Hydrothermal synthesis of nano-silicon from a silica sol and its use in lithium ion batteries
Jianwen Liang, Xiaona Li, Yongchun Zhu (?), Cong Guo, and Yitai Qian (?)
Hefei National Laboratory for Physical Science at Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
Received: 11 September 2014 Revised: 31 October 2014 Accepted: 3 November 2014
? Tsinghua University Press and Springer-Verlag Berlin Heidelberg 2014
KEYWORDS silicon,
hydrothermal synthesis, nanomaterials,
silicon sol,
energy storage ABSTRACT
There have been few reports concerning the hydrothermal synthesis of silicon anode materials. In this manuscript, starting from the very cheap silica sol, we hydrothermally prepared porous silicon nanospheres in an autoclave at 180 °C.
As anode materials for lithium-ion batteries (LIBs), the as-prepared nano-silicon anode without any carbon coating delivers a high reversible specific capacity of 2,650 mAh·g–1 at 0.36 A·g–1 and a significant cycling stability of about 950 mAh·g–1 at 3.6 A·g–1 during 500 cycles.
1Introduction
Silicon has been considered as a promising anode candidate material for advanced lithium-ion batteries (LIBs) due to its high theoretical capacity (3,579 mAh·g–1) and relatively low discharge potential (<0.5 V versus Li/Li+) [1]. However, Si exhibits serious volume changes (>270%) during lithiation–delithiation, which leads to a rapid reduction in capacity [2, 3]. Similar to other
electrode materials, using Si materials with a nano-structure is one of means to relieve this problem [4–9].
Various methods have been developed to produce nano-silicon anode materials in order to improve LIBs performance. One of these methods is chemical vapour deposition (CVD) of silanes, by which silicon nanotubes were prepared. After subsequent SiO2 surface-coating, the Si/SiO2 nanotubes were shown to have long cycle life (6,000 cycles with 88% capacity retention), high specific charge capacity (~2,971/1,780 mAh·g–1 at 0.4 A·g–1, and ~940/600 mAh·g–1 at 24 A·g–1) [10]. Nano-silicon anode materials are also prepared by the typical magnesiothermic reduction reaction [11–16]. For example, magnesiothermic reduction of SiO2 at 650 °C was used to synthesize Si nanotubes, which showed a capacity of about 1,900 mAh·g–1 at 0.4 A·g–1, with a reten-tion of ~50% after 90 cycles after carbon coating [11].
Nano Research 2015, 8(5): 1497–1504
DOI 10.1007/s12274-014-0633-6
Address correspondence to Yitai Qian, ytqian@https://www.doczj.com/doc/749631988.html,; Yongchun Zhu, ychzhu@https://www.doczj.com/doc/749631988.html,
With regard to wet chemical synthesis of nano-silicon anode materials, much attention has been paid to the preparation in organic solvents [17–19]. For example, nest-like silicon nanospheres were prepared via reaction of sodium silicide and NH 4Br in a mixed solvent of pyridine and dimethoxyethane in an autoclave at 80 °C for 24 h, and exhibited a reversible specific capacity of 1,095 mAh ·g –1 at 2 A·g –1 after 50 cycles. Si nanoparticles were produced by reduction of SiCl 4 with naphthalene sodium in anhydrous tetrahydrofuran at 380 °C in a Hastelloy Parr reactor, and showed a specific charge capacity of 3,535 mAh ·g –1 at 0.9 A·g –1 and retention as high as 96% after 40 cycles after carbon coating [17]. Si nanoparticles were synthesized via reduction of anhydrous SiCl 4 with sodium–potassium alloy (NaK) in toluene solution under reflux for 4 h, followed by oxidation; the resulting sample of Si/SiO x /SiO 2 showed an initial charge capacity of 610 mAh·g –1 at 0.2 A·g –1 and good cycling stability (maintained at ~600 mAh ·g –1 after 350 cycles) [20]. Recently, an aqueous synthesis of hydrophilic silicon nanoparticles (~2.2 nm) based on the reaction of (3-aminopropyl)trimethoxysilane (C 6H 17NO 3Si) and trisodium citrate dihydrate under
microwave irradiation at 140
°C was reported [21]. Silicon nanowires have also been grown in an aqueous solution [22]. Previously, we have fabricated silicon micromaterials by reducing crystalline Na 2SiO 3·9H 2O with Mg in an autoclave at 200 °C [23]. After being combined with graphene, the as-prepared anode showed a reversible capacity of ~600 mAh ·g –1 at a current density of 3.6 A·g –1 after 360 cycles.
In this study, we hydrothermally prepared porous silicon nanospheres by reducing silica sol with metallic magnesium in an autoclave at 180 °C. Moreover, besides silica sol, this hydrothermal reduction reaction can be extended to the reduction of solid silica powders such as silica aerogel and silicic acid (hydrated silica). The as-prepared nano-silicon anode delivers a high reversible specific capacity of 2,650 mAh ·g –1 at 0.36 A·g –1 and cycling stability about 950 mAh ·g –1 at 3.6 A·g –1 after 500 cycles.
2 Experimental
2.1 Materials
30% alkaline silica sol (industrial, pH = 13) was
purchased from Guangzhou Sui Ze Environmental Protection Technology Co., Ltd (China, http:// https://www.doczj.com/doc/749631988.html,/company/shop1383670764546/ index.aspx). Mg (99%, 100–200 mesh powder), HCl (37%) and hydrofluoric acid (≥ 40%) were purchased from Sinopharm Chemical Reagent Co., Ltd (China). 2.2 Hydrothermal synthesis of nano-silicon The porous silicon nanospheres were prepared by reduction of industrial silica sol with magnesium using a hydrothermal reduction reaction in a stainless autoclave. Silica sol (2.2 g) and Mg (1.5 g) powder were mixed and added into a 20 mL stainless autoclave which was then sealed. Subsequently, the autoclave was maintained at 180 °C for 10 h and then cooled to room temperature. Here, the temperature as 180 °C is the lowest temperature in such reaction of silica sol and Mg. The samples were immersed in hydrochloric acid (1 mol·L –1) for several hours to remove MgO. The resulting solution was washed with distilled water and centrifuged (5,000 rpm, 5 min) to collect silicon. The obtained silicon was dissolved in 10 wt.% dilute HF solution for 10 min to remove unreacted silica and other impurities formed during reduction. The brown-black precipitate was collected by centrifugation, washed with deionized water and ethanol and dried for overnight at 60 °C in a vacuum oven to evaporate residual solvent. We also tested the synthesis of silicon materials by using other kinds of silicon precursors such as silica aerogel and silicic acid (hydrated silica). Experimental details are shown in the Electronic Supplementary Material (ESM). 2.3 Materials characterization
The morphologies of the reaction products were characterized by scanning electron microscopy (SEM, JEOL-JSM-6700F), transmission electron microscopy (TEM, Hitachi H7650 and HRTEM, JEOL 2010). X-ray diffraction (XRD) was performed on a Philips X’ Pert Super diffractometer with Cu K α radiation (λ = 1.54178 ?). The Brunauer–Emmett–Teller (BET) surface area and Barrett–Joyner–Halenda (BJH) pore distri-bution plots were measured on a Micromeritics ASAP 2020 accelerated surface area and porosimetry system. Before analysis, the samples were allowed to dry
under vacuum and degas at 300 °C for 0.5 h under
vacuum (10–5 bar).
