低温低碱浓度条件下水热法制备锆钛酸铅粉体

以Pb(NO3) 2、ZrOCl2·8H2O 和TiCl4作为原料,NaOH作为矿化剂,水热合成锆钛酸铅粉体.系统研究了物质的量比Pb/(Zr,Ti)、矿化剂NaOH浓度、反应温度、反应时间4个因素对PZT晶相形成和粉体形貌的影响.结果表明Pb/(Zr,Ti)在1.7～2.0,NaOH的浓度为1 mol/L、反应温度为200 ℃、时间2 h的水热条件下,可以合成结晶良好的Pb(Zr,Ti)O3粉末.     

引入晶种水热合成氧化铝微粉的工艺与性能

以硝酸铝和氨水沉淀所得的氢氧化铝为前驱物，加入矿化剂和晶种，在水热条件下，保温3～10h，可以制出纳米级的氧化铝微粉。研究了反应条件，如前驱物浓度、矿化剂浓度、晶种添加量、反应温度和保温时间等对水热合成过程的影响，从而得到了最佳工艺参数。用XRD，SEM分析了粉末的晶型与形貌，并研究了用该法制得的氧化铝粉烧结性能，在1550℃下保温烧结2h其相对密度可达97％。以该氧化铝为原料可制备出性能良好的SrAl2O4：Eu，Dy^3＋长余辉发光粉。     

浓海水制备氢氧化镁颗粒的水热改性

将模拟浓海水和NaOH直接沉淀制备的Mg(OH)2水热处理得到Mg(OH)2阻燃剂粉体,考察了矿化剂和温度对其晶体形貌、结晶性及分散性的影响. 结果表明,在实验温度范围内,碱类矿化剂对晶体形貌的改善优于氯盐矿化剂;矿化剂浓度和水热温度越高,对晶体形貌改善越好,晶体粒径及厚度增加越快,且可减小晶体极性和微观内应变,提高结晶度和分散性. 在水热时间8 h、温度200℃、4.0 mol/L NaOH溶液为矿化剂条件下,可制备出粒度分布均匀、平均粒径约为0.250 mm、厚度约61 nm、团聚指数约为10.95的阻燃型Mg(OH)2.     

钛酸铋纳米粉体的水热合成及表征

采用分析纯Bi(NO3)3·5H2O和TiO2为原料,以NaOH 为矿化剂,用水热法合成了钛酸铋纳米粉体.讨论了水热反应温度和晶化时间对钛酸铋粉体结构和形貌的影响.研究结果表明,随着水热温度的提高及晶化时间的延长,晶体结晶程度提高;在140～180 ℃和30～72 h的水热条件下,合成了纯的Bi4Ti3O12粉体,其主要由方形片状的纳米晶组成,为典型的钙钛矿结构.并结合实验结果探讨了钛酸铋的水热合成机理.     

醇对低温水热合成四方相钛酸钡的影响

以Ba(OH)2·8H2O和Ti(OC4H9)4为原料,氨水为矿化剂,以不同醇/水混合溶剂作为分散介质,在180℃下反应120 h,水热合成四方相钛酸钡粉体,研究不同醇对粉体的影响,并通过XRD、TEM、IR及激光纳米粒度分析对粉体进行了表征.结果表明以一元醇为溶剂有利于合成四方相钛酸钡,其中又以乙醇为最优,以乙醇/水为溶剂合成的四方相钛酸钡粉体的c/a最大可达1.0090,且粉体纯度高,粒径分布狭窄,晶粒形貌发育完整,呈现球形和四方形.     

钒酸镧纳米棒的水热合成

以La(NO3)3和Na3VO4为原料,水热合成了LaVO4纳米棒.研究了EDTA用量、水热温度对LaVO4纳米棒结构和形貌的影响.用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对产物进行了表征.结果表明,产物为单一四方锆石型结构的钒酸镧棒,EDTA的用量和水热温度均对产物钒酸镧的形貌有一定的影响.     

