不同沉淀剂制备氧化铈抛光粉

氧化铈(CeO₂)抛光粉在光学玻璃、手机盖板、集成电路等领域内有着广泛的应用。合成高端CeO₂抛光粉主要采用液相沉淀得到前驱体,再经过煅烧转型制得CeO₂。前驱体是决定CeO₂抛光粉性质和性能的关键因素之一。通过模拟工业上常用的制备方法,以氯化铈(CeCl₃)为铈源,使用碳酸钠(Na₂CO₃)、碳酸铵[(NH₄)₂CO₃]、碳酸氢铵(NH₄HCO₃)、二水合草酸(H₂C2O₄·2H₂O)和氢氧化钠(NaOH)为沉淀剂,合成了一系列CeO₂抛光粉的前驱体。利用X-射线衍射仪(XRD)、扫描电子显微镜(SEM)、激光粒度仪等手段表征了前驱体的晶相、形貌、粒度等性质,并研究了前驱体煅烧转型后的CeO₂性质及其对K9光学玻璃的...     

Preparation of Fine Spherical Particle Sized Ceria by Precipitation Method with Ammonium Bicarbonate

Fine spherical panicle sized ceria (CeO2) was prepared by homogeneous precipitation method with ammonium bicarbonate as precipitant. The prepared CeO2 has the primary panicle size of 10-50nm when calcined between 400-700℃ analyzed by XRD and the aggregated particle size is about 300 nm measured by LASER panicle sizer. SEM, TGDTA and Zeta-potential analyzer were employed individually to study the morphology, and the fonnation of CeO2 product. It was found that excess NH4NO3 can serve as an sphericallization agent to prepare spherical Ce02 powder by precipitation method.     

球形MnCO3粉的制备及其粒径控制

以MnSO4为锰源,NH4 HCO3为沉淀剂,六偏磷酸钠(SHMP)为分散剂,采用液相沉淀法制备出了粒径均一的球形MnCO3粉.考察了反应温度、反应物浓度比、SHMP用量比等因素对MnCO3粉粒径的影响,并利用激光粒度分析仪、扫描电镜和X射线衍射对实验结果进行了表征.研究结果表明,在10～50℃范围内,MnCO3粉的粒...     

Synthesis and Luminescent Properties of Superfine Sr2CeO4 Phosphors by Sol-Gel Auto- Combustion Method

Citric acid complexing sol-gel auto-combustion method was explored to synthesize superfine Sr2CeO4 phosphors using the inorganic salts Sr（NO3）2 and Ce（NO3）3 as raw materials together with citric acid （CA） as a chelating agent. TGDTA, XRD, SEM and photoluminescence spectra were used to investigate the formation process, microstructure and luminescent properties of the synthesized Sr2CeO4. The results show that the crystallization of Sr2CeO4 begins at about 800 ℃ and completes around 900 ℃ with an orthorhombic structure. When the calcination temperature is above 1000 ℃, Sr2CeO4 partly decomposes into SrCeO3. SEM studies show that the particles of Sr2CeO4 obtained at 900 ℃ are sphericallike shape and superfine with diameter below 100 nm. The excitation spectrum of the superfine Sr2CeO4 phosphors displays a broad band with two peaks around 290 and 350 nm respectively. The former peak is stronger than the latter one. This broad band is due to the charge transfer （CT） band of the Ce^4＋ ion. Excited by a radiation of 290 nm, the superfine phosphors emit a strong blue-white fluorescence, and the emission spectrum shows a broad band with a peak around 470 nm, which can be assigned to the f→t1g transition of Ce^4＋ . It is found that the emission intensity is affected by the calcination temperature.     

热镀锌渣的利用

以硫酸浸出热镀锌渣获得硫酸锌溶液和饱和碳酸氢铵溶液为原料,用直接沉淀法制备出了平均粒径20 nm左右的纳米氧化锌。制备过程中对影响前驱体和纳米氧化锌的粒度的一些因素进行了实验研究。结果表明:在反应温度55℃,饱和碳酸氢铵的加入速度4 mL/min,沉淀终点pH=7.0的条件下,从锌浓度为100 g/L的ZnSO4溶液中可以获得平均粒径1.6μm的碱式碳酸锌前驱体。在600℃,焙解60min的条件下可获得粒径20 nm左右的纳米氧化锌。     

Formation Process of Crystalline Ammonium Yttrium Carbonate Double Salt

The research was mainly based on the formation condition of crystalline ammoniu yttrium carbonate and the variationcharacteristics of PH value duringthe crystallization in whichNH4HCO3 was used to precipitateyttrium ion. It is found that thecrystallization process is alwaysassociated with the descent of pH.The pH of solution is controlled bythe crystallization reaction of ammonium yttrium carbonate and thehydrolysis of NH4HCO3. Based onthe pH variation, it can be judgedwhether the crysta…     