2.4 Electrochemical measurements The electrochemical properties of nano-silicon electrodes
were measured with coin-type half cells (2016 R-type)
which were assembled in an argon-filled glove box (H 2O, O 2 < 1 ppm). The working electrode was prepared
by mixing the nano-silicon material, super P carbon
black and sodium alginate (SA) binder in a weight ratio of 60:20:20 in water as solvent. The slurry was
pasted onto a Cu foil and then dried in a vacuum oven
at 80 °C for 12 h. The active material density of each
cell was determined to be 0.5–1.0 mg·cm –2. Metallic Li
sheet was used as the counter electrode, and 1 M LiPF 6
in a mixture of ethylene carbonate/dimethylcarbonate
(EC/DMC; 1:1 by volume) and 10 wt.% fluoroethylene
carbonate (FEC) was used as the electrolyte (Zhuhai
Smoothway Electronic Materials Co., Ltd. (China)). Galvanostatic measurements were made using a LAND-CT2001A instrument at room temperature that
was cycled between 0.005 V and 1.50 V versus Li +/Li
at a rate of 0.36–18 A·g –1.
3 Results and discussion
Silica sol was converted into H 2/Si by the hydrothermal
reduction process with Mg in a stainless steel autoclave.
X-ray powder diffraction (XRD) analysis (Fig. S1, in the ESM) confirmed the main components to be MgO
and Si. Trace amounts of Mg(OH)2 and Mg 2SiO 4 were
also detected in the XRD pattern. The composite reacted specimens were then immersed in a 1 M HCl solution for several hours to remove MgO and
Mg(OH)2 (Fig. S2, in the ESM) and further treated
with HF solution to remove unreacted silica and other impurities formed during reduction.
The XRD pattern of the resulting silicon-based
product is shown in Fig. 1(a). All the peaks can be indexed to the standard pattern of cubic silicon (JPCDS 27-1402) with calculated lattice constants of a = 5.408 ?,
which is close to the reported value of 5.430 ?. The yield of this Si material is above 25%. Moreover, the 2p Si XPS (X-ray photoelectron spectroscopy) spectrum
of the as-prepared sample (Fig. 1(b)) shows—in addition to the strong peak of silicon at 99 eV—a weak peak at 103.5 eV , indicating the existence of small amount of amorphous SiO 2 [24]. Figure 2 shows the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the as-prepared nano-silicon. From the SEM image (Fig. 2(a)), one can see that the as-prepared silicon is composed of uniform sphere-like nano-particles with average diameter of 80 nm. The TEM
image in Fig. 2(b) shows the presence of pores in the spherical nanostructures, which is further confirmed by the enlarged TEM image of Fig. 2(c). It is obvious that the primary pores with a size of several nano-meters are homogeneously distributed. A HRTEM
image (Fig. 2(d)) taken on the edge of an individual nanosphere shows that the porous nanospheres are composed of many nanocrystallites and the pore size is 2–5
nm. The interplanar spacing is about 3.1 ?, corresponding to the (111) planes of the crystalline Si. Nitrogen adsorption measurements (Fig. S3, in the ESM) indicated that the specific surface area of nano- silicon was about 11 m 2·g –1. BJH analyses (Fig. S4, in
the ESM) of the nitrogen desorption curves indicated
Figure 1 (a) XRD pattern and (b) XPS spectrum of the porous Si nanospheres after hydrothermal reduction silica sol process.
Figure 2 The morphology, size, and structure of the resulting porous Si nanospheres. (a) SEM and (b) and (c) TEM image of the spherical porous silicon; (d) HRTEM image taken on the edge of an individual nanosphere.
that the porous Si nanosphere possessed a large amount of nanopores (~4 nm and ~10 nm) and a small amount of macropores.
Moreover, we also synthesized silicon materials by using other kinds of silicon precursor, such as silica aerogel and silicic acid (hydrated silica). Experimental details are shown in the ESM (Extension experiments 1 and 2). XRD, SEM and TEM analysis (Figs. S5–S8) clearly reveals that the crystalline phase of nano-silicon can be hydrothermally synthesized by using other kinds of silicon precursor at relatively low temperature (~200 °C).
In contrast to previous reports, hydrothermal reduction of the silica sol proceeds through the formation of active H intermediates. First, the reaction of H 2O and Mg according to the equation H 2O + Mg = MgO + H 2 (ΔH θ = –316 kJ· mol –1) produces a large amount of heat in a short time which promotes the subsequent reaction leading to the production of silicon. On the other hand, based on the standard electrode potentials E θ(H/H 2O) = –0.93 V , E θ(Mg/Mg 2+) = –2.36 V and E θ(Si/SiO 2) = –0.86 V, reactions such as (1) Mg + H 2O = MgO + 2H, (2) H + SiO 2 = Si + H 2O and (3) Mg + SiO 2 = MgO + Si are thermodynamically spontaneous. It is proposed that the generation of active H intermediates will promote the reaction, which is similar to the Clemmensen reaction in traditional organic synthesis [25]. In the Clemmensen reaction, active H intermediates generated from Zn and HCl
transform carbonyl groups into methylene groups. Moreover, such a hydrothermal reduction of silica sol can be carried out at even lower temperatures than 180 °C through activating the formation of active H intermediates by adding acid, which provides direct proof that the formation of active H intermediates should facilitate the formation of silicon. An extension experiment involving adjusting the pH of the reaction system is given in the ESM (Extension experiment 3 and Fig. S9).
The electrochemical performance of the spherical porous Si nanostructures as an anode was investigated in CR2016 coin cells with lithium foil as a counter electrode. Figure 3(a) shows typical voltage curves during the first five cycles in the voltage window of 0.005–1.50 V versus Li/Li + at a current density of 0.36 A·g –1. In the first discharge curve, a discharge plateau at around 0.8 V can be assigned to the for-mation of a solid electrolyte interface (SEI) layer, which disappears in the following cycle and is related to an initial irreversible capacity loss [12, 26, 27]. The discharge plateau located at around 0.2 V is related to the alloy formation process between Li and crystal Si [28, 29]. Subsequent discharge and charge cycles curves had the voltage profiles characteristic of amorphous Si [30, 31].
The porous silicon nanospheres anode delivers initial discharge and charge capacities of 4,055 and 3,015 mAh·g –1 at 0.36 A·g –1, respectively , corresponding to a first cycle coulombic efficiency (CE) of 74%. The irreversible capacity loss can be mainly attributed to the formation of the SEI layer on the electrode surface and presumably arises partly from electrolyte decomposition, partly from electrically disconnected particles due to the large volume changes [10], and perhaps also from Li atoms “trapped” in the electri-cally connected particles [32, 33]. Meanwhile, after cycling up to 40 cycles at 0.36 A·g –1, the porous silicon nanospheres anode retained a charge capacity of 2,650 mAh·g –1 (Fig. 3(b)), corresponding to about 89% of its initial charge capacity (3,015 mAh·g –1). Further-more, the coulombic efficiency remains near 100% after the first cycle, which means that the porous silicon nanospheres structure can enhance the coulombic efficiency of the electrode due to the increased number of active sites for reversible electrochemical Li storage
[14]. A capacity of 950 mAh·g –1 after 500 cycles at a higher current density of 3.6 A·g –1 and good capacity retention were also attained, with the first three cycles activated at 0.72 A·g –1 (Fig. 3(e)). Some oscillations in the specific capacity values over several cycle periods could sometimes be observed (Fig. 3(e)), although neither the average value of the specific capacities, nor the ability for long cycling were affected. Such oscillations have sometime been observed in previous reports for not only Si anodes [34–36] but also for other kinds of electrode materials [37, 38]. The slight capacity oscillations might result from the temperature difference (between the inside of the cell and the
measurement environment—see Figs. S10 and S11 (in
Figure 3 Electrochemical performances of spherical porous silicon anode. (a) Typical galvanastatic discharge–charge curves of the cell
with spherical porous silicon in the potential region of 0.005–1.5 V versus Li +/Li at a current density of 0.36 A·g –1. (b) Cycling property and coulombic efficiency of the cell with spherical porous silicon at the constant current density of 0.36 A·g –1. ■ as discharge capacity (Q d ), ● as charge capacity (Q c ) and ◆ as coulombic efficiency (Q c /Q d ). (c) The typical galvanastatic discharge–charge curves of spherical porous silicon at different current densities, and (d) the rate performance of a spherical porous silicon anode. (e) Cycling property at 3.6 A·g –1 for 500 cycles.