水热法低温合成α-Al2O3粉体的影响因素

以工业Al(OH)3为原料,通过引入晶种和矿化剂,用水热法低温合成α-Al2O3粉体.研究了固相含量、原料粒度、水热温度、保温时间、晶种加入量、矿化剂种类等因素对α-Al2O3产率和产物晶粒形貌的影响.结果表明:随固相含量的增加,产物的收率增加,当固相含量增大到8%(质量分数,下同)时,产物的收率开始降低;原料粒度从16 μm减小到2.5μm时,产物的收率增大,当原料粒度减小到1.5μm,产物的收率变化不明显;随着水热温度的升高、水热时间的延长,α-Al2O3含量相对增多,晶粒发育渐趋完善:晶种的引入有效地降低了α-Al2O3成核的活化能,有利于α-Al2O3形成;矿化剂的种类对水热合成α-Al2O3的作用效果差别很大,加入矿化剂KBr更有利于α-Al2O3生成和晶体发育.发育完善的α-Al2O3呈六方柱状,晶体显露{0001}和{11 2 0}面族.最佳的实验工艺条件为:固相含量5%,反应温度390℃,保温时间2h,晶种加入量5%质量分数),填充度40%(体积分数),矿化剂KBr加入量0.5mol/L.     

氧化亚铜纳米棒的合成与表征

利用溶剂热法,以五水硫酸铜和氢氧化钠为原料,乙醇为还原剂,在乙醇与去离子水的混合溶剂中,140 ℃条件下溶剂热处理6～10 h制得了不同长径比的氧化亚铜纳米棒.利用X射线粉末衍射仪(XRD)及高分辨透射电镜(HRTEM)对合成产物进行了物相与形貌分析.检测结果显示合成的纳米棒结晶程度良好,尺寸较为均匀.在实验中还发现反应温度与溶剂中的含水量是影响乙醇还原性的主要因素.     

水热合成技术的研究和应用──Ⅳ.钛酸锶晶体粉末的制备

本文以Sr（OH）2和TiO（OH）2作为水热合成SrTiO3晶体粉末的前驱物，讨论并选定制备前驱物的化工原料，并对水热合成SrTiO3晶体粉末的条件：KOH浓度、温度和时间进行了考察.结果表明150～200℃，1h均可有效合成．200℃下水热20～60min产物的X光衍射特征峰高无明显差别；水热介质中KOH浓度从0.1～1.0mol／L区域内对合成无大的影响；最后初步讨论了SrTiO3晶体粉末的合成机理并合理解释了实验结果.     

Zn0.95Fe0.05O稀磁半导体粉体的制备与表征

采用水热法合成Zn_(0.95)Fe_(0.05)O稀磁半导体,通过试验及XRD、FE-SEM对合成的粉体进行分析,在水热合成法合成条件200℃保温24 h、矿化剂NaOH浓度3 mol/l、填充度为60%下,制备出的Zn_(0.95)Fe_(0.05)O纳米晶体发育完全,粒度分布均匀。是合成Zn_(0.95)Fe_(0.05)O纳米晶体的理想方法之一。     

Synthesis of Porous α-Fe2O3 Nanorods as Catalyst Support and A Novel Method to Deposit Small Gold Colloids on Them

Two novel methods, one for preparation of porous α-Fe₂O₃ nanorod catalyst support and another for the deposition of gold (Au) particles on the catalyst support with high efficiency and high dispersion, were reported. In the former, FeO(OH) nanorods were first prepared by a mild hydrothermal synthesis using tetraethylammonium hydroxide (TEAOH) as the structure director. The FeO(OH) product was then converted to porous α-Fe₂O₃ nanorods via calcination at 300 °C. During this calcination, pores with a size distribution in the range of 1–5 nm were generated by removal of TEAOH molecules. By employing our invented Au colloid-based and sonication-assisted method, in which lysine was used as the capping agent and sonication was employed to facilitate the deposition of the Au particles, we were able to deposit very small Au particles (2–5 nm) into these pores. This method is rapid as the reaction/deposition is completed within 1 min. The prepared Au/α-Fe₂O₃-nanorod catalyst exhibited much higher catalytic activity than the Au/commercial α-Fe₂O₃ (Fluka) catalyst.     

