用反萃界面沉淀法制备二氧化钛超细粉体

用反萃界面沉淀法,以氨水为反萃剂,通过优化煅烧温度和反萃条件制备出超细TiO2光催化剂.结果表明,采用反萃沉淀法制备超细TiO2光催化剂,改变煅烧温度和水油相加入的方式、降低氨水的浓度、制备温度和陈化时间等因素均有显著的影响.用氨水反萃制备纳米TiO2其最佳煅烧温度为350℃,氨水的浓度和陈化温度存在最佳值.氨水浓度(体积比)为1:5,陈化温度为17.5℃有利于生成小颗粒;陈化时间较短和将水相加入油相有利于生成小颗粒.     

软模板法制备SiO2纳米管

本文报道了以酒石酸为模板剂,正硅酸乙酯（TEOS）为硅源,乙醇为共溶剂,在氨水存在的条件下合成SiO2纳米管的方法和结果。讨论了氨水浓度对SiO2纳米管的形态和生长的影响。实验发现,氨水浓度对SiO2纳米管的形态及生长起着至关重要的作用。在一定的浓度范围内,随着氨水浓度的减小,产物中SiO2纳米管的数量和长径比都增加。并首次讨论了氨水浓度和酒石酸对SiO2纳米管形成过程的作用机理。     

大比表面积超微氧化钇粉末制备的研究

用尿素-氨水调溶液的pH值、均相沉淀的方法制备了大比表面积超微Y2O3粉末,详细地研究了氨水浓度、尿素浓度和尿素-氨水滴加速度对Y2O3粉末比表面积和粒径的影响.在特定条件下,制备了比表面积大于50m2/g,粒径为90nm的超微Y2O3粉末.     

络合剂对化学水浴沉积 ZnS薄膜的影响

采用不同络合剂化学水浴沉积ZnS薄膜,应用台阶仪、SEM、XRD、波谱仪等手段测定了ZnS薄膜的厚度、表面、物相结构及透过率等.结果表明,氨水体系沉积薄膜速度明显慢于另外两种体系,沉积的ZnS薄膜都为立方结构.柠檬酸钠体系沉积的ZnS 薄膜结晶和透过率最佳,但薄膜表面缺陷较多;氨水-联氨体系沉积的ZnS薄膜表面质量最佳,结晶和透过率也较好;氨水体系沉积的ZnS薄膜质量较差.用3种体系沉积的ZnS薄膜用于制备铜铟镓硒Cu(In,Ga)Se2太阳电池,氨水和氨水-联氨体系沉积的ZnS薄膜制备的电池转换效率明显高于柠檬酸钠体系沉积的ZnS制备的太阳电池.     

甘草酸的不同提取方法比较

目的比较水酸法和氨水法提取甘草酸含量的变化。方法利用正交试验4因素3水平选择最佳提取条件（包括加水量、提取次数、煮沸时间、粉碎时间、溶剂量、振荡时间、氨水浓度），用紫外分光光度法在252nm波长处测定甘草酸含量。结果每lOOg甘草粗粉用水酸法提取的最佳条件为：每次加水量2000mL，提取2次，煮沸5min，粉碎20s，氨水法最佳条件为：每次加0．4%氨水2000mL，振荡2h，提取2次。最终氨水法提取率为32％，水酸法提取率为26％。结论在最佳条件下，氨水法提取的甘草酸纯度和提取率明显高于水酸法。     

球形SiO2颗粒的合成及反应机理

利用Stober方法合成了球形SiO2颗粒.在乙醇和水的混合溶剂中,以正硅酸乙酯(TEOS)为硅源、氨水作催化剂,在40℃水浴下制备SiO2球形颗粒.通过改变反应物TEOS以及催化剂氨水的加入量,制备了不同粒径的球形SiO2颗粒.利用扫描电镜(SEM)可以看出,随着TEOS和氨水加入量的增加,SiO2颗粒的粒径增大,并探讨了其变化机理.     

