胶束辅助的共沉淀法制备YAG：Eu纳米粉体及其发光性能

以CTAB为表面活性剂,乙醇、正丁醇为CTAB的增溶剂,采用胶束辅助的共沉淀法制备了YAG：Eu前驱体。在空气气氛中,分别在900℃、1000℃下烧结2h得到YAG：Eu粉体。应用XRD、TEM和光致发光等方法对试样进行了表征。结果表明：在900℃、1000℃烧结前驱体可合成立方相YAG：Eu;YAG：Eu颗粒大小在50～70nm之间,团聚成珊瑚虫形;YAG：Eu粉体发射橙红色光。     

高能球磨对YAG陶瓷制备的影响(英文)

通过高能球磨法处理Y2O3-Al2O3(yttrium aluminum garnet,YAG)混合粉体,对球磨产物进行煅烧、成型以及烧结,并对固相反应中的物相变化、YAG粉体形貌以及YAG陶瓷密度、力学性能及显微结构进行表征和分析,确定了最佳的球磨时间和粉体煅烧温度.研究表明:经过40h高能球磨,得到的球磨产物具有良好的活性.采用传统固相法制备的YAG粉体,需要在1 500℃煅烧,该方法处理的YAG粉体在1 200℃煅烧2 h,可以得到活性较高的YAG粉体,使粉体的煅烧温度下降了300℃.利用常压烧结在1 550℃烧结坯体2h,得到致密的YAG陶瓷,明显改善了YAG陶瓷制备技术.     

碳酸盐共沉淀法制备掺镱钇铝石榴石透明陶瓷的工艺

以质量分数为99．999％的Yb2O3,Y2O3和Al2O3为原料,碳酸氢铵作为共沉淀剂,采用碳酸盐共沉淀法在1200℃制备出掺镱钇铝石榴石(Yb：YAG)陶瓷超细粉体。1700℃真空烧结后得到透光度良好的Yb：YAG多晶陶瓷。对Yb：YAG粉体样品进行X射线衍射分析、热重-差热分析和扫描电镜分析。结果表明：所合成的YAG超细粉仍为立方晶系晶体结构,晶格常数为a=12．01A。Yb：YAG粉体样品颗粒度小、粒径均匀、流动性好,粒径在100～150nm之间。对烧结后的Yb：YAG陶瓷样品进行的形貌和红外光谱分析表明：陶瓷断面气孔率低,多晶晶粒尺寸在1～2μm之间。     

钇铝石榴石激光透明陶瓷纳米粉体的研究

本试验以硝酸钇、硝酸铝和硝酸钕为原料,碳酸氢铵为沉淀剂,聚乙二醇（PEG400）及硫酸铵为分散剂,采用共沉淀方法制备了Nd：Y3Al5O12（Nd：YAG）,研究了分散剂的种类及盐溶液初始溶度对粉体性能的影响。并采用X射线衍射仪、扫描电镜等对YAG粉体进行了表征分析。实验结果表明,合成的YAG粉体均为立方晶系石榴石型结构。当以PEG为分散剂时,所得粉体颗粒度小、分散均匀、粒径在50nm左右,且随着盐溶液初始浓度的增加,YAG颗粒粒径减小。     

丙二酸溶胶-凝胶法合成亚微米级YAG:Ce,Gd黄色荧光粉

以丙二酸为络合剂,通过溶胶-凝胶法合成了亚微米级YAG:Ce,Gd黄色荧光粉.采用TG/DSC、XRD研究干凝胶热分解和YAG晶相形成的过程;通过荧光光谱分析了Gd~(3+)的掺杂对荧光粉的发光强度的影响规律;通过SEM观察粉体的微观形貌.结果表明:经1200 ℃煅烧3 h得到的荧光粉,粉体粒径为0.3～1 μm,颗粒规则接近球形;随着Gd~(3+)掺杂量的增加,荧光粉的发射光谱由525 nm红移到550 nm.     

