Synthesis of Controlled Spherical Zinc Sulfide Particles by Precipitation from Homogeneous Solutions

Zinc sulfide (ZnS) powders have been obtained by precipitation from homogeneous solutions of various zinc salt compounds, with S^2- as precipitating anion, formed by decomposition of thioacetamide. Spherical particles with a very narrow size distribution can be obtained by controlling the synthesis parameters. The particle sizes are influenced by the nature of the associated anion. For example, nanometer-sized ZnS particles are formed using acetate or acetylacetonate anions under acidic pH conditions, controlled by the addition of acetic acid. Although the nucleation is accelerated by the use of acetic acid, limited particle growth occurs because of the formation of complexes with zinc cations that lowers the concentration of free cations in the solution. Also, the complexing-attachment phenomena of the ZnS particles with acetate and acetylacetonate anions lead to the arrest of particle growth processes. The presence of complexed Zn²⁺ species in the acidic solution is demonstrated both theoretically, using a model based on the calculations of the solubility isotherms of the soluble species, and by Fourier-transform infrared techniques. The nanostructured ZnS particles may provide a suitable semiconductor nanocluster material for optoelectronic applications as well as a phosphor suitable for application in flat-panel display technology.     

Preparation and Mechanism of Formation of Spherical Submicrometer Zinc Sulfide Powders

Spherical, submicrometer particles of zinc sulfide were homogeneously precipitated by thermal decomposition of thioacetamide in acidic aqueous solutions. The rate of sulfide ion generation, determined by various combinations of temperature, PH, and initial concentrations of zinc ions and of thioacetamide, as related to particle growth rate, had the paramount effect on the particle size distribution. Monosized, bimodal, or narrow size distribution powders were obtained under certain combinations of experimental variables. Particles were porous agglomerates of ∼13-nm sphalerite crystallites. Particle growth proceeded through diffusion-controlled aggregation of crystallites.     

Evolution of the Morphology of Zinc Oxide/Silica Particles Made by Spray Combustion

Pure and mixed ZnO–SiO₂ particles were made by flame-spray pyrolysis of zinc acetate and hexamethyldisiloxane or SiO₂ sol dispersed in methanol or water-in-oil emulsion, respectively. The product particles were characterized by nitrogen adsorption, infrared absorption, and X-ray diffraction. The evolution of solid or hollow particle formation along the flame axis was unraveled by transmission electron microscopy after collection by thermophoretic sampling. The effects of silicon precursor and solvent on product particle characteristics were evaluated. The characteristics of the product particles were controlled by the Si precursor and solvent.     

Fracture and Stiffness Characteristics of Particulate Composites of Diamond in Zinc Sulfide

Diamond particles have been embedded in hot-pressed zinc sulfide (ZnS) ceramic to improve various mechanical properties while preserving special optical properties. Roomtemperature mechanical tests on small specimens have shown that adding 10 wt% diamond to ZnS has no effect on the yield stress, but increases the tensile strength and the elastic moduli ∼20%, and increases the fracture toughness ∼100%. The doubling in fracture toughness can be explained by elastic interaction of the diamond particles with the crack-tip stress field. The results and the interpretation presented here are believed to represent a class of composite materials where both constituents are brittle but the dispersed phase has a much higher elastic modulus than the matrix.     

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。     

化学沉淀法合成甲基丙烯酸锌纳米晶粉体

以甲基丙烯酸、氢氧化钠、氯化锌、氨水等为主要原料,采用化学沉淀法在室温下合成了晶粒尺寸只有几十纳米的甲基丙烯酸锌粉体(ZMA);以FTIR,XRD,NMR,TEM等分析方法对粉体进行了表征,确认了产物的结构及其所属晶系;将合成产物与美国产SR-634甲基丙烯酸锌进行了性能比较,合成产物的平均粒径为40.6 nm,接近于后者的31.4 nm;讨论了氯化锌溶液的滴加速率、ZMA浓度、搅拌速率等因素对合成的甲基丙烯酸锌粉体粒径的影响;得到最优化实验条件为:氯化锌溶液的滴加速率0.5 mL/m in,ZMA浓度4.2 mol/L,搅拌速率100 r/m in,在此条件下,甲基丙烯酸锌收率达80.4%。     

