液相沉淀法制备纳米硫化锌的研究

介绍了利用液相沉淀法制备纳米硫化锌的方法。其过程是以硫酸锌和硫化铵为原料，加入表面活性剂1631，经过沉淀、过滤、洗涤、干燥，最后得到产品。对其进行比表面积、孔容积和透射电镜（TEM）测定，结果表明：制备的硫化锌晶粒尺寸在5—30nm，并最终确定了最佳的原料配比，即硫酸锌与硫化铵物质的量比为1：（1-0．8）。     

纳米硫化锌的制备及其研究进展

纳米硫化锌具有许多特异的光电性能 ,对其制备方法的研究越来越引起人们的重视。详细介绍了制备纳米硫化锌颗粒的固相法、液相法、气相法等不同方法并比较了它们的优缺点 ,结合纳米硫化锌材料的实际应用选用不同的制备方法 ,必将进一步推动纳米硫化锌的开发研究     

用特殊液相沉淀法制备纳米碳酸锶

根据反应胶粒析出机理及实验原理,采用快速高强度机械混合沉淀法,并控制溶液最终pH≥10,让沉淀爆发性快速生成,然后用NH4OH、NH4HCO3清洗液过滤,洗涤,制备了碳酸锶纳米粉体,经TEM和XRD表征,获得的碳酸锶纳米粉体平均粒径为29．3nm,分散性良好,晶型为斜方晶系。     

纳米硫化锌的制备与应用研究现状

介绍了纳米硫化锌的制备方法,固相法、液相法、气相法,纳米硫化锌性能优越,用途广泛.     

利用热处理方法制备纳米硫化锌晶体

通过液相沉淀法制备出无定形硫化锌粉末,硫化锌粉末经高温热处理后制得纳米硫化锌粉状晶体。具体过程为:将硫化钠溶液缓慢加入酸性的氯化锌溶液中,沉淀、洗涤、干燥后,研磨至200目以上,并在H_2气氛保护下于400℃温度焙烧,制得20～30nm粒径的硫化锌晶体。     

纳米硫化锌的制备及应用研究新进展

综述了近年来纳米硫化锌的制备方法,对固相法、液相法和气相法等不同制备工艺的优劣进行了比较,并详细地介绍了纳米硫化锌的性能及其在各种领域中的应用。     

均匀沉淀法制备不同粒径的纳米硫化锌

以硫代硫酸钠为硫源,采用均匀沉淀法研究了不同粒径纳米硫化锌的制备,讨论了反应温度、加热方式、反应物的浓度及物质的量比对其粒径的影响。研究结果表明：通过控制制备工艺条件,采用均匀沉淀法可以制备出平均粒径为4～24 nm、立方晶型的球形纳米硫化锌;制备工艺条件对纳米硫化锌的平均粒径有显著影响;加热方式对硫化锌的平均粒径影响较大,微波加热比水浴加热制备的硫化锌粒径小;此外,纳米硫化锌的粒径随着反应温度的增加、反应物浓度的增加、醋酸锌和硫代硫酸钠物质的量比的减小而减小。     

液相沉淀法制备纳米粒子的过程特征和原理

以制备纳米粒子为目的的液相沉淀过程 ,其成核、生长、聚结和老化等 ,均具有自身特征和规律。理想的沉淀过程是成核和生长分区或分期进行 ,在成核区或成核期 ,体系过饱和度高于均相成核临界过饱和度 ,为均相成核动力学所控制 ;在生长区或生长期 ,体系过饱和度小于成核临界过饱和度 ,为界面生长机理所控制。提出采用特征成核时间和特征扩散时间 ,判定反应沉淀过程的成核控制因素。提出粒度分布控制的技术关键 ,是将成核过程由微观混合控制转化为动力学控制     