微波-超声波联合辅助下活性氧化锌的制备与表征

以NH3-NH4HCO3-H2O体系中所得锌氨溶液为原料,在微波与超声波辅助及常规加热下运用蒸氨法制备活性氧化锌前驱体,考察了锌溶液浓度和蒸发温度对前驱体粒度的影响,对前驱体表征结果表明：采用微波-超声波联合辐射法制备出产物的粒度和形貌更易于控制,对制备出活性氧化锌粉体进行了SEM、X衍射及纯度分析表征,结果表明微波及超声波的加入有利于获得均匀分散、平均粒径为2.3μm,纯度可达98%以上的活性氧化锌产品.     

Preparation and characterization of Y3Al5O12:Ln（Ln=Eu,Ce） phosphor powders by ultrasonic atomization and co-precipitation process

A novel technique for YAG:Ln(Ln=Eu,Ce) phosphor powder synthesis with a nanocrystalline structure was developed.Nanocrystalline YAG:Ln powder was prepared by an ultrasonic atomization and co-precipitation method using a mixture solution of ammonium hydroxide(NH3·H2O) and ammonium hydrogen carbonate(NH4HCO3) as precipitant.The as-prepared nano-powders were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and fluorescence spectrometer.The obtained phosphor powders were homogenous and in size of 50-70 nm.The results demonstrated that by using ultrasonic atomization and co-precipitation process,we could synthesize a good quality YAG:Ln(Ln=Eu,Ce) phosphor powder that had many potential applications.     

Preparation and characterization of nano-rare earth composite materials:application in selectivity catalytic oxidation of ammonia and its cytotoxicity study

The manufacture,physical characterization,environmental applications and cytotoxicity properties of nanocomposites consisting of CuO/CeO2 nano-rare earth composite materials prepared using the coprecipitation method at molar ratio of 6:4 with aqueous solutions of copper nitrate and cerium nitrate were reported.The performance of the selective catalytic oxidation of ammonia to N2(NH3-SCO) over a CuO/CeO2 nano-rare earth composite materials in a tubular fixed-bed reactor(TFBR) at temperatures from 423 to 673 K in the presence of oxygen was elucidated.The catalytic redox behavior was determined by cyclic voltammetry(CV).The nanocomposite particles were characterized by TEM,with a tiny particle size around 10 nm with high dispersion phenomena.Further,cell cytotoxicity and the percentage cell survival were determined by using 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethoxyphenol)-2-(4-sulfophenyl)-2H-tetra-zolium(MTS) assay on human lung MRC-5 cell line.Experimental results showed that no apparent cytotoxicity was observed when the MRC-5 was exposed to the CuO/CeO2 nanocomposite materials.     

掺钕氧化钪激光透明陶瓷纳米粉体的合成及研究

研究了化学共沉淀法合成Nd:Sc2O3纳米粉的工艺.以Sc2O3为基质材料,掺杂0.5％(原子分数)的Nd3+,添加适量聚乙二醇(PEG)和(NH4)2SO,作为分散剂,以氨水(NH3·H2O)和碳酸氢铵(NH4HCO3)混合溶液作复合沉淀剂,采用化学共沉淀法获得了碱式稀土碳酸盐前躯体,在1100℃下煅烧该前躯体4h,制备出性能良好的Nd:Sc2O3纳米粉.采用热重-差热分析仪(TG/DSC)、红外光谱分析仪(IR)、X射线衍射仪(XRD)、透射电子显微镜(TEM)等测试手段对Nd:Sc2O3前躯体和煅烧后的粉体进行表征.实验结果表明:在室温下,用氨水和碳酸氧铵混合溶液作为复合沉淀剂合成出的前躯体为碱式稀土碳酸盐.通过XRD和EDS能谱分析,Nd3+完全固溶于Sc2O3的立方晶格中,这将有利于制备激光透明陶瓷.在1100℃的温度下煅烧此前躯体得到的Nd:Sc2O3纳米粉具有颗粒粒度小(约50 nm)、分散性好、团聚程度轻、结晶良好的性能.因此,采用此工艺合成的粉体将有可能制备出的Nd:Sc2O3透明陶瓷.     

