Growth and Characterization of ZnO, SnO2 and ZnO/SnO2 Nanostructures from the Vapor Phase

Zinc oxide (ZnO), tin dioxide (SnO₂) and compounds ZnO/SnO₂ (ZTO) nanostructures have been synthesized successfully from the vapor phase without a catalyst using three different approaches. XRD analyses showed that ZnO with a wurtzite crystal structure, SnO₂ with a rutile crystal structure and zinc stannate (ZnSnO₃) and/or dizinc stannate (Zn₂SnO₄) were condensed from the vapor phase when Zn and/or Sn metal powders or their oxides individually or mixed were used as the starting materials. The formation of either zinc or dizinc stannate was controlled by the Zn/Sn ratio and growth technique. SEM and TEM investigations showed that ZnO grew mainly in the form of wires, rods and belts. These are believed to be originated from the common tetrapod structure of ZnO. While SnO₂ grew in the form of tetragonal rods with rectangle-like cross section and nanoparticles, ZTO grew in the form of nanobelts. The final length, width and thickness were as low as 40, 10 and 5 nm, respectively. The driving forces for growth of nanowires, nanorods, nanobelts, and nanoparticles were found to be vapor density or supersaturation, temperature, pressure and location of deposition from the source materials. The optical absorbance and photoluminescence spectra of all samples showed excitonic character at room temperature implying good crystal quality, and high photocurrent properties suggesting possible applications in nanoscaled functional devices such as optoelectronics and gas sensors.     

Structural/Optical Properties and CO Oxidation Activities of SnO2 Nanostructures

Tetragonal SnO₂ nanostructures with different sizes, band gaps, and defects were synthesized by varying the amounts of ammonia and polyethylene glycol (PEG) used during production and their structural and optical properties were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) crystallography, BET surface area analysis, thermogravimetric analysis, Raman spectroscopy, UV–visible absorption spectroscopy, photoluminescence imaging, and X‐ray photoelectron spectroscopy. In addition, the CO oxidation activity was examined by temperature‐programmed reduction and temperature‐programmed CO oxidation measurements. SEM and XRD analysis revealed that the particle size decreased with increasing PEG, but increased with increasing ammonia. Additionally, the band gaps decreased with increasing ammonia, but not with increasing PEG. Tetragonal SnO formed when larger amounts of ammonia were used, and this was converted to SnO₂ upon annealing at temperatures up to 700°C. The SnO₂ showed a unique strong green emission at 560 nm, which was attributed to a new oxygen deficiency. In addition, a sharp (328 nm) and two broad (390 and 460 nm) photoluminescence peaks corresponding to gap emission and the oxygen vacancies, respectively, were observed. The difference in CO oxidation activity with SnO₂ was attributed to varying sizes and defects formed in response to preparation under different reaction conditions.     

氧化锡对陶瓷色料釉呈色的影响

通过在高温透明釉中添加氧化锡,研究了釉中不同氧化锡含量对各种陶瓷色料呈色的影响,并揭示了陶瓷色料在透明釉和乳浊釉中呈色的显著差异。     

SiC Foams Decorated with SnO2 Nanostructures for Room Temperature Gas Sensing

Cell walls of the commercial silicon carbide (SiC)‐based foams were decorated by one‐dimensional tin dioxide (SnO₂) nanostructures. Thermal evaporation of SnO₂ powder with the assistance of a Au catalyst in inert atmosphere caused the formation of SnO₂ nanobelts on the pore surfaces. The room temperature (RT) ammonia (NH₃) and nitrogen dioxide (NO₂) gas sensing behaviors were investigated systematically in both dry and humid air atmosphere with/without UV activation. The results were compared to those for bare SnO₂ and SiC. It was shown that SiC/SnO₂ composite was efficient to detect low concentration of NH₃ (10–50 ppm) and NO₂ (1–5 ppm) under humid air and UV activation at RT.     

超声波辅助溶胶-凝胶法制备SnO2纳米晶的研究

以SnCl4·5H2O和氨水为主原料,采用超声波辅助溶胶-凝胶法成功合成出了SnO2纳米晶,并讨论了制备过程中超声波作用时间、超声波的有无、烧结温度和表面活性剂等因素对纳米晶性能的影响。样品采用XRD,TEM进行了表征。结果表明,超声波辅助溶胶-凝胶法合成的SnO2微粒呈圆球形,粒径在20 nm左右,其中阴离子表面活性剂-柠檬酸对SnO2纳米晶的团聚能够起到很好的分散作用。     

氟化钙对高温自蔓延合成法制备纳米二氧化锡的影响

为研究CaF2对高温自蔓延合成(SHS)法制备纳米二氧化锡的影响,本文进行了6组关于CaF2添加量与SnO2纳米线产量的平行实验以及1组验证实验,并利用X射线衍射分析及扫描电子显微镜对产物进行表征.实验结果表明:(1) CaF2的添加量与产物的产量之间存在指数关系,且在CaF2添加量为1.5％时,产量实现最大化;(2) CaF2的添加能够提高产物的纯度,并且不改变产物原有的一维纳米形貌.     

