溶胶-凝胶法制备β-锂霞石纳米粉体

采用溶胶-凝胶法合成了β-锂霞石超细粉体,利用差热-热重分析仪、X-射线衍射仪、扫描电子显微镜等对溶胶-凝胶的形成以及样品的物相和形貌进行分析。研究了柠檬酸与金属离子比、溶液的pH值、成胶温度,粉体灼烧温度和时间等对样品物相和形貌的影响。结果表明,当柠檬酸与金属离子比为2：1、pH=3、温度控制在65℃时,得到稳定的溶胶,蒸发干燥后的凝胶在900℃~1300℃温度范围进行煅烧,获得了物相纯度较高的β-锂霞石粉体,粒径约20nm~50nm。     

琼脂糖凝胶中树枝状银的生长研究

以琼脂糖凝胶作为模板、还原剂和稳定剂,通过溶胶-凝胶法制备琼脂糖/纳米银复合凝胶,对所得到的银纳米粒子进行了表征. 在复合凝胶外侧使用铝箔破坏凝胶中银纳米粒子的平衡状态,实现银纳米粒子在凝胶中的聚集并生成三维树枝状结构,并对树枝状银进行了表征. 结果表明,银纳米粒子为球形,粒径在20 nm左右,分散性好. 以琼脂糖凝胶为模板生长的树枝状银形状完整,尺寸与复合凝胶的样品大小有关,可达厘米级. 树枝状银的形貌可通过改变硝酸银浓度进行调控. 树枝状银结构的形成是扩散限制凝聚的结果. 关键词:琼脂糖;银纳米粒子;树枝状银;复合凝胶;可控制备     

Preparation of long alumina fibers by sol-gel method using tartaric acid

Long alumina fibers were prepared by sol-gel method.The spinning sol was obtained by mixing aluminum nitrate,tartaric acid,and polyvinylpyrrolidone with a mass ratio of 10∶3∶1.5.Thermogravimetry-differential scanning calorimetry (TG-DSC),Fourier transform infrared (FT-IR) spectra,X-ray diffraction (XRD),and scanning electron microscopy (SEM) were used to characterize the properties of the gel and ceramic fibers.A little of α-Al2O3 phase is observed in the alumina precursor gel fibers sintered at 1273 K.The ...     

Synthesis of nanosize MnO_2 and its performence

0　INTRODUCTIONNanosizeMnO2 showsmanypositivepropertiesasacatalystandelectrochemicalpowersources .MnO2 isakindofcathodematerialforadrycell,alkaline man ganesebattery ,lithiummanganesebattery .ThepropertiesofMnO2 exertadecisiveeffectonthecells[1～ 3] .NanoparticalsofMnO2 aresosmallthattheycanbedis persedamongelectrolytysisMnO2 toincreaseitssurfaceincontactwithelectrolyte ,AsthespecificsurfaceofNanosizeMnO2 islarge ,itsstructurehasactivemulti centressothatitscurrentdensityandpolarizati…     

碱催化聚酰亚胺/二氧化硅杂化薄膜 的制备与微相结构研究

采用碱催化正硅酸乙酯的溶胶/凝胶工艺制备了一系列透明聚酰亚胺/二氧化硅（PI/SiO2）纳米杂化薄膜。对碱催化条件下的正硅酸乙酯（TEOS）溶胶影响因素进行了分析和讨论,并优选出了稳定溶胶的制备条件：各组分的摩尔比为：n(H2O)∶n(NMP)∶n(TEA)∶n(Si)= 3∶3.75∶0.1∶1,处理温度为50 ℃。对杂化薄膜的微观形貌和结构分别进行了扫描电镜（SEM）和红外光谱（FTIR）分析,结果表明,杂化薄膜都具有很高的光学透明性;随着SiO2含量的增加,杂化薄膜的微观形貌变化不大。SiO2含量增加到30 %(wt)时,SiO2粒子尺寸仍在100 nm左右。通过对其微相结构和形貌的中间演化过程研究发现,SiO2粒子形成于杂化薄膜初期。聚酰胺酸发生酰亚胺化反应的温度也受残留碱的影响而有所降低。     