the ESM) for temperature difference measurements), the surface conditions, the active sites of the sample and the SEI layer thickness [39]. The rate capability of the spherical porous Si anode was evaluated using galvanostatic charge–discharge measurements by increasing the current density from
a low value of 0.36 A·g –1 to a high value of 18 A·g –1 and then back to 1.8 A·g –1 and 0.72 A·g –1 (shown in Figs. 3(c) and 3(d)). The discharge specific capacities were ~2,900, 2,600, 2,000, 1,500, 800 and 350 mAh·g –1 and the coulombic efficiencies were almost 100% at current densities of 0.36, 0.72, 1.8, 3.6, 7.2, and 18 A·g –1, respectively. It is worthwhile to note that the specific capacity reversibly recovers to approximately 1,800 mAh·g –1 once the current density goes back to 1.8 A·g –1 and then go back to about 2,450 mAh·g –1
when the current density back to 0.72 A·g –1. The specific capacity is almost recovered, indicating an excellent rate performance of the silicon anode. The high electrochemical performance of the silicon may be
attributed to its porous nanostructure [12, 40, 41] as
well as the presence of amorphous SiO 2 [10, 42, 43].
The porous nanostructure offers a pathway for the
efficient access of electrons and electrolytes, increased
number of active sites and enhances the contact surface
between the electrode material and electrolyte. Fur-thermore, the presence of pores and amorphous SiO 2
may effectively accommodate the volume changes of
silicon and allow for facile strain relaxation without large mechanical stress during cycling. This should provide a new avenue for large-scale production of anode materials with high electrochemical performance. 4 Conclusions
Porous Si nanospheres have been hydrothermally synthesized based on the reduction of silica sol by magnesium metal in an autoclave at 180 °C. Moreover, besides silica sol, this hydrothermal process can be extended to the reduction of solid silica powders such as silica aerogel and silicic acid (hydrated silica). The porous Si nanospheres without any carbon coating exhibit excellent lithium-storage capacity, high-rate capability and long cycling performance, which may be attributed to the porous nanostructure as well as
the presence of amorphous SiO 2. Since the reactant is cheap, and the reaction conditions are relatively mild, this study should provide a new avenue for the large- scale production of silicon anode materials. Acknowledgements
This work was supported by the 973 Project of China (No. 2011CB935901), and the National Natural Science Fund of China (Nos. 91022033, 21201158). Electronic Supplementary Material: Supplementary material is available in the online version of this article at https://www.doczj.com/doc/749631988.html,/10.1007/s12274-014-0633-6. References
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收稿日期:2008209211 3基金项目:韩山师范学院青年科研基金资助项目(0503) 作者简介:陈城钊(1975— ),男,广东潮州人,讲师,硕士.第2卷 第4期 材 料 研 究 与 应 用 Vo1.2,No.42008年12月 MA TERIAL S RESEARCH AND APPL ICA TION Dec .2008 文章编号:167329981(2008)0420450205 优质纳米晶硅薄膜的低温制备技术及其 在太阳能电池中的应用进展3 陈城钊1,邱胜桦1,刘翠青1,吴燕丹1,李 平1,余楚迎2,林璇英1,2 (1.韩山师范学院物理与电子工程系,广东潮州 521041;2.汕头大学物理系,广东汕头 515063) 摘 要:纳米晶硅薄膜是集晶体硅材料和氢化非晶硅薄膜优点于一体,可望广泛应用于薄膜太阳能电池、光存储器、发光二极管和薄膜晶体管等光电器件的一种新型功能材料.本文综述低温制备优质纳米晶硅薄膜技术的研究进展及其在薄膜硅太阳能电池上的应用.关键词:纳米晶硅薄膜;太阳能电池;低温制备;进展中图分类号:TM914.4 文献标识码:A 纳米晶硅(nc 2Si ζH )薄膜就是硅的纳米晶粒镶嵌在a 2Si ζH 网络里的一种硅纳米结构.由于它具 有较高的电导率(10-3～10-1Ω-1?cm -1)、宽带隙、高光敏性、高光吸收系数等优良的光电特性而引起学术界的重视.纳米晶硅薄膜同时具备宽带隙和高电导这两种太阳能电池窗口材料所需的优良性质,现已成为研究探索的热门纳米薄膜材料 [1] .