纳米介孔CeO2的合成及表征

采用烷基聚氧乙烯基醚(Brij35)非离子型表面活性剂为模板剂,乙醇水溶液为溶剂合成了高比表面和孔径集中的介孔CeO2,考察了氨水和铈源的添加顺序、pH值等合成条件对介孔CeO2比表面、孔径分布和热稳定性的影响.运用XRD、FT-IR、DTA、N2吸附-脱附和比表面-孔径测定等手段进行了表征.结果表明,氨水加入铈源与模板剂的混合液中有利于形成介孔CeO2,且pH值在9～10范围内所得介孔CeO2材料具有较大的比表面积、孔容和较好的热稳定性.     

氨水槽泄漏原因分析

通过宏观检验、化学成分分析、金相检验等手段对氨水槽泄漏的原因进行了分析。结果表明：在较高焊接应力和氨水的共同作用下产生应力腐蚀是造成氨水槽泄漏的主要原因。     

自清洁氟碳铝单板用N-TiO_2薄膜制备工艺参数优化

以尿素和氨水为氮源,采用溶胶-凝胶法低温制备了具有可见光活性的N-TiO2光催化剂,并用XRD、SEM、FT-IR、UV-Vis等表征手段,研究其晶体结构和光催化性能。结果表明,以尿素为氮源,在pH值=2、n(醇)∶n(钛)为10、水浴温度为65℃、n(氮)∶n(钛)为0.06条件下制备的N-TiO2以锐钛矿为主,结晶度好,薄膜表面均匀平整;与以氨水为氮源制备的N-TiO2比较具有更好的可见光活性。     

沉淀法制备高纯SiO_2粉体

采用分步沉淀法,以自制含硅溶液与氨水反应制备高纯SiO2粉体,分析溶液pH、氨水浓度及酸洗工艺对SiO2粉体纯度的影响。结果表明:除去含硅溶液在pH为7时的沉淀物后,继续与氨水反应的沉淀物经过酸洗,可得到常规金属杂质质量分数仅为1.8×10-6的超高纯纳米SiO2粉体。     

水热法制备二氧化锡纳米微粒及其表征

通过水热法,使五水四氯化锡在氨水的环境中合成纳米级的二氧化锡微粒。采用冷冻干燥法得到粉体。使用XRD对实验合成的产物进行一系列的分析,结果发现所得的二氧化锡粉体基本为四方晶系（即金红石型）。纳米二氧化锡微粒有近球形,棒状,椭球形等的形貌,其粒径范围从4nm到120nm。本实验主要研究以下几个因素对二氧化锡粉体形貌的影响：溶液的浓度、合成温度、合成时间及溶液pH值。     

溶胶-凝胶法制备纳米氧化锡及其性能表征

以SnCl4·5H2O为原料,采用溶胶-凝胶法制备了纳米SnO2粒子,研究了焙烧温度、碱的种类及反应物浓度对纳米SnO2粒子大小和分散状态的影响。采用XRD、TEM、ED等技术对SnO2纳米粒子的性能进行了表征。实验结果表明:用氨水和尿素作为沉淀剂,控制反应结束时pH值为7,在600℃焙烧,制备得到粒子尺寸约为15nm、分散性良好的纳米SnO2粒子。     

Structural and optical characterization of tin dioxide nanoparticles prepared by a surfactant mediated method

In this study tin dioxide nanoparticles were synthesized using a cationic surfactant (cetyl-trimethyl ammonium bromide) as the organic template and the hydrous tin chloride and liquid ammonia as the inorganic precursor. Samples were characterized by X-ray diffraction, transmission electron microscopy and UV–visible absorption, photoluminescence and Raman spectroscopy. The X-ray diffraction pattern of the as prepared sample is indexed to rutile phase of tin dioxide without any trace of an extra phase and particle size 7–8 nm which is further confirmed by electron microscopy. The UV–visible spectrum shows that the absorption edge is blue shifted and the band gap of the prepared sample is 4.0 eV which is larger than the bulk tin dioxide (3.6 eV).     

Synthesis, characterization and photoluminescence studies of ZnOrod@SnO2 nanocomposites

The synthesis of II-VI semiconductor (ZnO_rod@SnO₂) nanocomposite materials with core-shell morphology has been reported. ZnO nanorods were grown by hydrothermal technique using zinc acetate as the reactant. SnO₂ was coated on the nanorods by a simple technique of colloid chemistry. The formation of tin dioxide shell on the ZnO nanorods was confirmed by the TEM images of the resultant materials. The formation of the nanocomposite was also supported by XRD pattern. The effect of tin dioxide shell on the optical properties of ZnO was investigated by photoluminescence spectroscopy and Raman spectroscopy.     