碱催化聚酰亚胺/二氧化硅杂化薄膜的制备与微相结构研究

采用碱催化正硅酸乙酯的溶胶/凝胶工艺制备了一系列透明聚酰亚胺/二氧化硅（PI/SiO2）纳米杂化薄膜。对碱催化条件下的正硅酸乙酯（TEOS）溶胶影响因素进行了分析和讨论,并优选出了稳定溶胶的制备条件：各组分的摩尔比为：n（H2O）∶n（NMP）∶n（TEA）∶n（Si）=3∶3.75∶0.1∶1,处理温度为50℃。对杂化薄膜的微观形貌和结构分别进行了扫描电镜（SEM）和红外光谱（FTIR）分析,结果表明,杂化薄膜都具有很高的光学透明性;随着SiO2含量的增加,杂化薄膜的微观形貌变化不大。SiO2含量增加到30%（wt）时,SiO2粒子尺寸仍在100 nm左右。通过对其微相结构和形貌的中间演化过程研究发现,SiO2粒子形成于杂化薄膜初期。聚酰胺酸发生酰亚胺化反应的温度也受残留碱的影响而有所降低。     

正交试验法研究定形复合相变材料的制备工艺

为制备适用于调温纺织品领域的定形相变材料,用溶胶-凝胶法制备了复合相变材料,其中定形材料为以正硅酸乙酯为前驱体通过溶胶-凝胶法制得的二氧化硅凝胶,以月桂酸/十六醇二元低共熔物为相变材料.采用正交试验法研究了溶胶-凝胶法制备复合相变材料的工艺条件.各因素影响复合相变材料的控温能力次序为:酯PCM比>酯水比>pH>反应温度...     

Effect of Al_2O_3 on the Process Performance of ZrO_2 Microspheres

Al_2O_3-ZrO_2 microspheres were prepared by internal gelation method.The effects of Al~(3+) on the stability of solution and performance of gel spheres were studied.Al~(3+) had a great influence on the stability of the solutions,and the more of the amount of Al~(3+),the shorter of the stabilization time.Because Al~(3+) did not copolymerize with Zr~(4+) during the sol-gel transformation,the strength of gel sphere added with Al~(3+) was low and deformed easily as it was squeezed.The results of our experiments well verify Glasser team's speculation and conclusions.At the same time,based on the experimental results,we prepared Al_2O_3-ZrO_(2 )composite microspheres with higher content of Al_2O_3 by controlling the pH of the solution.The change curve of viscosity with time and the stabilization time of the solution with different Al~(3+) dosage were given,which could provide references for industrial mass production.Samples without hydrothermal treatment cracked severely,while the samples hydrothermally treated kept structural integrity with no cracks after calcined.Al_2O_3-ZrO_(2 )microspheres with no segregation and phase separation were prepared and alumina evenly distributed in the zirconia matrix.When the content of Al_2O_(3 )was low,the tetragonal phase was stable.And the cubic phase was obtained when the content of Al_2O_3 was more.     

耐高温三乙醇胺毛细管气相色谱柱的制作和测评

三乙醇胺可以被用作固定液来制作气相色谱柱．由于三乙醇胺分子量较低，固定相容易挥发，因而该色谱柱允许使用温度很低．为了提高此类色谱柱的使用温度，用溶胶-凝胶法制作了三乙醇胺的毛细管气相色谱柱．甲基三甲氧基硅烷单体水解后逐渐缩聚成凝胶结构，此凝胶也可与含羟基的三乙醇胺以及石英毛细管内壁上的硅羟基脱水缩合，因此三乙醇胺与毛细管内壁间通过一系列化学键维系着．测试结果表明，用此法制成的色谱柱最高使用温度可以大幅度地提高．     

溶胶凝胶法制备SiO2工艺

以正硅酸乙酯（TEOS）为主要原料，乙醇为溶剂，盐酸或氨水等为催化剂可制得硅酸凝胶．探讨了溶胶凝胶反应的机理及催化剂、水、溶剂及反应温度等对胶凝时间、凝胶的黏度、结构等的影响．采用先酸性后碱性的两步Sol-Gel法可大大缩短胶凝时间．     

两种不同方法制备TSAG纳米粉体的对比研究

采用溶胶-凝胶法和共沉淀法制备TSAG纳米粉体,利用XRD和SEM等测试手段对不同方法合成的TSAG纳米粉体进行表征,并根据谢乐公式计算出粉体粒径大小。结果表明共沉淀法经1200℃煅烧6h可得纯度高,平均晶粒尺寸为49.7nm的TSAG粉体,溶胶-凝胶法经1000℃煅烧3h可得纯度高,平均晶粒尺寸为23.25nm的TSAG粉体。从煅烧温度、保温时间以及制备所得粉体粒径大小对这两种方法进行比较。相较于共沉淀法,采用溶胶-凝胶法可获得晶相更纯,粒径更小,颗粒分布均匀,分散性能好的TSAG粉体,且此方法更省时节能。     