除用于 制备薄膜太阳能电池外,在发光二极管、光存储器、隧穿二极管、薄膜晶体管以及单电子晶体管等光电器件方面也有潜在应用 [2] . 1 低温制备纳米晶硅薄膜的技术 为了制备适用于以玻璃为衬底的太阳能电池的 纳米晶硅薄膜,近年来发展了低温(<450℃)制膜技术.按成膜过程可分为两大类:一类是先制备非晶态材料,再固相晶化为纳米晶硅;另一类是直接在玻璃衬底上沉积纳米晶硅薄膜[2] . 1.1 固相晶化法 固相晶化(SPC )法的特点是非晶固体发生晶化的温度低于其熔融后结晶的温度.低造价太阳能电 池的纳米晶薄膜,一般以廉价的玻璃作衬底,以硅烷气为原材料,用PECVD 法沉积a 2Si ∶H 薄膜,然后再用热处理的方法使其转化为纳米晶硅薄膜.这种方法的优点是能制备大面积的薄膜,可进行原位掺杂,成本低,工艺简单,易于批量生产.常规的高温炉退火、金属诱导晶化、快速热退火、区域熔化再结晶等都属于固相晶化法.1.1.1 常规高温炉退火 该方法是在氮气保护下把非晶硅薄膜放入炉腔内退火,使其由非晶态转变为纳米晶态[3].非晶硅晶化的驱动力是晶相相对于非晶相较低的G ibbs 自由能.固相晶化过程主要由晶核的形成及晶核长大两步完成.形核率和生长速率都受温度的影响,所以纳米晶硅薄膜的晶粒尺寸受温度的影响很大.晶硅薄膜的晶粒尺寸除受温度的影响外,与初始非晶硅膜的结构状况也有密切的关系.有研究者采用“部分掺杂法”来增大晶粒尺寸,即在基底上沉积两层膜,下层进行磷掺杂,作为成核层,上层不掺杂,作为晶体生长层,退火后可获得较大的晶粒[4].1.1.2 金属诱导晶化 金属诱导晶化就是在非晶硅薄膜上镀一层金属
水热法合成纳米氧化锌 一、引言 二、实验部分 2.1实验仪器 集热恒温磁力搅拌器山东鄄城永兴仪器厂2（加搅拌子2） X射线衍射仪（DX-2000型）丹东方圆仪器有限公 司 1 光学显微镜 1 恒温干燥箱 1 聚四氟乙烯高压反应釜编号100-25、100-44 2 马弗炉 1 量筒（50ml） 1 烧杯3个100ml、2个150ml 坩埚 1 玻璃棒 1 培养皿 2 抽滤瓶 1 载玻片 2 2.2实验药品 草酸天津市元立化工有限公司分析纯氢氧化钠天津市福晨化学试剂厂分析纯 硝酸锌天津市天大化工试剂厂分析纯 氨水天津市元立化工有限公司25% 无水乙醇天津市风船化学试剂有限公司分析纯
去离子水 2.3实验内容 2.3.1水热合成纳米氧化锌 称取8.9482gZn（NO3).6H2O固体溶解于20ml去离子水中，在充分搅拌条件下缓慢滴加2 5％的浓氨水，至生成的沉淀恰好消失为止( p H≈10 )，得到前驱体溶液(其浓度认为等于Zn的浓度)。将上述溶液转移到聚四氟乙烯内胆的高压釜中，保持其填充度为80％。在180℃下反应3h后，自然冷却至室温。抽滤并收集白色沉淀，然后用去离子水反复冲洗以除去吸附的多余离子，于90℃烘箱中干燥以备表征。 2.3.2草酸高温合成纳米氧化锌 称取3.111gZn（NO3).6H2O溶解于20ml去离子水，在充分搅拌情况下缓慢滴加滴加草酸溶液(1~2d每秒为宜），使之沉淀完毕，搅拌0.5h，进行抽滤，用去离子水和无水乙醇洗涤，放入90℃烘箱干燥2h，然后高温700℃灼烧2h。 2.3.3在玻璃基体上生长纳米氧化锌阵列 （1）晶种层的制备 载玻片衬底先后在稀氢氟酸、氢氧化钠溶液、去离子水和无水酒精中超声清洗，然后放入烘箱中烘干备用。 Z n O种子液配制如下：制备等量的0.001mol/L和0.002mol/L的硝酸锌溶液，于磁力搅拌下分别缓慢滴加稀氨水，直至沉淀消失,在60℃水浴30min获得均匀澄清溶液采用浸渍提拉法在清洁衬底上涂敷Z n O凝胶膜：浸人种子液的浸渍时间为1 min，提拉速度0 .8 5 m m/s,8 0℃烘箱烘干,重复以上操作3次,最后将涂有薄膜的衬底进行热处理5 5 0℃，保温 1.5h 。最终获得晶种膜。 （2）水溶液生长 一定量的硝酸锌和氨水( 2 5 ％) 加入去离子水中。配制20ml的生长液。搅拌均匀并密封，锌浓度范围为0.001mol/L。氨水和硝酸锌的物质的量的比为4:1至11:1，将有晶种层的衬底放人装有生长液的密封反应釜中。于9 0℃水浴中保持6h。硝酸溶液( p H = 0.4 ) 和氨水(2 5 ％) 被用来进行生长液p H值( 8.2~9.8) 的原位二次调整。最后合成的薄膜用去离子水清洗,空气中晾干。 三、结果与讨论 3.1纳米氧化锌的XRD表征谱图 两组纳米氧化锌粉末进行XRD测试，设置扫描范围20°~70°，扫描速度0.1，铜靶波长1.54184?。两者对照谱图如下：
价格是影响顾客购买的重要因素，也是营销活动中最难以确定的因素，定价要求企业既要考虑企业的成产成本，又要考虑顾客对价格的接受程度，而纳米二氧化硅颗粒价格也在随着行情不断变化，具体价格行情可以直接点击官网恒力特新材料进行在线咨询。下面为您介绍下它的相关知识，希望能给您带来帮助。 纳米二氧化硅是无机粉体中的“半边天”，她的微颗粒表面带负电，不但亲水，而且亲和各种粉体，阴阳平衡，流动如水，具有高分散性，是典型的“干粉改性剂” 纳米二氧化硅表面负电性化学活性高，是粉体材料中少有的酸性氧化物。她与碱结合，可在水中速凝固，她在世界瞩目的墨西哥湾漏油事故中，解决了世界性堵漏难题。因此首先出生中国的纳米二氧化硅便成了世界油田的“女神”，因为特轻质，中国石油业又给她取了绰号——“减轻剂”。
纳米二氧化硅在高性能混凝土中添加水泥用量的1～6%，可使抗压强度提高1倍，并可改善混凝土工作性——可塑性、泵送性、保水性、防泌水性、抗渗性、抗冻性等。适量加入水泥中改性使用，她与游离钙结合即生成硅酸钙凝胶，填充水泥石结构缝隙，使短命的水泥混凝土成为耐久的人造石。 纳米二氧化硅复合少量钛白粉、氧化锌等可成为高分散轻质活性补强粉体，加入橡胶中可生产优质飞机、汽车轮胎。配制功能性纳米复合材料，可广泛应用于新型建材、橡塑制品、油漆涂料、玻璃钢、工程陶瓷、纺织人革、胶粘剂、炼钢脱氢剂、水晶制品…… 恒力特新材料是集科技研发、生产、销售为一体的高新技术企业，是国内和华东地区橡胶助剂骨干企业，恒力特牌橡胶防老剂 8PPD-35、BLE、BLE-W、BLE-C、SP、SP-C、AW、DFC-34等系
列，抗疲劳剂PL-600、橡胶耐磨剂SL-A、橡胶助剂EVR、抗热氧剂RW、阻燃剂、橡胶粘合剂HLT-301、HLT-501系列，橡胶促进剂DTDM、DBM系列，橡胶补强剂FH、FHT系列，都得到了轮胎、胶带、胶管及橡胶制品企业的认可。 公司坐落在安徽阜阳颍州经济开发区，生产工艺先进，检测仪器齐全，产品性能稳定，本着“和谐、诚信、奋进”的企业精神，遵循以“过硬的产品、更好的服务”为宗旨，以更好的性价比为橡胶制品行业提供更多、更优的选择。如果您想进一步了解，可以直接点击官网恒力特新材料进行在线咨询。
水热法制备ZnO纳米结构及其应用 摘要纳米结构的ZnO由于具有优异的光、电、磁、声等性能，已经成为光电、化学、催化、压电等领域中聚焦的研究热点之一。不同纳米结构的ZnO其制备方法多种多样，本文着重综述了水热法制备ZnO纳米结构，并探讨了ZnO纳米结构的生长机理和调控，同时展望了ZnO纳米结构在各领域中的最新应用。 关键词ZnO纳米结构水热法生长机理生长调控应用 引言
