聚乙烯醇作保护剂的反滴定共沉淀法制备纳米晶LaFeO_3

以聚乙烯醇或十二烷基苯磺酸钠作保护剂,采用反滴定共沉淀法制备纳米晶LaFeO_3的前体.     

网状结构对Fe72Y6B22非晶合金晶化行为和软磁性能影响的研究

对Fe72Y6822非晶合金的晶化行为和软磁性能进行了研究.分子动力学模拟结果显示,合金熔体中的团簇结构主要为〈0,3,6,0〉型多面体;实验结果显示,在合金的退火样品中存在由冠状三棱柱组成的网状结构.这种网状结构可提高合金在过冷液相区的热稳定性,抑制合金的晶化,改变合金的晶化方式,促进纳米α-Fe晶粒的形成.适当的退火工艺可以提高Fe72Y6822非晶合金的软磁性能.合金饱和磁化强度和矫顽力的变化是由于晶化过程的不同阶段析出纳米晶oc-Fe相、顺磁性的YB12相和弱磁性的Fe3B相所致.     

Fe_(77.3)Cu_(0.7)Nb_(1.3)Si_(13.5)B_(7.2)合金磁性的研究

研究了非晶 Fe_(77.3)Cu_(0.7)Nb_(1.3)Si_(13.5)B_(7.2)合金在400～600℃的温度范围内退火后磁性的变化。磁性测量结果表明,获得高磁导率的最佳退火温度约540℃左右;经 X 射线衍射分析证实:在该温度下退火,非晶态合金已经晶化并形成体心立方结构的α—FeSi 固溶体,其晶粒直径约10～15nm。这种超细晶粒的纳米晶是高磁导率的根源。     

纳米晶软磁材料的磁性与巨磁阻抗效应

介绍了国内外纳米晶软磁FINEMET合金的制备方法、软磁特性、巨磁阻抗效应和物理机制,尤其对巨磁阻抗效应的研究、应用及展望作了较详细的评述．     

Stabilization of mesoporous nanocrystalline zirconia with Laponite

The mesoporous nanocrystalline zircoina was synthesized via solid state reaction structure directing method in the presence of Laponite. The introduction of Laponite renders the higher thermal stability and lamellar track to the zireonia. Laponite acts as inhibitor for crystal growth and also hard template for the mesostructure. The role of Laponite is attributed to the interaction between the zireonia precursors and the nano-platelets of Laponite via the bridge of hydrophilic segments of surfactant. It results in the formation of Zr-O-Mg-O-Si frameworks in the direction of Laponite layer with the condensation of frameworks during the calcination process, which contributes the higher stability and lamellar structure to the nano-sized zireonia samples.     

Nanocrystalline TiO2 thin film electrodes prepared by common pressure hydrothermal method at low temperature

Dye-sensitized solar cells (DSSCs) based on nanocrys- talline TiO2 thin film electrodes have been widely investi- gated since they were invented by Gr?tzel et al. in 1991[1-3]. Nanocrystalline TiO2 thin film electrodes are usually pre- pared by coating TiO2 colloid with organic additives on conductive glass substrates and annealing at 400-450℃ to remove organic additives and achieve good electrical contact between TiO2 particles and between TiO2 particles and conductive substrates, which…     

Si4+掺杂对镁铝水滑石纳米晶体结构与性能的影响

研究了Si4 掺杂对镁铝水滑石[Mg6Al2(OH)16CO3]·4H2O阻燃剂制备的影响,讨论了以NaAlO2为铝源,不同的Si4 掺杂浓度对所得镁铝水滑石试样的相组成以及其晶粒大小和结晶状态的影响.结果表明:在Na2SiO3的掺入浓度小于等于0 012mol/L的范围内,可以成功地进行Si4 掺杂,Si4 进入到镁铝水滑石基本层中的羟基八面体空间,使镁铝水滑石晶体的颜色由白色变为天蓝色,抑制了镁铝水滑石晶体的长大.DSC TG热分析表明,Si4 掺杂提高了镁铝水滑石第二次热分解的终止温度点,将其热分解温度范围拓宽了约17℃,最终热分解物的残余量提高了5 5%,从而提高了镁铝水滑石阻燃剂的热稳定性.     

Fe-Nb-B纳米晶合金的结构与磁性

利用X射线衍射,差热分析及静态磁性测量,研究了退火温度对不同成分的非晶Fe Nb B合金纳米晶化行为和磁性的影响·实验发现:在纳米晶化过程的初期出现磁硬化,矫顽力与最大磁导率均呈现不同程度的恶化·在硼化物(Fe2B和Fe3B)相析出前,具有纳米结构的合金由α Fe固溶体和非晶基体相组成,呈现较佳的软磁特性·随纳米晶相体积分数增加而呈现的磁软化现象可解释为由于纳米晶粒间距的减少,交换耦合增强所致·     

纳米TiO2降解源复合型农药制剂

采用压电石英微天平技术研究了有机农药甲基对硫磷在经硬脂酸改性前、后纳米TiO2上的吸附行为.研究结果表明:硬脂酸能提高纳米TiO2对非极性有机农药的吸附量,甲基对硫磷分子在改性后的纳米TiO2上的吸附符合Langmuir吸附,最大吸附量Г∞为1.4×10-3mol/g,吸附常数k为5.5×105L/mol;亲脂性农药可与硬脂酸改性后的纳米TiO2形成稳定的复合体,复合纳米TiO2农药制剂可在太阳光照下自行降解,在农作物体内的残留期大大缩短,且复合纳米TiO2农药制剂的毒力明显提高,质量分数为10％的纳米乳液的毒力是质量分数为95％的原药毒力的1.68倍.     

Photoelectrical performance of nanocrystalline TiO2 film electrode sensitized by Ru(II)-bipyridine complexes

Two kinds of Ru(II)-bipyridine complexes,cis-di(thiocyanate)bis(2,2′-bipyridyl-4,4′-dicarboxylate) ruthenium(II) andcis-di(thiocyanate)bis(2, 2′-bipyridyl-3, 3′-dicarboxylate) ruthenium(II), were utilized as the sensitizers to the nanocrystalline TiO₂ film electrodes. Study shows that the two dyes have quite different sensitization properties due to the strong steric effect of carboxyl groups. In addition, the pretreatment to nanocrystalline TiO₂ film electrodes with TiCl₄ was investigated, which is an effective way to improve the photoelectric conversion performances of sensitized TiO₂ electrodes.