AlO(OH)纳米片和纳米棒的水热法制备及其对牛血清白蛋白的吸附作用

以EDTA-2Na为螯合剂,铝盐为铝源,尿素为沉淀剂,采用水热法并使反应物以气液界面接触反应合成勃姆石型[AlO(OH)]纳米片及纳米棒;以透射电子显微镜(TEM)、X射线衍射仪(XRD)、傅里叶红外光谱仪(FTIR)等仪器对样品的尺寸、相位、形貌等进行了表征。结果表明,反应温度、时间等对样品的形貌、结晶度等起决定作用,合成的AlO(OH)对牛血清白蛋白(BSA)有较高的吸附能力,且在Al与BSA的质量比为1∶2时,吸附效果最佳。     

Novel chemical method for synthesis of LiV3O8 nanorods as cathode materials for lithium ion batteries

A novel method which is based on the hydrothermal reaction was employed to synthesize LiV₃O₈. First, the mixture solution of LiOH, V₂O₅, and NH₄OH was subjected to the hydrothermal reaction. The hydrothermal treatment yielded a clear, homogeneous solution. The evaporation of this solution led to the formation of a precursor gel. The gel was then heated at different temperatures in the range of 300-600 °C. The characterization by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) indicated that LiV₃O₈ nanorods have been obtained by this novel synthesis method. The electrochemical performance of the LiV₃O₈ nanorods have been investigated, which indicates that the highest discharge specific capacity of 302 mAh/g in the range of 1.8-4.0 V was obtained for the sample heated at 300 °C, and its capacity remained 278 mAh/g after 30 cycles.     

Hydrothermal synthesis of uniform Fe-doped Gd(OH)3 nanorods and their magnetic properties: Phase conversion from paramagnetism to ferromagnetism

High quality pure and Fe-doped Gd(OH)₃ nanorods were fabricated through a template-free hydrothermal method for the first time. Analysis of XRD indicates that Fe³⁺ was incorporating in the interstitial sites rather than occupying the substitutional sites, forming pure hexagonal structure of Gd(OH)₃ without any other impurity phase. TEM characterizations show that all the samples perform uniform rod-like morphologies with similar diameter and length, which suggests that the Fe doping has little influence on the morphologies of samples. ICP and XPS spectra suggest that the dopant Fe³⁺ is incorporated into the inner body sites, not on the surface of nanorods. Magnetic studies show that the magnetic phase can be converted from paramagnetism to room-temperature ferromagnetism by doping Fe³⁺ ions into the Gd(OH)₃ nanorods. The saturation magnetization (Ms) is sensitive to the amount of Fe dopants, and the Ms for Fe_0.03Gd_0.97(OH)₃ nanorods reaches the maximum value of 0.184 emu/g. It is considered that the ferromagnetic ordering is possibly originated from the exchange interaction of Fe³⁺ through the oxygen vacancies, leading to the formation of point defect-mediated bound magnetic polarons (BMPs). Ruling out the affect of morphologies and secondary magnetic phase on the magnetic properties, the ferromagnetic ordering in uniform Fe-doped Gd(OH)₃ nanorods, in which the dopant Fe³⁺ is incorporated into the inner body sites of nanorods, are of great importance to deeply understand the rare earth-based DMS/DMD systems and have potential applications in spintronic devices.     

Hydrothermal growth of ZnO nanostructures from nano-ZnO seeded in P(MMA-co-BA) matrix

Nano-ZnO synthesized by hydrothermal reaction were embedded in poly(methyl methacrylate-co-butyl acrylate) matrix (P(MMA-co-BA)) to produce the nano-ZnO/P(MMA-co-BA) nanocomposites via in-situ polymerization at 85 °C. The nano-ZnO/P(MMA-co-BA) nanocomposites were hydrothermal treated in the mixture solution of Zn(NO₃)₂·6H₂O and NH₄OH at 90 °C under various pH (i.e.7, 8, 9 and 10) and treatment time (i.e. 4, 6, 8, 10, 12 and 24 hrs). The nano-ZnO could act as seeding particles for hydrothermal growth of ZnO nanostructures on the surfaces of nanocomposites. The higher pH of basic solutions used in the hydrothermal treatment, the higher amount of Zn(OH)₄²⁻nuclei would be created, leading to a modification of the ZnO morphology from nano-nuclei to nanorods, nanorods bushes (flower-like nanostructure) and nanofibers with nanospine. The increase of hydrothermal treatment time resulted in the increases of amount and length of multidirectional grown ZnO nanorods. Data of the contact angle measurement exhibited the increase of hydrophobicity of the nano-ZnO/P(MMA-co-BA) nanocomposites after hydrothermal growth of ZnO nanostructures. The nanocomposites treated at pH = 10 for 24 hrs shows the highest hydrophobicity with the contact angle of 121˚. In addition, the thermal stability of the nano-ZnO/P(MMA-co-BA) could be improved by the formation of hydrothermal grown ZnO nanostructure on the nanocomposite surface.     