氧化锌是一种宽禁带直接半导体材料，室温下其禁带宽度为3.37 eV，激子束缚能为60 meV，可以实现室温下的激子发射，产生近紫外的短波发光，被用来制备光电器件，如紫外探测器、紫外激光器等。另外ZnO还具有很好的导电、导热和化学稳定性能，在太阳能电池、传感器和光催化方面有广泛的应用前景。因此成为国际上半导体材料研究的热点之一。而一维半导体材料更由于其独特的物理特性及在光电子器件方面的巨大潜力，备受人们的关注[1, 2]。将纳米ZnO用于电致发光器件中对提高器件性能很有帮助[3]。在基底上高度有序生长的ZnO 纳米结构可制作短波激光器[2]和Graetzel太阳能电池电极[4]，成为人们的研究热点。 目前国内外研究者已成功地合成了多种ZnO纳米结构：Huang等[5]制备出的ZnO纳米铅笔状结构具有尖端和高的比表面积，有望用于场发射微电子器件方面；杨培东[6]、Shingo Hirano[7]小组分别用气相传输法和水热法合成的ZnO纳米线阵列表现出室温紫外激光发射行为，可用来制备紫外纳米激光器；张立德[8]研究小组用简单的热蒸发方法得到了一种ZnO纳米薄片状结构，可用于纳米传感器方面。另外，研究者还制备出ZnO纳米环、纳米带、纳米花和多足状等结构。 合成ZnO纳米结构的方法多种多样，主要有气相沉积法、模板法及催化助溶法、电化学法，其它还有诸如沉淀法、溶胶-凝胶法、多羟基化合物水解法等。近年来水热法制备ZnO纳米结构成为了研究者关注的热点，与其它方法相比，水热法具有设备简单，反应条件温和，可大面积成膜，工艺可控等优点。 1.水热法制备ZnO纳米结构简介及研究新进展 1.1水热法制备ZnO纳米结构简介 水热法是指在特制的密闭反应器(高压釜)中，采用水溶液作为反应体系，通过对反应体系加热加压(或自生蒸汽压)，创造一个相对高温、高压的反应环境，使通常难溶或不溶的物质溶解，并且重结晶而进行无机合成与材料处理的一种方法。经过十多年的发展，水热法逐步发展成为纳米材料制备最常用的方法之一。由于水热法自身的优点和特殊性，在科技高度交叉的21世纪，水热法已不再局限于晶体生长，而是跟纳米技术、地质技术、生物技术和先进材料技术息息相关，水热法的研究也向深度与广度发展。
1前言 1.1纳米二氧化硅的发展现状及前景 纳米材料是指微粒粒径达到纳米级(1～100nm)的超细材料。当粒子的粒径为纳米级时，其本身具有量子尺寸效应和宏观量子隧道效应等，因而展现出许多特有的性质，应用前景广阔。纳米SiO 是极具工业应用前景的纳米材料，它的应用领域十分广泛，几乎 2 粉体的行业。我国对纳米材料的研究起步比较迟，直到“八五计涉及到所有应用SiO 2 划”将“纳米材料”列人重大基础项目之后，这方面的研究才迅速开展起来，并取得了令人瞩目的成果。1996年底由中国科学院固体物理研究所与舟山普陀升兴公司合作，成 [1]，从而使我国成为继美、英、日、德功开发出纳米材料家庭的重要一员——纳米SiO 2 国之后，国际上第五个能批量生产此产品的国家。纳米SiO 的批量生产为其研究开发提 2 供了坚实的基础。 目前，我国的科技工作者正积极投身于这种新材料的开发与应用，上海氯碱化工与华东理工大学[2]建立了连续化的1000t／a规模中试研究装置，开发了辅助燃烧反应器等核心设备，制备了性能优良的纳米二氧化硅产品，其理化性能和在硅橡胶制品中的应用性能，已经达到和超过国外同类产品指标。专家鉴定认为，纳米二氧化硅氢氧焰燃烧合成技术、燃烧反应器和絮凝器等关键设备及应用技术具有创新性，该成果总体上达到国际先进水平，其中在预混合辅助燃烧新型反应器和流化床脱酸两项核心技术方面达到了国际领先水平，对于突破国际技术封锁具有重大价值。但总地来讲，我国纳米SiO 的生 2 产与应用还落后于发达国家,该领域的研究工作还有待突破。 1.2 纳米二氧化硅的性质[3]~[5] 纳米二氧化硅是纳米材料中的重要一员，为无定型白色粉末，是一种无毒、无味、无污染的非金属材料。微结构呈絮状和网状的准颗粒结构，为球形。这种特殊结构使它具有独特的性质： 纳米二氧化硅对波长490 nm以内的紫外线反射率高达70%～80%，将其添加在高分子材料中，可以达到抗紫外线老化和热老化的目的。 纳米二氧化硅的小尺寸效应和宏观量子隧道效应使其产生淤渗作用，可深入到高分子链的不饱和键附近，并和不饱和键的电子云发生作用，改善高分子材料的热、光稳定性和化学稳定性，从而提高产品的抗老化性和耐化学性。 纳米二氧化硅在高温下仍具有强度、韧度和稳定性高的特点，将其分散在材料中，
收稿日期：2014-06-19。收修改稿日期：2015-01-05。国家自然科学基金(NO.50432030、U1304110)资助项目。 ＊ 通讯联系人。E -mail ：liuhairui1@https://www.doczj.com/doc/749631988.html, ZnS 纳米球的水热法制备及其光催化性能研究 刘海瑞＊,1,2 方力宇2 贾 伟2 贾虎生2 (1河南师范大学物理与电子工程学院，新乡453007)(2太原理工大学材料科学与工程学院，太原 030024) 摘要：在表面活性剂十六烷基三甲基溴化铵(CTAB)的辅助下，以乙酸锌为锌源，硫脲(NH 2)2CS 为硫源，使用水热法通过改变反应时间，成功制备了不同粒径的ZnS 球状颗粒。利用X 射线衍射(XRD)、扫描电子显微镜(SEM)、X -射线能谱，高分辨透射电子显微镜(HRTEM))、紫外可见分光光谱和光致发光谱(PL)等测试手段对样品的晶体结构、形貌、光学性质进行了分析。通过对不同粒径的ZnS 纳米颗粒对亚甲基蓝的光催化降解的催化活性进行了评估。实验结果表明：在表面活性剂CTAB 的作用下，随着反应时间的增加，生成的ZnS 晶核生长成纳米颗粒，然后ZnS 纳米颗粒将进一步发生团聚从而形成平均粒径超过500nm 的ZnS 纳米球，但制备的ZnS 产物的晶体结构均为立方纤锌矿结构。随着ZnS 粒径的增加，样品的紫外吸收峰从418nm 逐渐蓝移到 362nm ，而PL 发射峰位的峰强随着粒径的增大而增强。光催化结果显示，反应12h 制备的ZnS 纳米球的光催化性能最佳。 关键词：ZnS ；球状结构；水热法；光催化中图分类号：O643.3 文献标识码：A 文章编号：1001-4861(2015)03-0459-06 DOI ：10.11862/CJIC.2015.074 Fabrication of ZnS Nanoparticles with Enhanced Photocatalytic Activity by Hydrothermal Method LIU Hai -Rui ＊,1,2FANG Li -Yu 2JIA Wei 2JIA Hu -Sheng 2 (1College of Physics and Electronics Engineering,Henan Normal University,Xinxiang,Henan 453007,China )(2College of Materials Science and Engineering,Taiyuan University of Technology,Taiyuan 030024,China ) Abstract:Under the role of CTAB,different size ZnS spherical -like particles were fabricated by hydrothermal method.The crystal structure,morphology,composition and optical property of the samples were characterized by X -ray diffraction (XRD),scanning electron microscopy (SEM),high resolution transmission electron microscopy (HRTEM),X -ray energy spectrum (EDS),UV -Vis absorption spectrum and photoluminescence spectrum (PL).Photocatalytic activities were evaluated by degradation of MB solution.The results show that ZnS nanoparticles were formed by aggregation of crystal nucleus under the role of CTAB.With the increase of reaction time,the size of ZnS particles increased to 500nm,however,the crystal structure of product has no change.With the increase of particle size,the UV -Vis absorption peak of samples shifted from 418to 362nm and the PL intensity further increased.Finally,the photocatalytic activity presented that fabricated ZnS nanoparticles with reaction time 12h showed best photcatalytic performance. Key words:ZnS;spherical structure;hydrothermal method;photocatalysis 第31卷第3期2015年3月 Vol ．31No ．3459-464 无机化学学报 CHINESE JOURNAL OF INORGANIC CHEMISTRY