环保药剂浸出多金属硫金矿及伴生元素在浸出过程的行为

目前,我国开发的替代氰化钠的新型低毒药剂主要用于氧化型低品位金矿石的处理,未见有相关用于多金属硫金矿浸出的报道。以多金属硫金矿为研究对象,主要考察了助浸剂量、矿浆浓度、药剂用量、球磨时间、浸出时间以及Na2CO3/NH4HCO3配比对其中金、银及伴生金属元素浸出效果的影响。在环保药剂加入量50 kg/t、矿浆浓度40%、Na2CO3和NH4HCO3质量6 kg/t（质量比1︰1）、室温下浸出12 h,金和银浸出率高达97.71%和67.49%,与氰化法相当,铜和铅的浸出率小于20%,基本留在浸出渣中,但锑的浸出率高达90%左右,因此应适当控制原料中锑含量。用环保药剂浸出多金属硫金矿,不需改变原有的氰化工艺流程和设备,但药剂耗量较大。因此,降低药剂消耗是未来的重点研究方向。     

共沉淀法制备稀土石榴石Ln3Al5O12(Ln=Y, Ce, Yb)

以Y2O3、Yb2O3、Al(NO3)3.9H2O和Ce(NO3)3.6H2O为原料,NH4HCO3、NH3.H2O做复合沉淀剂,用共沉淀法制备纳米稀土石榴石Ln3Al5O12(LnAG,Ln=Y,Ce,Yb)粉体。用TG/DTA、XRD、SEM、TEM等手段对LnAG前驱体及煅烧后的粉体进行表征。结果表明,用上述方法在1 000℃煅烧3h可得到分散性好、形状规则且粒径为50nm左右的Y3Al5O12、Yb3Al5O12、Y2.9Ce0.1Al5O12石榴石粉体,但不能得到Ce3Al5O12石榴石,合成石榴石粉体的最佳煅烧温度为1 050℃以上。     

Preparation of High-Surface Area Nano-CeO2 by Template-Assisted Precipitation Method

The high-surface area nano-CeO2 was prepared by Ce（NO3）3 by precipitation method, with surfactant cetyhrimethyl ammonium bromide （CTAB） as templating agent. The effects of the precipitating agents, reaction temperature, ageing time, and calcination temperature on the surface area, as well as the pore structure and the mean crystallite size of nano-CeO2 were studied. It was found that the reaction of Ce（NO3）3 with NaOH in the presence of CTAB at 90℃ for 12 h yieldsed a cerium oxide/surfaetant mixture, which after calcination at 400℃ resulted in high-surface area nano-CeO2. The mean crystallite size of CeO2 was approximately 6 nm, surface area was in excess of 200 m^2· g ^- 1, pore size was approximately 9 nm, and the pore distribution was concentrative. Moreover, the surface area can still reach 147 m^2·g^- 1 after calcination at 700 ℃, which showed the good thermal stability of the CeO2. The number of oxygen vacancies in the structure of CeO2 corresponded with the surface area of CeO2, and the high surface area was propitious to the formalion of oxygen vacancies.     

撞击流-活性炭吸附法制备氧化钇超细粉体

以Y( NO3)3·6H2O和碳酸氢铵为原料,在撞击流反应器中制备碳酸钇,经焙烧得到超细氧化钇粉体.考察了分散剂加入量、反应物摩尔比n( NH4HCO3)/n(Y(NO3)3)、活性碳用量、反应温度、反应时间、搅拌速度以及碳酸钇的焙烧温度和焙烧时间等因素对Y2O3粒径的影响,并用WJL激光粒度仪、TG、XRD和SEM等表征手段对产品进行表征,从而获得制备超细氧化钇的优化工艺条件为:PEG4000的质量为硝酸钇的3％,活性炭用量为0.025 mol·L-1,反应物摩尔比n( NH4HCO3):n(Y( NO3)3)为8:1,反应温度50℃,反应40 min,螺旋桨转速1000 r·min-1,800℃下焙烧1.5h,在此条件下制得球形氧化钇超细粉体,表观粒径小于0.5μm.     

Effect of Surface Modification on Behaviors of Cerium Oxide Nanopowders

Study was made on the effect of surface modification on the behaviors of cerium oxide nanopowders.A surfactant-sodium dodecyl sulfate（C12H25SO4Na）was used to modify the surface of CeO2 powder particles.The unmodified and modified CeO2 powders were characterized by using a powder comprehensive characteristic tester,laser particle size analyzer,specific surface area tester,X-ray diffraction tester,and a scanning electron microscope.The testing and analysis results showed that C12H25SO4Na surface modification might increase the flowability and dispersity,and decrease the specific surface area and agglomeration of CeO2 powders.The mechanism of the surface modification of CeO2 powder particles was also discussed.     