Hydrothermal fabrication and analysis of piezotronic-related properties of BiFeO3 nanorods

This paper reports the fabrication of vertically oriented BiFeO₃ (BFO) nanorods on indium tin oxide/glass substrates through hydrothermal synthesis. Further, their piezotronic, piezophototronic, and piezophotocatalytic properties were analyzed. Various synthesis parameters were examined to modulate the morphology and alignment of BFO nanorods, including the ratios of precursors, the pH values, types of complex agents, and reaction times and temperatures. Transmission electron microscopy results demonstrated single crystallinity of the BFO nanorods. A band gap of approximately 2.3?eV was determined. The piezotronic and piezophototronic properties were observed through facile current–voltage measurement. The extended application of piezophotocatalysis under alternating external stress and visible-light irradiation, to decompose methylene blue solutions, was also ascertained. The piezophotocatalytic efficiency was improved by approximately 30% over photocatalysis in the first 30?min. Both O₂^?□and□·OH radicals were crucial for these activities.     

水热合成技术的研究和应用──Ⅰ.钛酸盐晶体粉末的制备

应用水热合成法制备钛酸钡、钛酸锶、铁酸钙从钛酸铅晶体粉末，采用的技术路线分别以Ba（OH）2，Ca（OH）2，Sr（OH）2，Ph（OH）2及TiO（OH）2为水热合成钛酸盐的前驱物。研究了它们合成时的KOH浓度、温度和时间等影响因素。根据实验结果．按水热前驱物M（OH）2的特性分类．找出它们的共性和差异，提出了合成机理及MgTiO3和Al2（TiO3）3难以用水热合成的原因。     

NaY(WO4)2:Dy3+荧光粉的制备及其上转换发光性能

利用水热法合成了NaY(WO4)2:Dy3+上转换荧光粉. 通过XRD、SEM表征该荧光粉结构和形貌. 探讨了Dy3+浓度、pH值、反应温度及焙烧温度对NaY(WO4)2:Dy3+晶体结构、形貌及发光性能的影响,得到在Dy3+浓度为0.5%,pH=8,反应温度180℃,800℃焙烧条件下的样品具有最佳上转换发光性能. 利用776 nm近红外光激发NaY(WO4)2:Dy3+,观察到480 nm处的蓝光发射峰以及577 nm处的黄光发射峰. 其中蓝光来自Dy3+离子的4F9/2→6H15/2跃迁,黄光由Dy3+离子4F9/2→6H13/2跃迁产生.     

钨酸锌纳米棒的水热合成条件对其荧光及光催化性能的影响

以硝酸锌和钨酸钠为原料,采用前驱体一水热法制得了钨酸锌纳米棒.X射线衍射、透射电镜和扫描电镜等分析结果表明:所得产物为直径约20nm,长度约200nm的ZnWO4纳米棒.详细研究了水热温度和水热时间对纳米棒的形成、荧光发射强度以及对有机染料罗丹明B(maodamine B,RhB)光催化降解的影响.结果表明:水热温度为200℃,反应时间为16h得到的产品直径小,形貌均一,结晶度高且对RhB的光催化降解效率与商用光催化剂二氧化钛(P-25)接近.     

α-Cr2O3纳米棒的制备及其催化性能

以十六烷基三甲基溴化铵为表面活性剂(CTAB),乙酰丙酮铬为铬源,于180℃下用水热法合成了α-Cr2O3纳米棒.用TG-DSC及红外对中间体乙酰丙酮铬进行了表征.通过XRD衍射分析,表明产物Cr2O3为α相六方晶型结构.扫描电镜观察剑纳米棒的直径约为70～80nm,长度约为0.5～1.2μm.DTA数据表明,Cr2O3纳米棒对RDX的热分解具有催化作用.经退火处理的Cr2O3纳米棒能有效促进RDX的分解,使分解温度前移10 C.