共查询到17条相似文献,搜索用时 78 毫秒
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在表面活性剂聚乙烯吡咯烷酮(PVP)存在的体系中,通过NaBH4还原前驱体Fe(acac)3和H2PtCl6·6H2O,制备出了单分散的尺寸在3.0 nm左右的FePt纳米颗粒。XRD和TEM表征结果显示,表面活性剂PVP的用量影响FePt纳米颗粒相变,但对颗粒的尺寸无明显作用。由此推测,PVP对FePt纳米颗粒的相变起"催化"作用,适量的PVP诱导纳米颗粒的相变,可以通过改变表面活性剂的用量来调节FePt纳米颗粒的磁性能,当表面活性剂PVP单体与FePt前驱体的摩尔比(PVP/FePt)为7时,制得的FePt纳米颗粒经过500℃保温30 min热处理后,矫顽力高达5.2 kOe。 相似文献
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以乙酰丙酮铁和氯铂酸作为Fe源和Pt源,1,2-十二烷二醇为还原剂,通过多元醇还原法制备出单分散的FePt纳米颗粒,研究了表面活性剂油酸和油胺对FePt纳米颗粒形貌和分散性的影响。结果显示,未使用表面活性剂制得的FePt纳米颗粒粒度范围是1.0~6.0 nm,平均粒径为3.4 nm;使用油酸和油胺制得的FePt纳米颗粒粒度范围是2.5~5.5 nm,平均粒径4.1 nm。通过XRD、TEM和VSM分析表明,油酸和油胺修饰的FePt纳米颗粒为面心立方结构,形状近似球形,分散性良好,粒径分布较未使用表面活性剂时变窄;VSM显示其矫顽力趋近于0,呈现超顺磁性。 相似文献
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表面活性剂在纳米氧化铅粉体合成中的应用 总被引:4,自引:0,他引:4
在PbAc4与Na2CO3反应体系中,加入表面活性剂(SAA)作为胶团分散剂,实验结果表明:随SAA质量分数增大,产物四氧化三铅(Pb3O4)粒径逐渐变小,当SAA质量分数达到一定(临界下限)值时,就可以得到纳米级Pb3O4;当SAA质量分数达到一定(监界上限)值时,Pb3O4粒度不再变小。复配表面活性剂质量分数下限为3.0%、上限为5.2%时,红丹粒径最小,平均粒度25nm,为单分散球形粒子。非离子表面活性剂质量分数下限为4.1%、上限5.2%,可得到片状纳米Pb3O4粒子。阴离子表面活性质量分数下限3.1%,上限5.2%,纳米Pb3O4粒子为串珠状。 相似文献
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表面活性剂在纳米材料科学中的应用 总被引:5,自引:0,他引:5
介绍了表面活性剂在纳米材料制备及其表面改性等方面的应用,表面活性剂对纳米材料粒度与形状的影响,并展望了表面活性剂在纳米材料科学以及其他高新技术产业的应用前景。 相似文献
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The present paper describes ordered alloy FePt nanoparticles with high magnetic susceptibility to alternate current (ac) fields at around room temperature for biomedical applications such as magnetic sensing devices for diagnostics and magnetic hyperthermia for cancer therapy. Since ac magnetic susceptibility takes the maximum value at a temperature near the blocking temperature of magnetic nanoparticles, the blocking temperature of the FePt nanoparticles is required to be adjusted at around room temperature to improve biomedical performances. Ordered alloy FePt has much higher magnetic anisotropy than iron oxides, and it can be the best candidate in the case of their particle size less than 10 nm. The ordered alloy FePt nanoparticles are synthesized by reduction of Fe and Pt organo-metallic compounds with tetraethylene glycol using poly(N-vinyl-2-pyrrolidone) (PVP) as a protective agent. PVP is a water-soluble polymer, and is proper to obtain dispersion into water. Influences of reaction temperature on crystallite size (particle size) and blocking temperature and the relationship between the blocking temperature and the value of ac magnetic susceptibility at around room temperature are investigated. Furthermore, PVP concentration at the synthesis to obtain well dispersed nanoparticle-suspension is examined. 相似文献