含氟铈基稀土抛光粉的制备及其抛光性能

以碳酸镧铈为前驱体,采用氢氟酸氟化、高温焙烧、机械搅拌磨的方法制备中位粒径较小的含氟铈基稀土抛光粉。结果表明,所得产物中固溶体具有立方萤石结构;随着氟掺杂量的增加,开始析出四方结构的LaOF相,CeO2的XRD特征峰向右偏移,结晶度提高,粉体的振实密度随之增大;对光学玻璃的抛光能力在氟掺杂量为6%时出现极大值,被抛光物体的表面光洁度随氟掺杂量的增大而下降。     

Preparation and Characterization of Nanocrystalline CeO2 by Precipitation Method

CeO2 nanocrystalline particulates with different sizes were prepared by precipitation method using ethanol as dispersive and protective reagent. XRD spectra show that the synthesized CeO2 has cubic crystalline structure of space group OH^H-FM3M, when calcination temperature is in the range of 250 - 800 ℃. TEM images reveal that CeO2 particles are spherical in shape. The average size of the particles increases with the increase of calcination temperature. Thermogravimetric analysis indicates that the weight loss of precursor mainly depends on the calcination temperature, and little depends on the calcination time. Measurements of CeO2 relative density show that the relative density of CeO2 nanocrystalline powders increases with increasing CeO2 particle size.     

微乳液法制备纳米二硫化钼酸沉过程研究

以钼酸钠为钼源,草酸为还原剂,硫化钠为硫源,对微乳液法制备纳米二硫化钼工艺中的酸沉过程进行研究。主要考察酸沉方式、微乳液体系、加酸量及体系含水量对制备的二硫化钼粉末粒度及收率的影响。结果表明:采用TritonX100/异戊醇/正庚烷/H2O微乳液体系,加酸量为钼酸钠摩尔量的1.25倍,控制体系中水与表面活性剂的摩尔比为25,可得到分散性较好、尺寸均匀、平均粒径60 nm的球形二硫化钼粉末。     

AACH在柠檬酸铝制备多孔氧化铝中的应用研究

针对从简单铝盐(AlCl3,Al(NO3)3等)体系中制备化学品氧化铝易发生凝聚而导致颗粒分散性差的问题,提出利用柠檬酸作为铝的络合剂,并采用碳酸铝铵(AACH)作为中间体制备多孔氧化铝的方法.将柠檬酸铝溶液调节到一定pH值后,滴加到碳酸氢铵溶液中可以得到结晶良好的AACH固体,再通过简单焙烧后即可得高比表面积的多孔球型Al2O3产品.通过对原料碳酸氢铵和柠檬酸铝的物质的量之比β、反应体系pH值、反应温度及陈化时间对铝转化率α的影响的研究发现,在β=2,pH =9,室温25℃,陈化8d,有50％的柠檬酸铝转化为AACH.同时推测出,由于AACH的形成受柠檬酸,铝酸钠,碳酸氧铵三重络合-缓冲体系的限制,首先需要调节柠檬酸铝,其pH值大于9后缓慢释放出Al(OH)4-,Al(OH)4-再同碳酸氢铵反应易得到结晶良好的AACH晶体.TG-DTA热分析和XRD测试表明:300℃下AACH可完全分解为不定型氧化铝,700和1400℃下焙烧可分别得到γ-Al2O3,α-Al2O3.SEM和TEM测试表明,所得AACH粒径约为15 μm,并由大量长度为500 nm左右的纳米棒组成,700℃焙烧后得到形貌不变,含有大量孔径为1～5nm微孔、BET比表面积为235 m2·g -1的多孔氧化铝.     

CeO2催化强化高炉喷吹煤粉燃烧机制

为了研究稀土氧化物CeO2对高炉喷吹煤粉的助燃机制,以某炼铁厂高炉喷吹煤粉为原料,利用煤粉燃烧炉进行煤粉燃烧试验并收集未燃煤粉,通过热重-差热法分析CeO2对喷吹煤粉的助燃机制,结合XRD和SEM检测分析未燃煤粉.结果表明:助燃剂CeO2对喷吹煤粉的助燃效果显著,其添加比例控制在1.5％(质量分数)左右比较适宜;CeO2在煤粉固定碳表面上形成络合盐Ce4+(CO-)4,减弱了两相反应物间的势能垒,促使挥发分的开始燃烧放热温度降低,固定碳燃烧温度区间变窄;随着CeO2的加入,Ce4+ (CO)4成倍增长,在XRD图谱中表现为未燃煤粉的微晶尺寸逐渐增大;在CeO2的作用下未燃煤粉颗粒的平均粒径与原煤未燃煤粉颗粒的平均粒径相比减小了3.48 μm,表面出现大量孔洞结构.