YSZ) to detect oxygen is compared with that of pure YSZ thin films using a new experimental setup. With this system, the surface electrical resistance of the films as a function the oxygen content is measured at a fixed temperature. In addition, the effects of thermal annealing on the oxygen sensitivity of the films are observed. Platinum doped samples, Pt-YSZ, show different kinetics of carrier diffusion as compared to pure YSZ samples.     

Coating of oxide powders with alkoxide derived zirconia

Coating of alumina powders with tetragonal zirconia grains in the nanometric size range was obtained from a modified zirconium n-propoxide sol.Powder sedimentation observations and washing experiments were performed to show modifications of particles surface. Amorphous precursor film formation and crystalline zirconia coating were characterized by transmission electron microscopy. Crystallographic relationships between zirconia and alumina particles were also observed.     

Surface changes of yttria‐stabilized zirconia in water and Hanks solution characterized using XPS

Adhesion of soft and hard tissues to yttria‐stabilized zirconia (YSZ) has been reported, despite its chemical inertness. To investigate the underlying mechanism of adhesion of hard and soft tissues to YSZ in dental implants, YSZ disks with (100), (110), and (111) crystalline planes were immersed in water for 60 days and in Hanks solution for 7 days, and the changes in the surface chemical states were characterized using X‐ray photoelectron spectroscopy. After immersion in water for 60 days, the concentration of hydroxyl groups on the YSZ surface increased. Therefore, the surface of YSZ was hydrated during immersion in water. In addition, phosphate groups were formed on the surface of YSZ immersed in Hanks solution. We conclude that the formation of phosphate on the YSZ surface in physiological conditions can promote reaction with the surrounding tissues.