兰州大学机构库 >数学与统计学院
氧化硅包覆铁纳米颗粒的熔化
Alternative TitleMelting of iron nanoparticles embedded in silica
丁鹏
Thesis Advisor王连文
2013-05-31
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword晶体熔化 纳米颗粒 机械球磨
Abstract利用机械球磨法制备获得了弥散分布在SiO2基体上的Fe纳米颗粒,进而系统研究了球磨参数对Fe纳米颗粒尺寸的影响规律;在此基础之上,对Fe纳米颗粒的热稳定性以及熔化行为进行了研究。此外,对SiO2包覆的Cu和Ag纳米颗粒的制备及其熔化行为进行了初步探索。 (1) 通过直接球磨Fe和SiO2的混合粉末获得的Fe纳米颗粒多为单晶,平均颗粒尺寸分布集中,并且弥散的分布在SiO2基体上。 (2) 当球磨转速为250rpm时,对于不同Fe/SiO2体积比的样品,Fe纳米颗粒尺寸随球磨时间的变化较为明显,并均在约14h后达到饱和;随着Fe/SiO2的体积比从1:7增加至6:4,最终获得的Fe纳米颗粒的尺寸从约15nm逐渐减小至约9nm。对于Fe/SiO2的体积比为2:8的样品球磨约16h,随着球磨转速从100rpm增加到300rpm,获得的Fe纳米颗粒的尺寸从约33nm降低至13nm;不过,将在200rpm球磨16h的样品继续球磨至50h,Fe纳米颗粒从约22nm逐渐减小至约14nm,表明当转速低于200rpm时球磨进程较为缓慢。 (3) 热分析结果表明,通过提高转速、延长球磨时间和适当的降低混合粉末中Fe的含量可以使Fe纳米颗粒得到更好的包覆和分散。对于平均粒径为15nm的Fe颗粒,其熔点相对于体相降低约30oC,与近期我们的理论计算值符合。
Other AbstractIn this work, to expand the above slim range of materials, the melting behavior of Fe nanoparticles embedded in SiO2 prepared by using mechanical milling are investigated. Effects of factors in sample preparation on the size, isolation and thermal stability of Fe nanoparticles are systematically studied. On this basis, the size-dependent melting of Fe is successfully traced. In addition, preliminary efforts are carried out on the synthesis and melting behaviors of Cu and Ag nanoparticles embedded in SiO2. (i) By direct milling of Fe and SiO2 powders, Fe nanoparticles were obtained which were in principle single crystals with a narrow size distribution and are dispersedly embedded in the SiO2 matrix. (ii) For the milling at 250 rpm, for samples with different Fe-SiO2 volume ratios, the particle size of Fe decreases gradually with extending milling time and finally becomes saturated at around 14 h. With the Fe-SiO2 volume ratio increasing from 1:7 to 6:4, the final particle size of Fe decreased from around 16 nm to 9 nm. For a same Fe content (Fe-SiO2 volume ratio 2:8) milled for 16 h, when the rotational speed increased from 100 rpm to 300 rpm, the size of Fe nanoparticles decreased from about 33 nm to 13 nm. However, for the 2:8 sample milled at 200 rpm for 16 h, when the milling was extended to 50 h, the particle size of Fe further decreased from 22 nm to 14 nm, indicating that the milling process needed a longer time to become complete if the rotational speed was less than 200 rpm. (iii) Results from thermal analyses showed that good isolation of Fe nanoparticles may be obtained by increasing the volume ratio of SiO2 and by extending milling time until the size of Fe nanoparticles became saturated. For Fe nanoparticles with a diameter of about 15 nm, the melting point depression is 30 oC in comparison with bulk Fe, in accordance with our recent theoretical calculations.
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/224542
Collection数学与统计学院
Recommended Citation
GB/T 7714
丁鹏. 氧化硅包覆铁纳米颗粒的熔化[D]. 兰州. 兰州大学,2013.
Files in This Item:
There are no files associated with this item.
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Altmetrics Score
Google Scholar
Similar articles in Google Scholar
[丁鹏]'s Articles
Baidu academic
Similar articles in Baidu academic
[丁鹏]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[丁鹏]'s Articles
Terms of Use
No data!
Social Bookmark/Share
No comment.
Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.