通过测定硫化副产物硫化锌来检验硫化橡胶的硫化程度

介绍了用硫化副产物硫化锌来检验硫化橡胶硫化程度的方法。丙酮抽提过的硫化橡胶置于醋酸、盐酸和水的混合溶液中浸煮，使硫化胶中的硫化锌分解，产生的硫化氢气体用醋酸镉的缓冲溶液吸收，用碘量法测定其中的含硫量。结果表明，硫化胶中的硫化锌含量与硫化时间有关，并根据最佳硫化条件时的Ｓ（ＺｎＳ）含量，对所研究的硫化橡胶的硫化程度进行了检验。     

水热法和沉淀法从氧化锌矿制备纳米ZnO的研究

本文研究了从氧化锌矿制备纳米ZnO的方法及工艺条件,并利用XRD、SEM等方法分析表征样品.采用水热法处理模拟氧化锌矿浸出液制备了ZnO粉,随着碱含量的增加,氧化锌由长条状转变为短柱状,且有部分呈团簇状结合体存在.但是在处理实际浸出液时,由于硅酸根离子较氢氧根离子更易于与锌离子结合成为晶体生长基元,产物主要为硅酸锌.通过控制溶液的pH≈6,以及沉淀物的煅烧温度(500℃)和时间(6h),采用沉淀法获得了结晶性能良好的纳米ZnO颗粒.     

改性硫化锌在建筑涂料中的应用研究

制备了添加改性硫化锌颜料的内外墙乳胶漆,实验结果表明硫化锌颜料对涂料的储存稳定性影响小,对涂料的遮盖率有一定的贡献,同时涂料具有很好的抗菌防霉效果,是一种理想的建筑涂料功能添加剂。     

硫化锌微米球的合成及其光催化性能

以硫代乙酰胺为硫源,采用传统的水热法和改进的均匀沉淀–水热法制备了Zn S微米球。对制备的样品进行了表征;以紫外灯为光源,染料罗丹明B、甲基橙、亚甲基蓝为目标降解物,考察了两种方法制备的Zn S微米球的光催化活性。结果表明:改进的均匀沉淀–水热法条件温和,制备的Zn S微米球形貌规则、尺寸均一。沉淀–水热法制备的样品具有较高的光催化活性,在紫外光照射170 min后对罗丹明B的降解率达到98%;光照130 min后对甲基橙的降解率达到95%;光照110 min后,对亚甲基蓝的降解率达到98%。其光催化性能明显优于传统水热法制备的Zn S微米球。     

病毒灵水剂中碘化钾和硫酸锌的测定

采用沉淀滴定法和络合滴定法分别测定病毒灵水剂中的碘化钾和硫酸锌,其中碘化钾测定的标准偏差为0.011,变异系数为0.78,硫酸锌测定的标准偏差为0.006,变异系数为1.86。该分析方法快速、简单、准确。     

硫化锌性质、用途及制备方法概述

介绍了ZnS的结构、性质 ,重点介绍了ZnS的优异性能及其在各个领域的应用前景 ,并就目前制备ZnS的各种方法作了简单的介绍与评述。     

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     

锌冶炼渣浸出模拟液铁沉降试验研究

实验研究了不同反应条件的铁沉降效率及锌、镉损失率。结果表明,氧气做氧化剂pH为3.0~3.5时,反应7 h后,铁沉降效率不高,仅达到34%,锌、镉损失率随反应时间的增加而增加。铁沉降效率随pH及温度的升高而增大,SEM和XRD分析表明,pH为3.0时的沉铁渣中主要成分是针铁矿。     