制备硅纳米晶体新的有效方法 作者：Belle Dumé，李清旭译 引用网址：https://www.doczj.com/doc/749631988.html,/eprint/abs/1999.html 相关网址：https://www.doczj.com/doc/749631988.html,/articles/news/8/10/14/1 摘要/内容： 美国Minnesota 大学的工程人员发明了一种室温下在等离子体中制造硅纳米颗 粒的新方法。新方法解决了现有的基于等离子体的制备方法中的问题，可以制 造出尺寸相同的纳米颗粒。研究人员说这种晶体颗粒可以用到新的电子器件中，譬如说单个纳米颗粒晶体管(A Bapat et al. 2004 https://www.doczj.com/doc/749631988.html,/abs/physics/0410038)。 相对于非晶态（无定型）硅来说，晶态硅有许多好的特性，可以用于高速电子 学（high-speed electronics）中，不过现有的等离子体合成技术（plasma synthesis techniques）总是得到非晶态（无定型）硅。并且得到的纳米颗粒 或者存在很多缺陷，或者尺寸变化范围很大。 Uwe Kortshagen和他的同事们所发展的新技术没有这些缺点，可以得到真正意 义上的无缺陷晶态纳米颗粒，并且颗粒的尺寸只在一个较小的范围内变化。 Kortshagen和合作者在一个窄的约23厘米长的石英管里注入95%的氦和氩以及5%的硅烷（SiH4），然后他们在距基电极10厘米距离的环状电极上加上一个13.56兆赫200瓦的功率,可以得到不稳定的由明亮的等离子体滴构成的细丝状的等离子体。现有的等离子体合成法使用稳定均匀的等离子体。
等离子体中的高能电子使硅烷分解得到硅原子，并且重组得到硅颗粒。利用透射电子显微镜（TEM）可以发现得到的纳米颗粒尺寸介于20-80纳米之间，并且主要呈立方体形状。 “现在，我们还没有完全明白晶体硅的形状为什么这么好，或者为什么会形成晶体。”Kortshagen 告诉 PhysicsWeb，“不过，我们相信细丝状的等离子体起到了重要作用，它把硅颗粒加热到比周围气体高几百度的温度，颗粒中的原子可以进行自我调节，找到一个能量有利的形态。” 研究人员现在希望把这种方法推广到其他像砷化镓，氮化镓这些有商用价值的材料的制备中。
水热法制备锥状ZnO纳米线阵列及其光电性研究水热法制备锥状ZnO纳米线阵列及其光电性研究 摘要 ZnO是一种在光电领域中具有重要地位的半导体材料。采用聚乙二醇(PEG(2000))辅助的水热合成法制备出了粒径较为均匀的锥状氧化锌纳团线阵列, 并用SEM、XRD对其进行了表征。实验结果表明,表面活性剂(PEG22000)和氨水的加入量对ZnO纳米线阵列的形貌有直接的影响;分析出了不同体系中的化学反应过程及生长行为，研究了衬底状态、生长溶液浓度、生长时间、pH值等工艺参数对薄膜生长的影响，并对薄膜柱晶等特殊形貌晶体的生长机理进行了探讨。研究表明：薄膜的晶粒成核方式主要为异质成核，柱晶的生长方式为层-层生长。生长的ZnO柱晶的尺寸和尺寸分布与晶种层ZnO晶粒有着相同的变化趋势。随着生长液浓度的增加，ZnO棒晶的平均直径明显增大。生长体系长时间放置，会导致二次生长，形成板状晶粒。NH3·H2O生长系统，可以调节pH值来控制薄膜的生长。对于碱性溶液体系，ZnO合适的生长温度为70~90℃，通过调节温度，可以改变纳米棒的生长速率。 关键词：ZnO薄膜,低温,水热法,薄膜生长
HYDROTHERMAL SYNTHESIS OF ZnO NANOWIRE ARRAYSCONE AND OPTOELECTRONIC RESEARCH ABSTRACT ZnO is an important area in the status of photovoltaic semiconductor material.Polyethylene glycol (PEG (2000)) assisted hydrothermal synthesis were prepared by a more uniform particle size of zinc oxide nano cone line array group and use SEM, XRD characterization was carried out. The results show that surfactant (PEG22000) and ammonia addition on the morphology of ZnO nanowire arrays have a direct impact; analyze the different systems of chemical reactions and growth behavior of the state of the substrate, growth concentration, growth time, pH, and other process parameters on film growth, and morphology of thin film transistors and other special column crystal growth mechanism was discussed. The results show that: the film grain nucleation is mainly heterogeneous nucleation, crystal growth patterns column for the layer - layer growth. The growth of ZnO crystal size and column size distribution of ZnO grain and seed layer have the same trend. With the increase in the growth of concentration, ZnO rods significantly increased the average diameter of crystal.Growth system extended period of time will lead to secondary growth, the formation of tabular grains. NH3 ? H2O growth system, you can adjust the pH value to control the film growth. The alkaline solution system, ZnO is a suitable growth temperature 70 ~ 90 ℃, by adjusting the temperature, can change the growth rate of nanorods. Key words：ZnO films, low temperature, hydrothermal method, thin film growth
在我们的认知里，厂家进行直接销售是有利于顾客进行购买的，首先没有了繁琐的分销渠道费用，也少了中间商赚取差价的机会，所以其性价比高的价格优势得以体现，也让很多顾客一直在寻找厂家价格。下面由纳米二氧化硅厂家恒力特新材料为您介绍下它的相关知识，能够帮助您在购买此产品时有全面的认知。 纳米二氧化硅在高性能混凝土中添加水泥用量的1～6%，可使抗压强度提高1倍，并可改善混凝土工作性——可塑性、泵送性、保水性、防泌水性、抗渗性、抗冻性等。适量加入水泥中改性使用，她与游离钙结合即生成硅酸钙凝胶，填充水泥石结构缝隙，使短命的水泥混凝土成为耐久的人造石。 纳米二氧化硅复合少量钛白粉、氧化锌等可成为高分散轻质活性