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FePt nanoparticles with average size of 9 nm were synthesized using a diblock polymer micellar method combined with plasma
treatment. To prevent from oxidation under ambient conditions, immediately after plasma treatment, the FePt nanoparticle arrays
were in situ transferred into the film-growth chamber where they were covered by an SiO2 overlayer. A nearly complete transformation of L10 FePt was achieved for samples annealed at temperatures above 700 °C. The well control on the FePt stoichiometry and avoidance
from surface oxidation largely enhanced the coercivity, and a value as high as 10 kOe was obtained in this study. An evaluation
of magnetic interactions was made using the so-called isothermal remanence (IRM) and dc-demagnetization (DCD) remanence curves
and Kelly–Henkel plots (ΔM measurement). The ΔM measurement reveals that the resultant FePt nanoparticles exhibit a rather weak interparticle dipolar coupling, and the absence
of interparticle exchange interaction suggests no significant particle agglomeration occurred during the post-annealing. Additionally,
a slight parallel magnetic anisotropy was also observed. The results indicate the micellar method has a high potential in
preparing FePt nanoparticle arrays used for ultrahigh density recording media. 相似文献
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新型阴离子孪连表面活性剂的合成 总被引:1,自引:0,他引:1
系列长链环氧烷与不同短链二醇在75~80℃、NaH作用下合成了系列中间体孪连长链二醇,此中间体再与1,3-丙烷磺酸内酯在THF、NaH中反应得到了疏水链长度和连接基长度不同的7种磺酸盐孪连表面活性剂。核磁共振氢谱及红外光谱的结构分析证实了它们的结构。它们的表面张力为26.5~34 mN/m,临界胶束浓度为0.001~0.01 mmol/L,结果表明,它们的表面活性比相应碳链的常规表面活性剂强很多。疏水链长度和连接基长度的增长,有助于表面活性的提高。 相似文献
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在对甲苯磺酸的催化下,庚醛、癸醛分别与3-氯-1,2-丙二醇通过缩合反应制备了氯代缩醛2-烷基-4-氯甲基-1,3-二氧杂环戊烷;再分别与亚硫酸钠进行磺化反应,合成了缩醛型可分解表面活性剂(2-烷基-1,3-二氧杂环-4)甲烷-1-磺酸钠盐,磺化产率分别为87.9%和87.3%;所得中间体和产物的结构经IR、1HNMR表征。对缩合反应的物料摩尔比、催化剂用量、反应时间等进行了优化,结果表明:n(庚醛)∶n(3-氯-1,2-丙二醇)=1∶1.2,对甲苯磺酸0.4g,反应时间20h为较佳合成条件,产率达66.51%~68.70%。测试了可分解表面活性剂Ⅱa、Ⅱb在盐酸溶液中的分解率,结果显示:分别在1.5、3h,分解率就可达100%。 相似文献
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SPE与红外光谱相结合鉴定复配表面活性剂 总被引:2,自引:0,他引:2
海关依据HS编码(Harmonized System Code)对各种商品进行分类管理,所有海关样品的特点都是时效性非常强。要在短时间内确定复合表面活性剂商品的编码一直是海关样品检验的难点。通过选择适合的固定相萃取(SPE)小柱和适合的洗脱溶剂快速分离复配表面活性剂,在此基础上用红外光谱鉴定分离出的表面活性剂。结果表明,应用固相萃取与红外光谱结合的方法能快速、可靠地鉴定复配表面活性剂中所含表面活性剂的类型及成分,可以满足海关表面活性剂类样品商品归类的分析要求。该分析方法目前已应用于中国检验检疫公司福州马尾分公司的表面活性剂类商品HS编码的归类分析。 相似文献