油溶性硫化锌纳米微粒的制备及抗磨性能评价

通过共沉淀法制备出Py DDP-18表面修饰的硫化锌纳米微粒。采用元素分析、红外光谱、透射电子显微镜对产物组成和结构进行表征,并考察了其在有机溶剂中的分散性。结果表明:所得表面修饰Zn S纳米微粒尺寸大约在50 nm,其在氯仿、丙酮和基础油中具有良好的分散性。利用四球极压抗磨试验考察了其摩擦学性能,磨损试验结果表明表面修饰的Zn S纳米微粒具有良好的抗磨、减摩性能。     

纳米Cu2O的特殊液相沉淀法制备及其光催化活性

采用高强度机械混合的特殊液相沉淀法制备了纳米Cu2O粉体,通过TEM和XRD对其进行表征。用它做催化剂在日光作用下对酸性品红溶液进行了光催化降解实验,研究了葡萄糖添加浓度、酸性品红溶液的初始浓度和催化剂的重复使用对光催化性能的影响。结果表明分散剂葡萄糖浓度为7g/L时制得的纳米Cu2O光催化活性最佳,当酸性品红溶液的初始浓度为6 mg/L时,2.5 h降解率高达99.1%,重复使用6次后其降解率仍可达到75%。     

化学沉淀法制备纳米SiO2颗粒

二氧化硅以其优越的耐热隔热性能引起各个行业的广泛关注。以硅酸钠为硅源、氯化铵为沉淀剂、十六烷基三甲基溴化铵（CTAB）为分散剂,采用化学沉淀法合成二氧化硅纳米颗粒。采用TG-DSC测试分散剂CTAB的分解温度,并用傅里叶红外光谱、X射线以及扫描电镜对制备的二氧化硅粉末进行表征。结果表明,此方法制备的二氧化硅颗粒为无定形态纳米颗粒,平均粒径为80 nm。     

Synthesis of tungsten oxide nanoparticles by acid precipitation method

Tungsten oxide (WO₃) nanoparticle having average size of 30 nm, and nanoplate having average dimension of 190 ± 15 nm wide and 50 ± 5 nm thick were prepared by controlling a precipitation of ammonium tungstate para pentahydrate with nitric acid. The two nanostructured microstructures were obtained by varying the stirring time during the precipitation reaction while the other synthesis parameters were identical. Phase transition of the WO₃ precipitate was investigated by means of thermal analysis and X-ray diffraction, while the microstructure was observed by using a scanning electron microscope and a transmission electron microscope. The effect of the concentrations of the tungstate salt and nitric acid on the rate of precipitation and the percent yield of the precipitating product is also described.     

超重力液相沉淀法制备纳米铁酸钴

针对磁力搅拌器制备纳米材料时存在粒径分布宽、分散不均匀的问题,采用撞击流-旋转填料床结合化学共沉淀法,以Fe（NO₃）₃·9H₂O、Co（NO₃）₂·6H₂O、NaOH为原料制备CoFe₂O₄纳米颗粒。研究了转速、液体流量、NaOH浓度以及晶化时间对CoFe₂O₄纳米颗粒粒径的影响;并与磁力搅拌器制备的CoFe₂O₄纳米颗粒在磁性能方面进行了对比。采用X射线衍射仪（XRD）、傅里叶红外光谱仪（FTIR）、透射电镜（TEM）、纳米粒度仪及振动样品磁强计（VSM）对产物的粒径形貌及磁性能进行表征。结果表明：CoFe₂O₄纳米颗粒的粒径随转速、液体流量和NaOH浓度的增加而减小,但随晶化时间的增加而增大。最佳工艺条件为：转速900r/min,液体流量60L/h,NaOH浓度3mol/L,晶化时间6h。此条件下制备的CoFe₂O₄纳米颗粒的粒径约为20nm,饱和磁化强度为75.43emu/g,较磁力搅拌器提高40%。     

配合-均相沉淀法制备纳米掺锑氧化锡

以五水氯化锡和三氯化锑为原料,柠檬酸为配合剂,尿素为均相沉淀剂,采用配合-均相沉淀法制备纳米掺锑氧化锡粉体(ATO).采用差热分析、红外分析、X射线衍射、透射电镜测试、比表面积测定对制得的粉体进行表征.结果表明,合成的纳米ATO具有四方金红石结构,粉体结晶完整.通过XRD计算得粉体的平均粒径为9.8 nm;透射电镜测定结果表明粉体的分散性较好,粒径大约为12 nm;比表面积测定粉体的比表面积达到65.2 m2/g.采用配合与均相沉淀法相结合的方法可以制备出粒径小、比表面积大和分散性好的纳米掺锑氧化锡粉体.     