Precipitation dynamics of zinc sulfide multiscale agglomerates

Homogeneous precipitation of zinc sulfide from thioacetamide decomposition in presence of zinc sulfate in acid solution results in the formation of four‐scale agglomerates. We present here experimental results relative to the monitoring of several physicochemical (pH, electrical conductivity, concentration in sulfide ions, turbidity) and morphological (agglomerate shape and size) parameters throughout the precipitation process. From these parameters essential characteristics of the precipitation process can be determined, especially the supersaturation level and the precipitated product mass. From this information and with the help of microphotographs of samples withdrawn at different stages of the precipitation, it is possible to formulate a new mechanism of zinc sulfide precipitation. In particular, the nature of the different agglomeration scales is elucidated as well their succession in time. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Effect of Diamond Dispersion on the Superplastic Rheology of Zinc Sulfide

The dispersion of diamond particles in superplastic zinc sulfide produces flow softening at low diamond concentrations, and hardening at high concentrations. The minimum in the flow stress is observed at 5 wt% (5.5 vol%) diamond content. The softening can be explained in terms of the grain refinement in the ZnS in the presence of diamond particles. The smaller grain size is shown to reduce the flow stress by enhancing the rate of diffusional creep. The hardening is believed to have been caused by the formation of a network among the diamond particles at high concentrations. The fact that the diamond particle size was approximately onethird the grain size of ZnS may have contributed to the network formation.     

Nanocrystallization and Phase Transformation in Monodispersed Ultrafine Zirconia Particles from Various Homogeneous Precipitation Methods

Monodispersed ultrafine (nano- to micrometer) zirconia precursor powders were synthesized by three different physicochemical methods: (I) forced hydrolysis, (II) homogeneous precipitation in inorganic salt solutions, and (III) hydrolysis/condensation of alkoxide. The forced hydrolysis method produced monoclinic nanocrystalline particles (cube shaped) of nanometer scale, which depended largely on the initial salt concentration. Methods II and III, both involving the use of alcohol as a solvent, exhibited a faster particle formation rate and generated amorphous ultrafine (submicrometer) monodispersed microspheres, indicating that the presence of alcohol may have stimulated particle nucleation due to its low dielectric property (and, thus, the low solubility of nucleus species in mixed water-alcohol solutions). Nucleation and growth of the particles in solutions are discussed based on the measurements obtained by small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS). High-temperature X-ray diffraction (HTXRD) and TGA/DTA studies elucidated the differences in phase transformation for different types of powders. The most interesting finding was the nonconventional monoclinic nanocrystal nucleation and growth that occurred prior to transformation to the tetragonal phase (at 1200°C) during the heat treatment of the nanocrystalline powders produced by the forced hydrolysis.     

反应沉淀法制备阿奇霉素药物超微粉体

利用反应沉淀法进行了阿奇霉素微粉化的实验研究,考察了NaOH溶液浓度、搅拌速度、搅拌时间和反应温度等因素对产品粒度、形貌、分散性及收率的影响. 分别采用扫描电镜(SEM)、比表面分析仪、X射线衍射仪(XRD)和红外光谱仪(FT-IR)对产品进行了分析与表征,并对微粉化产品和原料药进行了溶出性能研究. 实验结果表明,利用此方法可以制备得到平均粒径约为413 nm的无定型阿奇霉素超微粉体,与原料药相比,微粉化的阿奇霉素粉体比表面积增加了约27倍,相应地,药物的溶出性能较原料药明显改善.     

Grain Growth in Superplastically Deformed Zinc Sulfide/Diamond Composites

Grain growth in superplastically deformed ZnS/diamond composites was much greater than in undeformed specimens exposed to the same time and temperature. The extent of grain growth depended on the volume fraction of diamond particles. Grain growth was suppressed by the addition of 10 wt% diamond particles in superplastically deformed specimens. In static annealing, however, only 1 wt% diamond particles were enough to supress grain growth, which is a factor of 10 smaller than estimated by the Zener condition.     

铜锌锡硫半导体薄膜材料的制备与表征

采用水热法成功制备了Cu2ZnSnS4(CZTS)半导体材料,通过浸涂法制备了相应的薄膜,并在N2气氛中于400℃对薄膜进行了退火处理.用X射线荧光光谱分析了所得CZTS粉末中各组成元素的含量,并分别用X射线衍射、扫描电子显微镜和紫外-可见-近红外光谱对CZTS薄膜样品的晶体结构、表面形貌和带隙进行了表征.结果表明:所...