补强粉体，加入橡胶中可生产优质飞机、汽车轮胎。配制功能性纳米复合材料，可广泛应用于新型建材、橡塑制品、油漆涂料、玻璃钢、工程陶瓷、纺织人革、胶粘剂、炼钢脱氢剂、水晶制品…… 纳米二氧化硅的“海绵体”轻质特性，可作为活性载体，分散吸纳各种颜料、药物、化工材料等，生产各种功能材料制品，如隐形飞机涂料、防辐射抗紫外线材料、屏蔽电磁波、降解涂料中甲醇等有害物，抗菌、抗静电、导电、储能电池、医药制药赋形、化工催化促进、纺织保健……。 纳米二氧化硅是新材料革命的“女神”，也是“为民造福的基础原材料”，电子时代的战备物资、太阳能电池的储能材料。它的用途和潜在市场可改变一个国家，一个地区的经济结构！ 恒力特新材料是集科技研发、生产、销售为一体的高新技术企业，是国内和华东地区橡胶助剂骨干企业，恒力特牌橡胶防老剂 8PPD-35、BLE、BLE-W、BLE-C、SP、SP-C、AW、DFC-34等系
文章编号:1007-967X(2004)06-0034-04 室温固相合成纳米硫化锌及其性能研究Ξ 马国峰,邵忠宝,姜 涛 (东北大学化学系,辽宁沈阳110004) 摘 要:用醋酸锌和硫化钠为原料,室温固相法合成纳米ZnS,用紫外吸收光谱,红外光谱,X-ray 衍射分析(XRD),透射电镜(TE M)对产物结构、组成、大小、形貌进行表征。结果表明在加 入一定量的分散剂后,制备的纳米硫化锌粒子的平均粒径约20nm,分散性好,晶相单一, 属于立方晶系。在紫外吸收光谱中纳米硫化锌吸收峰蓝移,吸收峰从340nm减少到265 nm。从红外光谱可知,该粉体无红外吸收峰,具有红外透明性。讨论了不同的分散剂,煅 烧温度等条件对硫化锌粒度的影响。少量硫化锌作为助燃剂添加到重油-煤-水三元混 合流体燃料中,明显提高了重油-煤-水三元混合流体燃料燃烧性能。 关键词:固相反应;纳米硫化锌;助燃剂 中图分类号:TF123.23 文献标识码:A 纳米材料及技术是材料科学领域一个非常重要的研究方向,现已成为国际科学前沿和世界性的研究热潮[1,2]。已有研究表明,纳米材料具有独特的表面效应、体积效应及宏观量子隧道效应等,在电学、磁学、光学、力学、催化等领域呈现出许多优异的性能,有着广阔的应用前景[3]。合成纳米材料的有多种方法,但反应均需要高温,并使用大量的有机溶剂,,设备费用高,颗粒均匀性差,粒子易粘结或团聚等[4],室温、近室温固相反应合成纳米材料近年来取得很大的进展[5]。它的突出特点是操作方便,合成工艺简单,转化率高,粒径均匀,且粒度可控污染少,可避免或减少液相中易出现的硬团聚现象,以及由中间步骤和高温反应引起的粒子团聚现象。ZnS是一种非常重要且应用广泛的半导体材料,主要应用于电子工业、国防军工、化学化工等诸多领域[6]。目前纳米ZnS的制备方法主要有元素直接反应、离子交换反应、微乳液法、水热法、溶剂热合成等[7～9]。本文利用室温固相合成法合成纳米硫化锌,并探讨了反应物反应前的处理,加入不同的分散剂和不同煅烧温度对ZnS粒径及分散性的影响,以及在重油-煤-水三元混合流体燃料中加入少量的纳米ZnS可以提高其燃烧性能,从而表明纳米ZnS 作为助燃剂有研究价值。 1 实验部分1.1 实验试剂 醋酸锌、硫化钠、氯化钠、乙二醇、无水乙醇、氨水均为分析纯。其中醋酸锌带2个结晶水,硫化钠带9个结晶水,重油取自葫芦岛市炼油五厂。各种盐在使用前,用化学法对金属含量进行标定。 1.2 实验内容 1.2.1 醋酸锌的处理 配置一定量的醋酸锌饱和溶液,加热蒸发掉一部分水,立即放入冰水中使其重结晶,然后抽滤。1.2.2 纳米硫化锌粉体的制备 按化学计量比称取一定量处理过的醋酸锌和研磨过的硫化钠放入玛瑙研钵中混合均匀,充分研磨30min,使其完全反应,用去离子水和无水乙醇分别洗涤两次,并放入稀氨水中洗涤一次,抽干,放在干燥箱中800℃干燥10h后,研磨,得到白色产物,放入马沸炉煅烧。 在反应中掺入适量的氯化钠或溶剂如乙二醇作为分散剂制备纳米硫化锌,其余过程与上述相同。1.2.3 重油-煤-水三元混合燃料的制备 向稳定性较好的乳化重油中加入适量的煤粉、分散剂、助燃剂,得到新型重油-煤-水三元混合流体燃料。 1.3 纳米材料的表征 物相分析在Philips analyti-cal X-Ray Service 第20卷第6期2004年12月 有 色 矿 冶 N ON-FERR OUS MINING AN D METALLURG Y V ol.20.№6 December2004 Ξ收稿日期:2004-05-10 作者简介:马国峰(1979—),男,东北大学硕士研究生。
纳米二氧化硅 简介： 为相关工业领域的发展提供了新材料基础和技术保证。由于它在磁性、催化性、光吸收、热阻和熔点等方面与常规材料相比显示出特异功能，因而得到人们的极大重视。一、XZ-G01二氧化硅产品的主要技术指标，含量：99.99 % 水分≤0.01 二、XZ-G01二氧化硅用途1、涂料及饱和树脂的增稠剂和触变剂；2、平光剂：家具漆有向亚光方向发展的趋势，列沦清漆或色漆均可使用超细二氧化硅凝胶产品作为平光剂，另外卷材涂层、PVC、塑料壁纸、雨衣帐篷等平光剂亦可使用此类产品。3、聚乙烯、聚苯烯、无毒聚氯乙稀薄膜抗阻塞剂/开口剂。三．XZ-G01二氧化硅在高分子工业中的应用它广泛地应用于橡胶、塑料、电子、涂料、陶（搪）瓷、石膏、蓄电池、颜料、胶粘剂、化妆品、玻璃钢、化纤、有机玻璃、环保等诸多领域。 应用范围 由于纳米二氧化硅SP30具有小尺寸效应，表面界面效应、量子尺寸效应和宏观量子遂道效应和特殊光、电特性、高磁阻现象、非线性电阻现象以及在高温下仍具的高强、高韧、稳定性好等奇异性，纳米二氧化硅可广泛应用各个领域，具有广阔的应用前景和巨大的商业价值。纳米二氧化硅是应用较早的纳米材料之一，关于纳米SiO2在橡胶改性、工程塑料、陶瓷、生物医学、光学、建材、树脂基复合材料改性中的应用已有过许多报道，这里重点介绍纳米氧化硅SP30）在其他领域的应用进展。 4.1在涂料领域 纳米二氧化硅具有三维网状结构，拥有庞大的比表面积，表现出极大的活性，能在涂料干燥时形成网状结构，同时增加了涂料的强度和光洁度，而且提高了颜料的悬浮性，能保持涂料的颜色长期不退色。在建筑内外墙涂料中，若添加纳米氧化硅，可明显改善涂料的开罐效果，涂料不分层，具有触变性、防流挂、施式性能良好，尤其是抗沾污染性能大大提高，具有优良的自清洁能力和附着力。纳米SiO2还可与有机颜料配用，可获得光致变色涂料，M．P ．J ．Peeters 等用溶胶凝胶法合成了含纳米二氧化硅SP30的全透明的耐温涂料 H．Schmidt 等合成了很厚的含纳米SiO2的涂料，并耐高温，在500℃下没有出现裂缝，Fayna Mamme ri等合成了P MMA- SiO2纳米涂料。明显增强了涂料的弹性和强度。
PINGDINGSHAN UNIVERSITY 科技文献检索与论文写作 论文题目：硫化锌纳米材料制备方法及展望 班级：12级化工二班 院系：化学化工学院 学号：121170243 姓名：孙明华 指导老师：曹可生