溶胶-凝胶法制备Y3Al5O12粉体的研究

本文以Y2O3、硝酸铝以及柠檬酸为起始原料，采用溶胶一凝胶法合成了YAG粉体，研究了烧成温度及烧成时间对YAG粉体形成的影响，并利用SEM和XRD等实验技术对粉体进行了表征。结果表明，用溶胶一凝胶法成功地合成了纳米YAG粉体(50～70nm)，且随着烧结温度的升高和烧结时间的延长，颗粒尺寸不断增大。     

共沉淀法合成YAG：Ce纳米粉体

通过在NH4HCO3溶液中滴加Ce（NO3）3、A1（NO3）3和Y（NO3）3的混合溶液,共沉淀生成YAG：Ce的碳酸盐前驱体,对YAG前驱体在不同温度下进行灼烧,并采用IR、XRD和TEM等测试手段对粉体进行表征。结果表明,在1100℃下煅烧YAG前驱体,得到无YAP、YAM中间相的出现纯YAG晶相,所得粉体晶粒直径为20～50nm,具有较好的分散性。同时,荧光测试表明Ce：YAG粉体具有良好的发光性能。     

正交实验优选共沉淀法制备纯相YAG纳米粉体

为了获得制备纯相YAG纳米粉体且重现性好的工艺,本实验以Al(NO3)3·9H2O、Nd2O3、Y2O3和NH4HCO3为原料,(NH4)2SO4为静电稳定剂,采用L9(34)正交试验方案研究了金属离子溶液浓度、NH4HCO3浓度、滴速和pH值4个重要因素对YAG粉体制备的影响,结果表明pH值是影响YAG纯相的主要因素。获得最佳工艺条件并进行了重复性试验研究,均得到了纯相YAG粉体。采用TG/DTA、XRD、FT-IR、TEM等测试手段对YAG粉体及前体进行表征,结果发现在1000℃煅烧温度下前体已完全转变成YAG相,得到了类球形、分散性较好、尺寸为23nm的YAG粉体。     

高分子网络凝胶法制备纳米YAG粉体

以硝酸铝和硝酸钇为原料,采用高分子网络凝胶法制备纳米YAG粉体,对网络凝胶机理和胶体的煅烧过程进行了研究。研究表明干凝胶在900℃煅烧即可全部转变为YAG纯相,没有YAM、YAP等中间相生成。所制备的粉体粒度尺寸大小为20nm左右,颗粒呈球形,有轻微团聚。     

YAG纳米粉体的制备技术研究进展

近年来YAG纳米粉体因其具有特殊的性能而备受人们的关注。以此为原料采用先进的陶瓷制备工艺可以得到透明的YAG固体激光工作介质 ,其物理化学及光学性能可与单晶相比拟。YAG粉体通过掺杂Ce3 ,Tb3 ,Eu3 等离子还可以作为超短余辉荧光粉 ,在发光材料领域有广泛的应用。本文着重介绍了目前应用较多的几种YAG纳米粉体的制备方法 ,并简要地比较了各种方法的优劣。     

超临界流体技术制备超微粉体的新型喷嘴

从结构、功能及特点3方面介绍了一种可实现超临界制备超微粉体的新型喷嘴。该喷嘴不仅能完成单溶质的微粒制备,还可实现超微合成微粒的制备。     

助磨剂在矿渣微细粉制备中的应用与研究

该文研究了几种助磨剂在矿渣微细粉制备中的应用,分析探讨了助磨剂的作用、机理、在使用中应注意的问题及其选择原则。研究结果表明,在矿渣微细粉的制备中引入适当的助磨剂能显著提高微细粉的比表面积、节约单位电耗、降低机械磨耗,而且还能改善微细粉的颗粒形态并使微细粉的粒度分布均匀。     

Synthesis of Nd:YAG powders leading to transparent ceramics: The effect of MgO dopant

Neodymium doped yttrium aluminum garnet (Nd:YAG) ultrafine powders were synthesized by co-precipitation method using MgO as dopant. The addition of small amount of MgO can reduce the agglomeration and particle size of the produced Nd:YAG powders. The results show that pure phase YAG powders can be achieved by calcining of the precursors at 1000 °C for 2 h. The MgO doped Nd:YAG powders show better dispersion compared with the undoped powders. When the MgO content is 0.01 wt.%, well-dispersed Nd:YAG powders with spherical particles of 100 nm diameter were obtained. The transmission of the corresponding Nd:YAG ceramics is 82.6% at the wavelength of 1064 nm, which is comparable to Nd:YAG single crystals.     