Synthesis of hydroxyapatite nanoparticles in ultrasonic precipitation

Nanocrystalline hydroxyapatite (HAp) was prepared by a precipitation method with aid of ultrasonic irradiation using Ca(NO₃)₂ and NH₄H₂PO₄ as source material and carbamide (NH₂CONH₂) as precipitator. The crystallization and morphology of the prepared nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanism and kinetics of the nano-hydroxyapatite were considered in particular, and the influence of the temperature and time on the HAp formation rate was also investigated. The results show that the needle-like HAp crystalline was prepared by the ultrasonic precipitation process. The HAp content increases with the preparation temperature and time. The adding of carbamide is helpful for formation of HAp nanoparticles. An Arrhenius relationship was found between the HAp formation rate and the temperature, and an apparent activation energy of 59.9 kJ/mol was obtained by calculation.     

Synthesis of barium fluoride nanoparticles by precipitation in ethanol-aqueous mixed solvents

In this work, the BaF₂ nanopowders with different particle size were synthesized by precipitation in the ethanol/water mixed solvents. Five kinds of compositions of mixed solvents, including pure water, 25 vol.%, 50 vol.%, 67.5 vol.%, and 75 vol.% of ethanol were used. The effects of aging and the volume percentage of ethanol in the mixed solvents on the resultant BaF₂ nanoparticles were under investigation. The size and morphology of the BaF₂ particles were characterized by TEM, FSEM and XRD analyses. The results show that after aging for 2 h the particle size of the BaF₂ precipitates in the 50% mixed suspension changes little. The prepared BaF₂ particles all exhibit cubic fluorite structures no matter what kind of composition is used. In pure water environment, the size of BaF₂ particles is about 70 nm, whereas it reduces to 33 nm in the 75% mixed solution. As the vol.% of ethanol increases the particle size decreases, and other properties such as the size distribution, dispersion, oriented growth et al. are also modulated. These alterations can be interpreted by varying the dielectric constant of mixed solvent.     

Synthesis and optical characterization of ZnS,ZnS:Mn and (ZnS:Mn)_CdS core–shell nanoparticles

ZnS and ZnS:Mn nanoparticles and (ZnS:Mn)_CdS core–shell nanoparticles were synthesized by a chemical precipitation method, this method is simpler than previously reported methods for the same sort of nanoparticles. The nanoparticles obtained were characterized by XRD and spectroscopy techniques (fluorescence and UV–vis absorption). The core–shell nanoparticles present an improved fluorescence signal over ZnS and ZnS:Mn nanoparticles at 580 nm.     

Optical properties of ZnS nanoparticles produced by mechanochemical method

Nanosized zinc sulfide (ZnS) has been synthesized by the mechanochemical route using zinc acetate and sodium sulfide as source materials in a high energy planetary ball mill (HEPBM) with 300 rpm for 2 h. The mechanochemically synthesized powders have been analyzed by X-ray diffraction (XRD) for phase analysis, Field Emission Scanning Electron Microscope (FESEM) for the morphological characterization, UV–vis–NIR spectrophotometer for determining band gap energy and Fluorescence spectroscopy for determining the emission wavelength. The crystallite size of the synthesized ZnS nanoparticles calculated by the Debye–Scherer's formula is in the range 7–9 nm. FESEM morphology shows the fibrous structure of ZnS samples. The value of optical band gap has been found to be in the range 5.2–5.3 eV. Room temperature photoluminescence (PL) spectrum of the samples exhibits a blue light emission using UV excitation wavelength of 280 nm.