Preparation and densification of BaTiO3 nanopowder by sol—gel autoigniting synthesis

Autoigniting synthesis of gel from Ba(NO3)2,TiO(NO3)2 and C6H8O7.H2O aqueous solution was investigated at an initial temperature of 600℃ and tetragonal BaTiO3 nanopowder with particle size of 80nm was prepared.It is indicated that the specific surface area of the combustion product before and after calcination is 14.74m^2/g and 12.49m^2/g,respectively.The combustion wave is composed of solid phase reaction zone and gaseous phase flame reaction zone.The combustion flame temperature is 1123K derived from thermo couple measurement.The characteristics and densification behavior of the sol-gel autoigniting synthesized BaTiO3 nanopowder were in vestigated.     

Preparation and chromatographic evaluation of thermoresponsive N-isopropylacrylamide copolymers stationary phases containing amino groups

Two cationic thermoresponsive stationary phases were designed and prepared containing poly[N-isopropylacrylamide-co-( 2-dimethylamino) ethylmethacrylate] and poly [N-isopropylacrylamide-co-( 2-diethylamino) ethylmethacrylate]via a simple method,the direct copolymerization of monomers with double bonds on silica surfaces. The two copolymers were synthesized by radical polymerization and then characterized using Fourier transform infrared and gel permeation chromatography. The thermoresponsive property and amounts of copolymers grafted on silica were determined through transmittance measurements and thermogravimetric analysis,respectively. The copolymers grafted silica particles were then applied as high-performance liquid phase ( HPLC) stationary phases for chromatographic separation. Chromatographic properties of mobile phases at different pH values were evaluated by changing temperatures and using benzene and hydrocortisone as the test analytes. Retention time of the analytes was prolonged with increasing temperature on both thermoresponsive columns due to enhanced hydrophobic interaction between analytes and stationary phases. The resolution increased with increasing pH of mobile phase. The optimal separation was obtained at phosphate buffer solution ( 10 mM,pH 8. 0) and at 50 ℃ . The pH of mobile phase had a crucial effect on separation efficiency. The results illustrated that poly[N-isopropylacrylamide-co-( 2-diethylamino) ethylmethacrylate] copolymer modified silica was more advantageous for the temperature-responsive chromatographic separation because its lower critical solution temperature was relatively lower compared to the poly[N-isopropylacrylamide-co-( 2-dimethylamino) ethylmethacrylate] stationary phase.     

Preparation and characterization of silica gel powders

ＰＲＥＰＡＲＡＴＩＯＮＡＮＤＣＨＡＲＡＣＴＥＲＩＺＡＴＩＯＮＯＦＳＩＬＩＣＡＧＥＬＰＯＷＤＥＲＳＬｉＺｈｏｎｇｊｕｎＺｈａｏＱｉｎｓｈｅｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＮｏｎｆｅｒｒｏｕｓＭｅｔａｌｕｒｇｙ,ＣｅｎｔｒａｌＳｏｕｔｈＵｎｉｖｅｒｓｉｔｙ...     

Photocatalytic Degradation of Methyl Thionine Chloride in Aqueous Solution over Nanometer （ CdS/TiO2 ）/MCM-41

（ CdS/ TiO2 ）/ MCM-41 loaded nanometer photocatalyst was prepared by the sol-gel method and dipping process, the photocatalytic degradation of methyl thionine chloride in water was investigated by using the photocatalyst. The experimental results show that the optimum concentration of CdS over TiO2 was 3% （ molar ratio ）, the photocatalytic activity was enhanced when making TiO2 the anatase ptase with a rise of the roasting temperature, and the carrier, mesoporous molecular sieve MCM-41, was beneficial to improving the photocatalytic activity of TiO2 for photocatalytic degradation of methyl thionine chloride. The morphology and the crystalline phase of the photocatalyst were discussed by means of XRD and SEM techniques, and the reaction mechanism of catalytic properties was also discussed.     