沸石基纳米SnO2的制备及性能研究

本文应用水热分散法,通过分散进行分步化学反应,在孔径为0.56nm的沸石分子筛ZSM-5的孔道中成功地组装了纳米SnO2粉体。经过实验:用X射线衍射仪(XRD)对产物的微观结构进行了表征,证明用水热分散法能够有效的把纳米SnO2分散组装在分子筛ZSM-5的孔道中。     

Influence of Li doping on the morphological evolution and optical & electrical properties of SnO2 nanomaterials and SnO2/Li2SnO3 composite nanomaterials

SnO₂ nanomaterials and SnO₂/Li₂SnO₃ composite nanomaterials doped with different Li contents were synthesized via a simple one-step thermal evaporation method. X-ray diffraction patterns showed that with the increase of Li doping, the intensity of Li₂SnO₃ diffraction peaks gradually increased, while that of SnO₂ diffraction peaks gradually decreased. With the increase of Li doping, the width of nanobelts gradually increased, with the morphology changing from banded structure to standard hexagonal sheet structure. The Raman scattering spectra indicated that with the increase of Li doping, the peak of Li₂SnO₃ at 588.8 cm^?1 kept increasing, and the strongest vibration mode A_1g in SnO₂ gradually weakened. X-ray photoelectron spectroscopy revealed that with the increase of Li doping, the surface electrophilic oxygen species in SnO₂/Li₂SnO₃ composite nanomaterials greatly increased. Under the condition of light irradiation with a wavelength of 505 nm, the bright current of the Li-doped SnO₂ samples was higher than the dark current, while that of the SnO₂/Li₂SnO₃ composite nanomaterials was higher than the dark current, which was mainly due to more oxygen vacancies in SnO₂/Li₂SnO₃ composite nanomaterials than electrons excited by light. Consequently, positive photoconductivity gradually weakened, and even the negative photoconductivity emerged.     

乙二醇辅助水热法制备纳米氧化铁的研究

采用乙二醇辅助水热法制备纳米结构的氧化铁,产物通过XRD进行了表征;同时考察了反应时间纳米氧化铁产率的影响。结果表明:制备的最适条件为pH值为11,反应温度90℃,控制反应时间为15 h。     

掺杂La_2O_3对SnO_2电极电学性能的影响

通过共沉淀法制备了掺杂氧化镧的二氧化锡超细粉体,平均粒径为15～20nm,并制得氧化锡电极样品。主要研究了在氧化锡电极中添加不同量的La2O3对电极烧结和电阻率性能的影响。分析电极的电学性能以及微观结构,XRD,SEM等的测试结果表明,适量的La2O3掺杂有利于提高SnO2电极的烧结致密化,同时提高SnO2电极的电学性能。     

多孔竹炭负载SnO2的制备及其电化学性能研究

多孔竹炭为无定形碳,具有丰富的孔结构,孔径分布在1~6 nm之间,且具有较大的孔体积(1.21 cm³/g)。本文以多孔竹炭为载体,采用溶胶-凝胶法制得B₂O₃-SnO₂/C复合材料。SEM和TEM结果显示SnO₂和B₂O₃均匀分布在多孔竹炭表面。多孔竹炭和B₂O₃有效缓冲SnO₂可逆反应的体积变化,提高SnO₂的循环稳定性。将B₂O₃-SnO₂/C复合材料作为负极组装成锂离子半电池,进行电化学性能测试,在1 C(1 C=372 mA/g)倍率下充放电循环200次结束后仍然保留649.9 mAh/g的放电比容量,放电比容量保留率为58.6%。B₂O₃-SnO₂/C复合材料充放电过程受扩散和电容两种行为控制,电容控制的贡献率随着扫描速率的增大而增大。     

Influence of Pd-loading on gas sensing characteristics of SnO2 thick films

Nanocrystalline pristine and 0.5, 1.5 and 3.0 wt% Pd loaded SnO₂ were synthesized by a facile co-precipitation route. These powders were screen-printed on alumina substrates to form thick films to investigate their gas sensing properties. The crystal structure and morphology of different samples were characterized by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy techniques. The 3.0 wt% Pd:SnO₂ showed response of 85% toward 100 ppm of LPG at operating temperature of 250 °C with fast response (8 s) and quick recovery time (24 s). The high response toward LPG on Pd loading can be attributed to lowering of crystallite size (9 nm) as well as the role of Pd particles in exhibiting spill-over mechanism on the SnO₂ surface. Also selectivity of 3.0 wt% Pd:SnO₂ toward LPG was confirmed by measuring its response to other reducing gases like acetone (CH₃COCH₃), ethanol (C₂H₅OH) and ammonia (NH₃) at optimum operating temperature.     

