纳米锑掺杂氧化锡的制备及表征

以无机盐SnCl4·5H2O和SbCl3为初始原料,以乙醇作为溶剂,采用溶胶-凝胶法结合超临界流体干燥(supercritical fluid drying,SCFD)技术制备了纳米锑掺杂氧化锡(antimony doped tin oxide.ATO)粉体.通过热重-差示扫描热分析、X射线衍射、扫描电子显微镜、透射电镜,对前驱体粒子以及ATO粒子的结构进行了分析.探讨了热处理温度、前驱体千燥方式对前驱体以及纳米粒子的形貌、粒径、分散性、晶型、结晶度的影响,并讨论了SCFD技术干燥前驱体的机理.结果表明:采用溶胶-凝胶法结合超临界CO2干燥技术,在给定的反应条件下,能够制得疏松的、良好掺杂的四方型结构的纳米ATO粒子,粒径约15～30nm,分散性好.     

应用超临界流体干燥技术制备纳米锑掺杂氧化锡的研究

以无机盐SnCl4·5H2O,SbCl3为起始原料,以乙醇为溶剂,采用溶胶-凝胶法制备纳米锑掺杂氧化锡(ATO)粒子.在洗涤除去醇凝胶中的NH+和Cl-后,尝试将超临界流体干燥(Supercritical Fluid Drying,SCFD)技术应用于醇凝胶的干燥.醇凝胶干粉经过高温烧结后,制得了疏松结构的纳米ATO粉体.采用XRD、TG/DSC、FESEM、TEM等分析方法对制得的前驱体干粉、纳米ATO粒子进行表征.XRD结果表明,采用溶胶.凝胶法结合超临界流体干燥技术制得了疏松的、四方型金红石结构的纳米ATO粉体,纳米ATO晶化程度高,并随着烧结温度的升高而升高.TG/DSC分析显示,600℃时前驱体分解完全,得到约78.2%的ATO粒子.从FESEM及TEM照片可以看出,疏松的纳米ATO粒子轻微地贴在一起,粒子的粒径在25 nm左右.经过对超临界CO2干燥技术(SCFD)消除前驱体粒子团聚的机理进行分析,揭示了采用超临界CO2流体干燥醇凝胶能够使前驱体粒子保持松敝的结构.因此采用溶胶-凝胶法结合超临界流体技术制得疏松的前驱体干粉,对最终获得粒径小、低团聚、分散性好的纳米ATO粉体的至关重要.     

溶胶-凝胶法制备锑掺杂氧化锡纳米粉体

以金属锡粉和三氧化二锑为金属原料,制备得到柠檬酸锡、锑的配合物溶液,向其中加入乙腈,形成溶胶-凝胶过程。对洗涤后的凝胶进行不同温度热处理得到锑掺杂氧化锡纳米粉体。随着锑掺杂量的增加,纳米粉体的晶粒减小,比表面积增加,晶胞参数也发生相应变化。随着热处理温度的升高,纳米颗粒长大,比表面积减小,高锑掺杂量的氧化锡纳米粉体显示出结晶性下降的趋势。     

超临界流体干燥法制备纳米掺锑氧化锡粉体

以SnCl4.5H2O和SbCl3乙醇溶液为原料制备前驱体掺锑氢氧化锡胶体沉淀,采用乙醇超临界流体干燥法干燥前驱体;用TG-DTA、XRD、TEM、BET等方法对粉体的结构、物相、形貌进行表征。结果表明,采用乙醇超临界流体干燥法可得到高比表面积的掺锑氧化锡纳米粉体。     

锑掺杂氧化锡纳米粉体的制备研究

以五水氯化锡和三氯化锑乙醇溶液为原料制备得到前驱体锑掺杂氢氧化锡胶体沉淀,采用乙酸异戊酯共沸干燥法对前驱体进行干燥;用XRD,TEM,IR,BET等方法对粉体的物相、形貌、分散性和比表面积进行表征.结果表明,乙酸异戊酯干燥所得的锑掺杂氢氧化锡微粉经热处理后得到了团聚少、分散性好、晶体颗粒小、粒度均匀的锑掺杂氧化锡纳米粉体.     