银氧化锡水热体系的共沉积反应协同性研究

研究了水热反应过程中银和二氧化锡共沉积的协同性。分别对水热反应过程中银的还原、二氧化锡的晶化沉积以及银和二氧化锡的共沉积进行了研究,结果表明,水热反应体系中H+或OH-的关联作用使二氧化锡的晶化沉积反应与银的还原反应相适应,并且由于银粉和银氧化锡复合粉体结构形貌上的差异,二者表现出内在的协同性,实现了银和二氧化锡的共沉积。     

CO and NH3 sensor properties and paramagnetic centers of nanocrystalline SnO2 modified by Pd and Ru

Nanocrystalline gas sensitive materials based on tin dioxide modified by Pd or Ru were synthesized via wet chemical route. The interaction of modified materials with CO and ammonia was studied by in situ DC-conductivity measurements and ex situ EPR spectroscopy. Modification by Pd yields the material highly sensitive to CO in low temperature region, while Ru-modified SnO₂ is very sensitive to NH₃ at raised temperature. We have detected that O₂⁻ and OH radicals are the main spin centers in unmodified nanocrystalline tin dioxide. The modification of tin dioxide by Pd and Ru is accompanied by formation of new spin centers in the samples: Pd^+ 3 and Ru^+ 3. The concentration of these paramagnetic species on the materials interacting with CO and ammonia gases decreased because of their transition to the diamagnetic state Pd^+ 2, Pd⁰ and Ru^+ 4, respectively.     

The Effect of Operating Modes on the Response of Ammonia Sensors Based on Tin Dioxide Films

Technical Physics Letters - The influence of operating modes on the response of ammonia sensors based on tin dioxide films has been studied. Samples have been obtained as a result of high-frequency...     

Nanostructure SnO2 and supported Au catalysts: Synthesis,characterization, and catalytic oxidation of CO

Nanostructure tin dioxide (SnO₂) powders prepared by sol-gel dialytic processes using tin (IV) chloride and anhydrous alcohol as start materials, ammonia gas as catalyst of the formation of colloid solution and agent of removing Cl⁻, and by introducing dialytic processes to improve and accelerate the formation of gels. From the result of TG–DTA analyses, the dried samples were calcined at 673 K in air for 3 h. Tin dioxide nanoparticles were characterized by thermogravimetry and differential thermal analyses (TG–DTA), X-ray diffraction (XRD), nitrogen adsorption–desorption, X-ray photoelectron spectroscopy (XPS). The average particle size of the as-prepared tin dioxide was about 5 nm. The as-prepared SnO₂ possessed mesoporous structure and large surface area. The Au/SnO₂ catalysts for low-temperature CO oxidation were prepared by the deposition–precipitation method using as-prepared SnO₂ powders as the support. The Au/SnO₂ catalysts exhibited high catalytic activity for low-temperature CO oxidation. The nanostructure SnO₂ has promising applications in sensor, catalyst, catalytic support, mesoporous membranes, etc.     

制备条件对ATO包覆氧化硅导电粉电性能的影响

采用非均匀成核法制备了ATO包覆氧化硅导电粉体。正交实验的结果表明,各因素对ATO包覆纤维效果的影响从大到小依次是包覆悬过程中氧化硅的用量、包覆层溶液离子浓度、反应过程的pH值、包覆时反应温度及包覆离子溶液加入速度。通过正交实验所确定ATO包覆氧化硅粉体的合理工艺参数:包覆悬过程中氧化硅的用量保持在0.4g/mL、包覆过程的pH值控制为2.0、包覆层离子浓度为0.6mol/L、包覆离子溶液加入速度为0.5mL/min、反应温度为50℃。通过正交实验所确定的合成参数所得的复合导电粉体的电阻率只有108.1Ω.cm。     

Effects of electron beam irradiation on tin dioxide gas sensors

In this paper, the effects of electron beam irradiation on the gas sensing performance of tin dioxide thin films toward H₂ are studied. The tin dioxide thin films were prepared by ultrasonic spray pyrolysis. The results show that the sensitivity increased after electron beam irradiation. The electron beam irradiation effects on tin dioxide thin films were simulated and the mechanism was discussed.