Behavior of Ultrafine versus Superfine Powders in a Binary‐Mixture Semi‐Batch Circulating Fluidized Bed

The solid circulation rates of a binary mixture of ultrafine or superfine Al(OH)₃ powders and fluidized catalytic cracking (FCC) particles were investigated in a semi‐batch circulating fluidized bed. The circulation rates were measured at different loadings of fine powders and different equilibrium water contents of the FCC particles. At a certain loading of ultrafine powders, the circulation rates were much smaller than in the presence of the superfine powders. The circulation rates were controlled by the strong cohesive property of the ultrafine powders, irrespective of the water contents of the FCC particles. Slight increases in the circulation rates were observed during fluidization of the ultrafine powders, even at higher equilibrium water contents of the FCC particles.     

Sol–Gel Combustion Synthesis of Nanocrystalline YAG Powder from Metal-Organic Precursors

Yttrium aluminum garnet (Y₃Al₅O₁₂, YAG) nanocrystalline powders were synthesized by a novel sol–gel combustion process. Yttrium acetate and aluminum sec-butoxide were used as the precursors and triethanolamine was used as the chelating agent and fuel. Thermal and crystallization behaviors of the YAG precursor powders were investigated by thermal gravimetric differential thermal analysis (DTA), Fourier transform infrared spectrum, and X-ray diffraction. The combustion-synthesized powders are amorphous and transform to a pure YAG crystalline phase at 900°C. The crystallization activation energy of amorphous YAG precursor was investigated by variable heating rate DTA. The calculated activation energy is 58.9 KJ/mol. The average crystalline size of heat-treated YAG powders at 900°C is ∼20 nm.     

高抗冲聚丙烯颗粒的流动性及其抗静电性

随着气相釜中乙烯含量的增加,高抗冲聚丙烯颗粒会出现发黏、聚并等现象,严重影响其流动性及连续化生产。添加极少量惰性无机超细粉体是减少高抗冲聚丙烯颗粒间粘连的有效措施。通过冷模研究,剖析超细粉体的加入对颗粒流动性的影响,同时探讨体系静电的产生因素及其对颗粒流动性的影响。选用的超细粉体包括球形二氧化硅和层状水滑石。研究发现,相对于直接加入未改性处理的超细粉体,加入经抗静电剂改性的超细粉体后,颗粒的带电量明显减少,落下时间缩短,流动性也得到了有效提高;而且选用水滑石的效果明显优于二氧化硅。     

超细粉体表面包覆技术综述

通过超细粉体的表面包覆以改善粉体的分散性及其表面性质,已经成为超细粉体制备和应用的关键技术。综述了超细粉体的表面包覆方法,包括机械化学法、气相沉积法、聚合物包裹法、液相化学法及微胶囊化法等,主要介绍了每种方法的基本原理及应用。     

The study of surfactant application on synthesis of YAG nano-sized powders

Yttrium aluminum garnet (YAG) nano-sized powders were synthesized using the co-precipitation method with ammonium hydrogen carbonate as precipitant, nonionic, anionic and cationic surfactant as dispersant, respectively. The composition of YAG precursor, the phase formation process of YAG and the properties of the powders were investigated by means of IR, XRD and TEM. The results show that the anionic surfactant is beneficial for the dispersion of the resulting YAG powders. Highly crystalline, well-dispersed nano-sized YAG crystallites were obtained by calcining at 1000 °C for 2 h in the presence of the anionic surfactant. The average size of the particle is about 30 nm. Luminescence properties of the Nd-doped YAG powders prepared with surfactant and with no surfactant were also studied.     

钇铝石榴石粉体制备方法综述

综述了目前YAG粉体材料的几种合成方法,包括高温固相法、溶胶-凝胶法、燃烧法、喷雾热解法和化学沉淀法(化学共沉淀法、分步沉淀法和改进的化学共沉淀法),总结了每种方法的优缺点,并对YAG粉体材料新的合成工艺进行了展望。