溶胶-凝胶-超临界流体干燥法制备纳米3Y-ZrO2

本文以无机盐 ZrOCl ·8H O 和 Y(NO ) 为前驱体,乙酸络合,通过溶胶-凝胶法和超临界流体干燥制 2 2 3 3备 YSZ 纳米晶,并用XR D 、T E M 等手段对其进行表征。结果表明,纳米粒子晶粒细小、均匀,近似球形,颗粒粒径在1 0 n m 左右,没有明显团聚现象。     

溶胶-凝胶法制备RDX/AlOOH

以氯化铝为前驱物,N,N-二甲基甲酰胺为AlCl3.6H2O和RDX的溶剂,1,2-环氧丙烷为胶凝剂,常温常压下,采用溶胶-凝胶法制备RDX/AlOOH复合炸药,产物用超临界流体干燥后得固体粉末。用扫描电镜和DSC研究了复合炸药的形貌分析和热分解特性。测试了复合炸药的撞击感度、摩擦感度。结果表明,溶胶-凝胶法与超临界流体干燥技术相结合,可以较好地保持凝胶的多孔结构;其热分解过程不同于物理掺杂的混合炸药,DSC曲线上熔化吸热峰几近消失,RDX/AlOOH复合炸药的撞击感度和摩擦感度均较低。     

溶胶-凝胶法制备纳米二氧化钛的工艺研究

以钛酸丁酯为主要原料,采用溶胶-凝胶法制备纳米二氧化钛。通过对溶胶-凝胶法中各个主要影响因素的考察,得到制备纳米二氧化钛材料的优化工艺条件为:配制无水乙醇与水的混合液,并调节pH=2～3,缓慢加料;钛醇盐与水的摩尔比为2～4,乙醇与钛醇盐摩尔比为6～8,溶胶体系pH=2～3,水解成胶化温度为25℃～30℃。     

溶胶-凝胶法制备纳米二氧化锆

以锆的无机盐 (ZrOCl2 ·8H2 O)为前体 ,采用溶胶—凝胶法制备 ,常压下流动氮气气氛干燥获得了纳米二氧化锆。采用MicromeriticsASAP - 2 0 2 0C型吸附仪、XRD和TEM对其进行了表征。结果表明该方法制备的纳米二氧化锆具有粒径小、比表面大和热稳定性好的特点     

纳米掺锑氧化锡粉末的制备及表征

以 SnCl4·5H2O和SbCl3乙醇溶液为原料,采用离子交换除氯水解法得到无氯离子的掺锑氢氧化锡胶体沉淀,以正丁醇作脱水剂对胶体进行共沸干燥处理,所得的掺锑氢氧化锡干微粉经热处理后得到了四方形金红石结构的掺锑氧化锡纳米粉末.用TG-DTA、IR、BET、BJH、XRD、TEM等方法对粉体的结构、物相、形貌进行了表征.     

纳米锑掺杂氧化锡的表面改性研究

以乙醇与水的混合溶液作为改性介质,将纳米锑掺杂氧化锡(Antimony Doped Tin Oxide,ATO)分散于介质中,利用硅烷偶联剂KH-570与纳米ATO表面羟基的脱水反应以及硅烷偶联剂间的缩合反应,制得了KH-570包覆的纳米ATO粉体。通过FTIR、XPS、TG、TEM以及亲油性的测试对纳米ATO粉体的表面结构以及性能进行了表征,探讨了纳米ATO的与硅烷偶联剂的表面接枝情况以及硅烷偶联剂与纳米ATO在弱极性条件下的反应机理。研究结果表明：在ATO纳米粒子表面接枝上了一层约7.36-7.73wt%的KH570,改性后的纳米ATO粒子的亲油性能以及分散性得到大幅度的提高,改性ATO在正丁醇能够稳定分散100h以上。其根本原因在于改性后纳米ATO表面形成了一个网络结构硅烷偶联剂的包覆层,赋予纳米ATO粒子的表面良好的亲油性能以及分散性能。     

Electromagnetic loss mechanisms in antimony doped tin oxide and reduced graphene oxide multilayer films

