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改进的溶胶-凝胶法制备YAG纳米粉体 总被引:7,自引:0,他引:7
采用低成本的无机有机复合体系的溶胶凝胶法成功制备出了Y3Al5O12 (YAG)纳米粉体。实验中通过将Y(NO3)3 和Al(NO3)3 按摩尔比3:5 溶解于异丙醇中,再加入适量柠檬酸后生成溶胶,经过脱醇、干燥形成纳米胶球前驱体,将其在适当温度下焙烧后生成YAG纳米粉体。在此过程中,采用了独特的循环水真空泵负压脱醇技术,大大缩减了脱醇和干燥时间,由40h降为4h。分别采用XRD,TEM和TG/DTA分析了不同温度下焙烧所得粉体的物相、形貌以及前驱体热分解特性。结果表明,与其它有机和无机体系制备方法相比,得到的YAG粉体颗粒近似球形,细小均匀,平均尺寸为20~40nm,并具有很好的分散性。 相似文献
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改性的沉淀法制备三氧化二钇粉体 总被引:6,自引:0,他引:6
以Y(NO3)3和NH4HCO3为原料,添加适量的表面活性剂(聚乙烯醇)和(NH4)2SO4,利用改性的沉淀法制备了Y2O3前驱体。对前驱体在不同温度下进行焙烧,成功制备了超细Y2O3纳米粉体。分别采用XRD、TEM和TG—DTA分析了不同温度下煅烧所得粉体的物相、形貌以及前驱体热分解特性。结果表明,前驱体在900℃下保温1.5h,得到的Y2O3粉体颗粒近球形,细小均匀,平均尺寸约为7nm,粒径分布极窄,并具有很好的分散性和流动性。 相似文献
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采用沉淀法以六水氯化镁(MgCl_2·6H_2O)和氨水(NH_3·H_2O)为原料制备出氢氧化镁,热解得到了片状镂空纳米氧化镁。利用Kissinger法计算出氢氧化镁的热解表观活化能E和指前因子A,并用Ozawa-Flynm-Wall方程法进行了验证;采用Satava法分析得出氢氧化镁热解机理为随机成核及生长;通过TEM和SAED分析,该氧化镁纳米级平均粒径在20 nm左右,微米级尺寸在200~500 nm之间,暴露晶面族为{110};经XRD分析,氧化镁微纳结构的形成机理与前驱体热解过程中分解产物逸出方式以及晶体结构变化有关。 相似文献
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采用水热法制备了BaO-Nd2O3-TiO2(BNT)系纳米粉体。在KOH碱性溶液中,以TiCl4,BaCl2和Nd(NO3)3为反应物,先制备出BaO-Nd2O3-TiO2(BNT)凝胶前驱体,再经低温水热处理,得到BNT系纳米粉体。产物通过XRD、IR、TEM等手段进行测试分析,结果表明:该法获得的BNT系纳米粉体为立方相结构,稀土元素掺杂均匀,产物粒径小,分散度高。讨论了BNT系纳米粉体的形成机理,发现凝胶前驱体的存在有利于BNT系纳米粉体的成功制备。 相似文献
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将溶胶-凝胶法与微波自然烧法相结合,利用微波诱发自燃烧技术一步合成了Bi3.25La0.75Ti3O12(BLT)纳米粉体.根据相关络合反应及其反应平衡常数所进行的理论计算,确定了前驱体溶液的最佳pH值和柠檬酸(CA)/金属离子(M)的物质的量比.分别利用红外光谱(FTIR)、X射线衍射(XRD)和扫描电镜(SEM)对前驱体及合成的纳米粉体进行了表征,结果表明,微波诱发溶胶-凝胶自燃烧法能一步合成具有层状钙铁矿结构的单相BLT纳米粉体.当pH=6、n(CA)/n(M)=2.5以及氧化度Q=80 %时,合成的单相BLT纳米粉体的平均晶粒尺寸约为30nm. 相似文献
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To enhance the electronic properties of nanoparticles, functional clusters are usually supported on metal oxides as alumina. Copper and nickel clusters supported on magnesia or alumina are promising materials to catalyze the decomposition of methane to produce hydrogen. A mixed support of alumina and magnesia can be proposed in the form of a hydrotalcite. In this work, the synthesis of hydrotalcites containing Cu, Ni, Mg and Al in the presence of microwave irradiation is studied. Cu/Al hydrotalcite which is hardly synthesized through conventional methods was easily prepared in the presence of microwaves. 相似文献
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In order to overcome limitations in the processing parameters of powder compaction method, a novel processing technique based on sol-gel route has been developed to produce near-net-shaped prototype fine zirconia minispheres with required properties that could potentially be used as grinding media. Impact of magnesia concentration and sintering temperature on the final product has been analyzed in detail. Zirconia minispheres have been characterized to establish a correlation between physical, structural and mechanical properties. Sintering temperature, soaking period, heating rate and viscosity of the sol apparently influence the characteristics of the magnesia stabilized zirconia minispheres. The phase identification, density variation, chemical decomposition, functional group specification, surface area, porosity, shrinkage and microstructural features of the dried and sintered final product have been studied. It has been observed that magnesia content, sintering temperature, density and the grain size of the sintered minispheres have a significant impact on the mechanical properties of the final product. 相似文献