硫化锌纳米材料制备方法及展望 学号：121170243 姓名：孙明华专业：化学工程与工艺年级：12级班级：化工（2）班摘要：对硫化锌纳米材料的研究进行了综述，阐述了Zns纳米材料的制备方法研究现状和发展前景，并对这些方法和成果进行了比较。 关键词:纳米材料，制备方法，前景展望 ZnS作为一种重要的宽带隙半导体材料，具有一些独特的电学、荧光和光化学性能，在平面显示器，电致发光器件，红外窗口，发光二极管，激光器，光学涂料，光电调节器，光敏电阻，场效应晶体管，传感器，光催化等许多领域有着广泛的应用前景。当ZnS 粒子的粒径尺寸小于它的激子的波尔半径时，就会呈现出明显的量子尺寸效应，同时它的光电性能也会随着尺寸和形貌的变化而变化。近年来，纳米级结构的ZnS特别是准一维纳米结构的研究，受到材料科学家的广泛关注，关于ZnS 纳米结构的制备、形态结构、性质及应用等方面开展了广泛研究，出现了多种不同的制备技术。制备方法主要有水热（溶剂热）法，界面合成法，辐射合成法，聚合物网络合成法，模板技术，等，并用这些方法合成了均匀一致的ZnS纳米棒，纳米线纳米带和纳米管。溶剂热方法是一种制备无机纳米材料( 如氧化物、硫化物、磷酸盐、沸石、金刚石等) 的有效方法。因此采用溶剂热法合成具有高度有序和很高的长径比的ZnS纳米结构阵列，对此进行深入研究不仅具有重大的理论意义，而且具有巨大的潜在应用价值。 1.水热( 溶剂热) 法简介 水热( 溶剂热) 法是指在高温、高压反应环境中，以水( 有机溶剂) 为反应介质，使通常难溶或不溶的物质溶解并进行重结晶。通过水热反应可以完成某些有机反应或对一些危害人类生存环境的有机废弃物进行处理以及在相对较低的温度下完成某些陶瓷材料的烧结等。水热法具有反应条件温和、污染小、成本较低、易于商业化、产物结晶好、团聚少、纯度高及可通过调节反应温度、压力、溶液成分和pH 等因素来达到有效地控制反应和晶体生长的目的等特点。 １．1 水热法 水热法是指在密封压力容器的高温高压环境中，以水作为反应介质，制备研究材料的一种方法。低温（温度在２５～２００℃之间）水热合成反应更加受到人们的青睐，即可得到处于非平衡状态的介稳相物质[1]，又可使反应温度较低有利于产品的大规模工业生产。 在水热条件下，水既是溶剂，又是矿化的促进剂，同时还是压力传递的媒介物。与其它湿化学方法相比，主要具有以下两方面优越之处：（１）水热法避免了高温处理而可直接得到结晶良好的粉体，工艺简单，不易团聚等。研究表明，制备出的粒子形状规则且粒度分布窄、纯度高、分散性好、晶型好且可控制、生产成本低。（２）产物的形貌、晶相及纯度与水热反应条件有很大的相关性，可以通过改变反应条件来对产物的这些性质进行调控。 YU W等首先在铜板上镀锌晶种，然后采用简单的水热法在纳米晶锌层上通过醋酸锌和硫脲反应合成了ZnS纳米阵列。实验表明纳米晶锌不仅是水热反应的晶种，而且作为反应物提供硫离子，具有很高的活性。尤其是水热反应在95℃低温和1ｈ短时间条件下完成的，操作简单方便。而且这样制备出的Zns纳米棒具有形貌整齐、长径比高等特点，给未来场致发射的应用带来了很大的潜能。 水热法合成ZnS的实验中，TEM图像显示，表面光滑的Zns纳米棒直径大约20nm，长径比也较高。由选区电子衍射（SATD）图可以得出，在Zns纳米棒上聚焦电子束显示出散布的环，证明ZnS纳米棒是多晶的。TEM图像表明六边形的CuS纳米盘有２个主要的方向，一个是在平的基底上，另一个是垂直于基底。 １.２溶剂热法
纳米硅指的是直径小于5纳米（10亿（1G）分之一米）的晶体硅颗粒。 编辑本段纳米硅粉 纳米硅粉具有纯度高，粒径小，分布均匀等特点。比表面积大，高表面活性，松装密度低，该产品具有无毒，无味，活性好。纳米硅粉是新一代光电半导体材料，具有较宽的间隙能半导体，也是高功率光源材料。 主要用途： 可与有机物反应，作为有机硅高分子材料的原料 金属硅通过提纯制取多晶硅。 金属表面处理。 替代纳米碳粉或石墨，作为锂电池负极材料，大幅度提高锂电池容量编辑本段纳米硅防水剂 一、性能特点 白色乳液，无毒，无刺激味,不燃烧，PH值12，密度1.15～1.2。用于砖瓦、水泥、石膏、石灰、涂料、石棉、珍珠岩、保温板等基面上具有优异的防水抗渗效果。有防止建筑物风化、冻裂及外墙保洁、防污、防霉、防长青苔之功能；质量可靠，耐久性好，耐酸碱，耐候性优良，对钢筋无锈蚀，且使用安全，施工方便。砂浆抗渗性能≥S14，混凝土抗渗性能≥S18。技术性能符合JC474－1999[砂浆、混凝土防水剂]标准及JC/T902-2002标准 二、使用方法 1、喷涂施工： 使用前先将基面清理干净（特别是油污、青苔），将纳米硅防水剂加8倍清水搅拌均匀，用喷雾器或刷子直接在干燥的基面上施工，纵横至少连续两遍（上一遍没干时施工第二遍），对于1:2.5砂浆的毛面，大约可渗透1mm深，有效寿命可达5~10年，每公斤本剂每遍可施工约40~50m2,施工后24小时内不得受雨淋水浸，4℃以下停止施工。常温下干燥后即有优良的防水效果，一周后效果更佳（冬季固化时间较长）。试验表明：固化后的防水试块高温300℃反复锻烧20次及－18℃反复冷冻20次后，防水效果没有明显变化。稀释液现配现用，当天用完。 2、防水砂浆施工： 清理基层泥沙、杂物、油污等，灰砂比控制在1:2.5～3（425＃硅酸盐水泥、中砂含泥量小于3％）；纳米硅防水剂加水8－15倍（体积比）可直接用于配制防水砂浆，水灰比≤0.5，实际净防水剂用量占水泥的3～5％。
第26卷 第8期2005年8月 半 导 体 学 报 CHIN ESE J OURNAL OF SEMICONDUCTORS Vol.26 No.8 Aug.,2005 3教育部博士点基金资助项目(批准号:20040532014) 裴立宅 男,1977年出生,博士研究生,从事硅及相关纳米材料的研究.Email :lzpei1977@https://www.doczj.com/doc/749631988.html, 唐元洪 通信联系人,男,1965年出生,教授,博士生导师,从事纳米信息材料的研究.Email :yhtang @https://www.doczj.com/doc/749631988.html, 2004212214收到,2005201224定稿 Ζ2005中国电子学会 硅纳米管的水热法合成与表征 3 裴立宅 唐元洪 陈扬文 郭 池 张 勇 (湖南大学材料科学与工程学院,长沙 410082) 摘要:采用水热法成功合成了新型的硅纳米管一维纳米材料,并采用透射电子显微镜、选区电子衍射分析、能量色散光谱及高分辨透射电子显微镜对合成的硅纳米管进行了表征.研究表明硅纳米管是一种多壁纳米管,为立方金刚石结构,生长顶端呈半圆形的闭合结构,由内部为数纳米的中空结构,中部为晶面间距约0131nm 的晶体硅壁层,最外层为低于2nm 的无定形二氧化硅等三部分组成.关键词:硅纳米管;水热法;结构;表征 PACC :6146;8160C 中图分类号:TN30411 文献标识码:A 文章编号:025324177(2005)0821562205 1 引言 自从碳纳米管[1]及硅纳米线[2,3]等一维纳米材 料被成功合成后,立刻引起了诸多领域科学家的极大关注与浓厚兴趣,一维纳米材料的研究成为了当今基础和应用研究的热点.碳纳米管能否具有金属或半导体特性取决于纳米管的石墨面碳原子排列的螺旋化方向[4,5],然而到目前为止,还没有人成功制备出金属或半导体碳纳米管,因此虽然碳纳米管作为场效应晶体管(FET )及纳米电子集成电路的研究已有报道[6,7],但是碳纳米管在应用上还有很大的局限性.同时由于硅纳米一维材料与现有硅技术极好的兼容性,使其具有代替碳纳米管的潜力.目前已经采用物理及化学方法成功合成了硅的实心一维纳米材料———硅纳米线[8,9],但是由于元素硅的硅键为sp 3杂化,而不是易于形成管状具有石墨结构的sp 2杂化,所以硅的中空一维纳米材料,硅纳米管难于合成.因此,目前在硅纳米管,尤其是自组生长的硅纳米管的合成方面仍是一个极具挑战性的难题.对硅纳米管模型进行理论研究表明硅纳米管可以稳定存在,同时也发现稳定的硅纳米管结构总是具有 半导体性能[10,11].最近Sha 等人[12]以纳米氧化铝沟道(NCA )为衬底模板,以硅烷为硅源、金属Au 为催化剂,于620℃,1450Pa 时通过化学气相沉积催化生长了直径小于100nm 的硅纳米管;J eong 等人[13]在617×10-8Pa 的真空分子束外延生长(MB E )室中于400℃在氧化铝模板上溅射硅原子或硅团簇,并于600或750℃氧化处理后制备了直径小于100nm 的硅纳米管.虽然目前模板法可以制得硅纳米管,但是此法制备过程较复杂,需要模板及金属催化剂,同时实质上所得硅纳米管是硅原子在模板内壁无序堆积形成的. 水热法是制备纳米粉末的常用方法,对于制备具有一维结构的纳米材料鲜有报道.水热法成功合成了碳纳米丝及碳纳米管[14,15]表明,此法在制备一维纳米材料方面也有极大的应用潜力.水热法具有成本低廉、容易操作控制及可重复性好等特点.本文报道在没有使用催化剂及模板的前提下,采用高压反应釜,在超临界水热条件下合成了自组生长的一维纳米硅管,并用TEM ,EDS ,SA ED 和HR TEM 对其结构及成分进行了表征.这是一种真正意义上的硅纳米管,对于组装纳米器件具有重大的应用与研究意义.