In this paper, the antimony doped tin oxide (ATO) and reduced graphene oxide (rGO) were prepared by coprecipitation method and modified Hummers’ method, respectively. Both were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and vector network analyzer (VNA). The as-prepared rGO showed typical sheets-like structure and the as-prepared ATO showed typical nano-particle shape. Then, the ATO and rGO multilayer films were designed and the microwave absorption performances were numerically evaluated using finite element methods. The results showed that synergetic effects of interfacial polarization resonance and 1/4λ elimination were stimulated in 10-layerd 1.8 mm multilayer films to give a minimal reflection loss of −45.2 dB @ 16.1 GHz, and −10 dB bandwidth of 5.4 GHz, which was enhanced more than −30 dB in ATO or rGO monophase absorbers with the same thickness. This work provides a novel technical route to realize high-performance microwave absorbers in terms of simultaneously stronger absorption, broader absorption bandwidth and smaller thickness to facilitate higher flexibility and stability for practical applications.     

溶胶-凝胶法制备纳米二氧化铈的工艺研究

采用以柠檬酸为配体的溶胶-凝胶法制备了二氧化铈超细粉末,考察了制备条件:金属离子与配体的物质的量比、反应温度、凝胶烘干温度、焙烧温度及时间对成品粒子的影响.获得了最佳的制备条件:金属离子与配体的物质的量比为1:3、反应温度为65℃、凝胶烘干温度为120℃,500℃焙烧2h.在该条件下制得的二氧化铈纳米粒子平均粒径为7nm,比表面积为115m2/g.     

Catalytic properties of ultrafine molybdenum-cerium oxide particles prepared by the sol-gel method

The structure and catalytic properties of ultrafine Mo-Ce oxide particles prepared by the sol-gel method have been studied by using X-ray diffraction, transmission electron microscopy, temperature-programmed reduction, laser Raman spectroscopy and microreactor tests. It has been shown that for selective oxidation of toluene to benzaldehyde the ultrafine Mo-Ce oxide particles exhibit higher catalytic activity than the larger oxide particles prepared by a conventional coprecipitation method. The unique catalytic properties of ultrafine Mo-Ce oxide particles may be correlated not only to the interaction between molybdenum oxide and cerium oxide, but also to the higher reactivity of lattice oxygen species in the ultrafine oxide matrix. This revised version was published online in July 2006 with corrections to the Cover Date.     

Low-temperature conducting performance of transparent indium tin oxide/antimony tin oxide electrodes

We fabricated transparent indium tin oxide (ITO)/antimony tin oxide (ATO) electrodes using a combined process of spin-coating of hybrid ITO nanoinks, electrospraying of ATO, and hydrogen (H₂) activation carried out at a low annealing temperature of 200 °C. The produced ITO electrode exhibited an enhanced surface densification and phase conversion of In(OH)₃ to ITO. As a result, the H₂-activated ITO/ATO electrodes exhibited excellent transparent conducting performances with a superior sheet resistance of ~47.5 Ω/□ and a good transmittance of ~85.3% as compared to the ITO and ITO/ATO electrodes. Despite the use of the low annealing temperature, the achieved improvement in the conducting performance could be attributed to the synergistic effect of the enhanced carrier concentration and the Hall mobility related to the improved surface densification achieved with the electrosprayed ATO thin film and reduction of the residual In(OH)₃ phase by H₂ activation. Therefore, our method can be used as a novel strategy for obtaining high-performance solution-processed transparent conducting oxides at a low annealing temperature of 200 °C for use in various optoelectronic applications.     

Characterization of indium tin oxide (ITO) thin films prepared by a sol-gel spin coating process

Indium tin oxide (ITO) thin films were prepared by a sol-gel spin coating method, fired, and then annealed in the temperature range of 450-600°. The XRD patterns of the thin films indicated the main peak of the (2 2 2) plane and showed a higher degree of crystallinity with an increase in the annealing temperature. Upon annealing the films at 500 and 600°, two binding energy levels of Sn⁴⁺ ion of 486.9 eV and 486.6 eV, respectively, were measured in the XPS spectra. The ITO film that was annealed at 600° contained two oxidation states of Sn, Sn²⁺ and Sn⁴⁺, and it had a higher sheet resistance based on a rather low doping concentration of Sn⁴⁺. The film that was annealed at 500° and subsequently treated with 0.1 N HCl solution for 40 s showed a sheet resistance of 225 Ω/square. The surface treatment by the acidic solution diminished the RMS (root mean square) roughness value and the residual carbon content (XPS peak intensity of carbon) of the ITO films. It seems that the acid-cleaning of the ITO thin films led to a decrease of the surface roughness and sheet resistance.     