Synthesis of spin-ladder Sr<Subscript>14</Subscript>Cu<Subscript>24</Subscript>O<Subscript>41</Subscript> material by citrates sol-gel method

A new process to synthesize polycrystalline samples of Sr14Cu24O41 was presented. Firstly, dry gel powder of Sr14Cu24O41 was synthesized by the citrates sol-gel method, using Sr（NO3）2, Cu（NO3）2, ethylene glycol and citrate acid as raw materials. Then, polycrystalline samples of Sr14Cu24O41 were prepared by solid-state reaction. Thermal Gravimetric and Differential Thermal Analysis（TG-DTA） showed that the temperature for solid-state reaction is at 942 ℃. The samples are identified to be single phase by X-ray Diffraction（XRD） and Scanning Electron Microscopy（SEM）. The SEM pictures showed that the first-step particles were at even size of about 100 nm by this technique. The electronic transport measurements showed that the doping compound were semiconductor with a crossover temperature T in the Arrhenius plot of the resistivity versus temprature.     

溶胶凝胶法制备纳米二茂铁微粒及其电催化性能研究

采用溶胶凝胶法制备了二茂铁微粒后,将所得二茂铁微粒超声分散于甲基三甲氧基硅烷形成的溶胶结构中,得到了溶胶凝胶固载的二茂铁纳米粒子,并制成化学修饰碳糊电极.采用扫描电镜(SEM)方法对制得粉体微粒进行表征,并通过循环伏安实验与计时安培实验测试修饰电极的电催化活性.结果表明:采用溶胶凝胶法分散的二茂铁纳米粒子,粒径约为300nm,将二茂铁固载于SiO2的凝胶结构中有效地提高了修饰电极的稳定性与二茂铁的分散性.在优化的实验条件下,修饰电极对抗坏血酸(AA)的氧化具有明显的催化作用,安培法检测AA的线性范围为3.0×10-6～2.5×10-3 mol/L,检出限为1.0×10-6 mol/L(3sb,n=10).     

固载化杂多酸催化合成乙基叔丁基醚

采用溶胶-凝胶法制备出含杂多酸(HPA)的硅基催化剂,在气相反应条件下,将该催化剂用于叔丁醇和乙醇合成ETBE的醚化反应。重点考察了催化剂的组成、催化剂预处理温度、反应温度、原料摩尔比、空速等因素对醚化反应性能的影响,得到杂多酸质量分数为30%,在450℃下处理后的催化剂为最佳,最佳反应条件:温度为110℃,WHSV为2h-1,n(乙醇)/n(叔丁醇)为1.5∶1。在该条件下考察催化剂的稳定性,结果表明,在72h内活性未发生明显变化,采用烧焦法对催化剂进行再生,重复实验结果说明,采用简单的烧焦再生法,催化剂的活性得到很好的恢复。     

The Mechanism of Sol-Gel Synthesis of Normal Spinel LiMn2O4 with Chelation of Citric Acid

The sol-gel process of citric acid chelating with metal cations for the synthesis of normol spinel LiMn2O4 and the reaction mechanion mechavism were investigated by means of XRD,TG-DTA,and SEM ,the results show that at the beginning lithium citrate and chelate compound of citic acid with manganese ions formed ,and then with heating the esterification and condensation reacions occured between them and glyol ,The products obtained are polymers in which metal cations are distibuted homogeneously on atomic scale that ensur hight reacivity to cations of Li^ and Mn^2 ,Firing the gel grepared by this process ,the lattice diffusions of solid reactant ions caused by non-homogeneity of reactants are elinimated and avoided .At 400℃ phase-pure LiMn2O4 with nanometer scale crystallization having precise stoichiometry and perfect crystallization can be obtained ,The model of chelate coordinated of double -molecule between citric acid and Mn^2 in the gel network is proosed ,It is important for explaining the dispersion state of Mn^2 and the formaiton process of gel by this model.     

绞股蓝总皂苷中单体皂苷的分离纯化

采用硅胶柱层析法分离绞股蓝总皂苷,以氯仿-甲醇混合液为流动相进行梯度洗脱,薄层层析法跟踪检测.5 000 g绞股蓝干草经乙醇提、石油醚脱脂、正丁醇萃取、AB-8大孔吸附树脂脱糖、D-296阴离子交换树脂脱色后得到总皂苷7.87 g.5 g绞股蓝总皂苷进行硅胶柱层析分离,在体积比为9.5:0.5和9:1的氯仿-甲醇洗脱液...