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纳米二氧化钛粉体晶相控制实验研究 总被引:12,自引:0,他引:12
在水解-沉淀法制备纳米TiO2粉体的过程中,使用不同的沉淀剂获得了晶相不同的纳米TiO2粉体,使用混合沉淀剂,通过控制沉淀剂的比例,制备了晶相组成(金红石与锐钛矿比例)不同的纳米TiO2多晶粉体,采用相同的粉体制备工艺,不同的后续处理工艺,探讨了锐钛矿向金红石转变的相变温度,经分析研究后认为,水解-沉淀法制备的纳米粉体中的锐钛矿向金红石红转变的温度为500-800℃,完全转变的温度在800℃以上;纳米TiO2多晶粉体的晶相组成不仅与沉淀剂的种类,混合沉淀剂中沉淀剂的比例和粉体的煅烧温度有关,而且与粉体的后续处理工艺和粉体表面界面相的稳定性有关。 相似文献
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基于一种新型的纳米二氧化钛(TiO2)粉体,利用熔体共混方式制备了纳米TiO2/聚丙烯(PP)复合材料,研究了复合材料的相分散结构、结晶特性、力学性能、杀菌性能和流动性能。结果发现:新型纳米TiO2在聚丙烯中有较好的分散度,绝大多数纳米TiO2在聚丙烯中的聚集体尺寸接近于100纳米;新型纳米TiO2对聚丙烯有一定的结晶成核作用,但并不能提高结晶度;复合材料的力学性能随纳米TiO2含量的增加呈现出拉伸强度下降,伸长率降低,模量和冲击强度上升的趋势。2%纳米TiO2含量的聚丙烯复合材料的综合物理机械性能较好。新型纳米TiO2填充到PP中可以起到良好的抗菌杀菌作用,但也在一定程度上使聚丙烯发生氧化降解,进而导致纳米TiO2/聚丙烯复合材料的流动性略优于纯聚丙烯。 相似文献
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Crouch D Norager S O'Brien P Park JH Pickett N 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2003,361(1803):297-310; discussion 310
Various methods for the synthesis of quantum dots of compound semiconductors are discussed. Emphasis is placed on methods involving the decomposition of chalcogenide-containing precursors in tri-n-octylphosphine oxide. The use of simple coordination complexes can avoid the use of pyrophoric precursors. Approaches based on melts or the use of imino-bisdichalcogeno-diphosphinates are also discussed. These routes may be suitable for the production of large quantities of quantum dots. 相似文献
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为了进一步提高金属陶瓷的力学性能及其刀具的高速切削性能, 研究了纳米增强金属陶瓷的显微组织特征和热冲击性能。扫描电镜和透射电镜分析表明: 组织中陶瓷相呈现典型的芯2壳结构特征; 芯为TiC 或Ti (C ,N) , 而壳则为( Ti ,Mo ,W) (C ,N) 固溶体。纳米增强金属陶瓷机制为细晶强化、弥散强化和固溶强化。热冲击实验表明: 随着热循环的进行, 材料中孔洞的数量、孔洞的尺寸以及微裂纹的尺寸随之增大; 同时, 热循环过程中出现的表面氧化、裂纹长大、偏转以及桥接现象也很显著。与常规Ti (C ,N) 金属陶瓷相比, 纳米增强金属陶瓷的抗热冲击性能明显提高。 相似文献
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The change in strength of hydratable alumina-bonded castable refractories in the presence of magnesia powder and magnesia aggregate, after heat treatment at 110∘ and 816∘C, and the relationship between the strength and morphology and thermal decomposition behavior of the hydrates in the castables are investigated. The mechanism of bonding facilitated by the presence of magnesite in hydratable alumina-bonded castables after drying is discussed. The contribution of polycondensation process occurring after dehydroxylation of the hydrates in the castables after firing at 816∘C is proposed as the principal mechanism for strength development. 相似文献
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采用聚氨酯、中空玻璃微球和纳米材料3种方式对环氧电子灌注材料进行了改性,研究了改性方式对密度、冲击韧性和压缩性能的影响。结果表明:中空玻璃微球改性对密度降低最大,比纯环氧降低了20%左右,密度达到近1.0g/cm^3,聚氨酯改性的冲击韧性最高,纳米材料改性能显著提高压缩性能。 相似文献
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A thorough review on the patents in the applications of nano-powder technology shows that research work in this technical field is growing stronger, as indicated by a rapid increase in the number of independent patents in relevant topics. This also indicates ever increasing and continuous interests on the nano-powder technology even after 15 years of dynamic global nanotechnology development. The review on the patents in the nano-powder area shows that the use of specialized databanks is recommendable and beneficial in providing the researchers in this technical community an updated, systematic and rapid reference in furthering new development and expansion of this vital nanotechnology field. 相似文献