SnO2纳米球的制备、结构及电化学性能研究

以Na2SnO3.4H2O为原料,CO(NH2)2为表面活性剂,采用水热法制备了SnO2纳米球。利用X射线衍射（XRD)、扫描电子显微镜（SEM)、比表面积测试仪（BET）及电化学测试仪等研究材料的结构、形貌、比表面积及电化学性能。结果表明,制备的SnO2材料具有较好的球体形貌,颗粒分散均匀,形状规准,半径约为400 nm,结构呈典型的金红石相。在电压范围为0.01~3 V, 200 mA/g的电流密度下进行充放电测试,首次放电比容量为2206.6 mAh/g,50次循环后,放电比容量保持在440 mAh/g,具有较好的循环性能。     

铜锡改性纳米二氧化钛光催化氧化还原性能的研究

在复合半导体基础上，采用超声浸渍法对催化剂表面作进一步铜改性，制备了铜锡改性的纳米二氧化钛光催化剂CuOx-SnO2／TiO2，考察了表面铜改性、二氧化锡复合对催化剂光催化氧化还原性能的影响．结果表明，表面铜改性和复合都有利于提高催化剂光催化氧化还原能力，二者间表现出相互增强的作用．结合XRD、XPS、TEM等催化剂表征结果，对铜锡改性纳米二氧化钛光激发机制进行了讨论，提出了二氧化碳光催化还原的可能机制．     

热处理温度对Sb:SnO2导电粉结构和性能的影响

SnO2超细粉用作透明导电膜和导电涂料具有广阔的应用前景.以SnCl4·5H2O和SbCl3为原料,采用共沉淀法制得了纳米级的SnO2超细粉.运用差热-失重分析(DSC-TG)、X射线衍射(XRD)、透射电镜(TEM)和紫外光谱分析(UV)等观测手段对微粉末进行了表征,比较系统地研究了热处理温度对粉末颗粒度和电阻的影响规律,探讨了Sb:SnO2导电粉的显色特性.     

SnO_2/In_2O_3纳米材料的制备及其吸附-光催化性能研究

采用水热法制备了一系列不同SnO2/In2O3比例的光催化剂,应用X射线粉末衍射(XRD)和扫描电子显微镜(FESEM)对其微观形貌和晶型进行了分析,通过紫外-可见分光光度计(UV-Vis)评价了复合材料对甲基橙(MO)溶液的吸附性能及催化活性,考察了Sn/In比例值对SnO2/In2O3样品吸附性能及光催化性能的影响。结果表明:当Sn与In摩尔比为2∶1时,对MO的吸附性能和催化性能最好。     

pH值对羧甲基纤维素纳（CMC）粘度性能的影响

研究了捏合法生产羧甲基纤维素（CMC）产品的pH值与产品质量之间影响关系,采用捏合法生产羧甲基纤维素,通过调整碱液添加量,生产出pH值在7．0～11．5之间的产品。在去离子水中、饱和盐水中检验产品的粘度和取代度,产品取代度没有明显变化,去离子水中粘度随pH值增大而降低,饱和盐水中粘度随pH值增大先增大后减小,有一个峰值。分析了不同pH值条件下产品副产物的影响,得出捏合法生产CMC产品pH值的控制范围。     

SnO对SnF2-P2O5-WO3系统玻璃结构和性能的影响

封接玻璃具有耐热好、化学稳定性和机械强度高的优点,被大量运用在真空微电子技术及航天和汽车等众多行业领域。磷酸盐玻璃具有低成本、低特征温度、低稳定性等特点,常被用于封接玻璃的制备。本文采用高温熔融法制备了(60-x)SnF₂-xSnO-35P₂O₅-5WO₃(x=0%,5%,10%,15%,20%,质量分数)组成的玻璃,研究了SnO含量对玻璃结构和性能的影响。通过红外光谱表征了玻璃的微观结构,并测定了玻璃的热膨胀系数和特征温度数值。结果表明,组分中添加SnO可以引入非桥氧来改变O/P原子个数比,从而影响玻璃的结构和性能。随着SnO含量的增加,玻璃的特征温度、封接温度和耐水性能提高,热膨胀系数降低。