Theoretical prediction of transport coefficients of antimony doped tin dioxide

Doped Tin (IV) Oxide has excellent potential in high-temperature thermoelectrics because of its large bandgap. It has been thoroughly experimentally studied for high-temperature thermoelectric application. Low electron mobility limits the thermoelectric performance of oxides. Understanding the temperature dependence of mobility help increase thermoelectric performance. This is rarely performed. In this work, we study antimony doped tin dioxide. Combining the calculated transport properties and the existing experimental results, we obtain other transport properties. Unlike in bulk materials, the grain boundary scattering competes against the acoustic phonon scattering. The grain size, temperature, and carrier concentration determine the mobility. The small grain, low carrier concentration, and high temperature are beneficial to the mobility. Antimony doping also causes the Fermi level into the conduction band as deep as 0.59 eV, making the large bandgap SnO₂ metallic. Furthermore, the conductivity effective mass demonstrates the doping effect. These findings might help design new oxide thermoelectric materials by decrease the grain size.     

Band gap engineering and low temperature transport phenomenon in highly conducting antimony doped tin oxide thin films

A huge band gap tuning and low temperature transport phenomenon in highly transparent antimony doped tin oxide thin film (Sb:SnO₂) under the influence of swift heavy ions irradiation (SHII) is reported. Structural analysis shows an enhancement in crystallinity at initial fluence of irradiation followed by amorphization at higher fluences. Films were also well studied for their surface morphology by atomic force microscopy and scanning electron microscopy. Band gap analysis reveals a drastic band gap narrowing around 1.1 eV upon SHI irradiation. Transport measurements show that the high conductivity and the carrier concentration decrease upon increase in the fluence of irradiation. The mechanism of charge carrier transport investigated at low temperature is attributed to nearest neighbor hopping (NNH) and variable range hopping (VRH) in different temperature regimes. Origin of the band gap tuning is understood in framework of Burstein–Moss (BM) shift, Quantum Confinement (QC) effect and band-tailing states in amorphous semiconductors.     

Highly conducting and transparent antimony doped tin oxide thin films: the role of sputtering power density

Sb doped SnO₂ thin films were deposited on quartz substrates by magnetron sputtering at 600 °C and the effects of sputtering power density on the preferential orientation, structural, surface morphological, optical and electrical properties had been studied. The XRD analyses confirm the formation of cassiterite tetragonal structure and the presence of preferential orientation in (2 1 1) direction for tin oxygen thin films. The dislocation density analyses reveal that the generated defects can be suppressed by the appropriate sputtering power density in the SnO₂ lattice. The studies of surface morphologies show that grain sizes and surface roughness are remarkably affected by the sputtering power density. The resistivity of Sb doped SnO₂ thin films gradually decreases as increasing the sputtering power density, reaches a minimum value of 8.23×10⁻⁴ Ω cm at 7.65/cm² and starts increasing thereafter. The possible mechanisms for the change in resistivity are proposed. The average transmittances are more than 83% in the visible region (380–780 nm) for all the thin films, the optical band gaps are above 4.1 eV. And the mechanisms of the variation of optical properties at different sputtering power densities are addressed.     

纳米锑掺杂氧化锡制备中超临界CO_2干燥的工艺优化及动力学

纳米锑掺杂氧化锡(ATO)具有优越的光电性能,在制备过程中前驱体干燥处理至关重要。为掌握ATO前驱体的超临界CO2干燥工艺特性,研究了超临界干燥的时间、温度、压力和CO2流量等工艺参数对纳米ATO粒径、比表面积等的影响,进一步探讨了超临界CO2流量对干燥动力学的影响规律,并拟合了干燥曲线方程。结果表明:温度35~40℃、压力10~14 MPa、CO2流量1.2~1.8 L·h-1、干燥5~6 h,最终能够获得平均粒径20~30 nm、高比表面积的纳米ATO材料;流量对干燥速率有明显影响,醇分比0.4为干燥速率由恒速转为降速的临界点,醇凝胶干燥动力学方程能够很好地描述ATO醇凝胶干燥工艺过程。研究结果可为湿法制备纳米材料的湿凝胶干燥工业化生产和控制提供参考。