期刊
ADVANCED POWDER TECHNOLOGY
卷 32, 期 8, 页码 2733-2742出版社
ELSEVIER
DOI: 10.1016/j.apt.2021.05.044
关键词
Al2O3 nanoparticles; Size effect; Laser vaporization; Physical vapor deposition; F-centers; 3d elements; Hydroxyl groups
资金
- Russian Foundation for Basic Research [19-32-60027]
- Ministry of Science and Higher Education of the Russian Federation [AAAA-A21-121011390009-1]
Al2O3 nanoparticles with sizes ranging from 2 to 21 nm were synthesized by vaporization of alpha-Al2O3 in different gases and pressures using a CO2 laser. The properties of the nanopowders were affected by synthesis conditions, with smaller particles exhibiting faceted shapes and larger particles being closer to spherical. The nanoparticles exhibited photoluminescence at room temperature and 80 K due to trace impurities and defects.
A series of Al2O3 nanoparticles with the sizes ranging from similar to 2 to 21 nm, according to XRD, HRTEM and BET, was obtained by vaporization of alpha-Al2O3 in flowing helium and argon at different pressures under the action of a cw CO2 laser. The particle size was changed by varying the composition of ambient gas (He, Ar) and its pressure in a vaporization chamber from 0.034 to 0.9 bar. The effect of the synthesis conditions on the properties of Al2O3 nanopowders is presented and discussed. Particles with the size smaller than 6-7 nm have a faceted shape, whereas the shape of larger particles is close to spherical. It was found that the resulting nanopowders consist of a mixture of transition aluminas, among which the cpolymorph is dominant. Thermal analysis showed that for smaller nanoparticles the phase transition to alpha-Al2O3 occurs at a lower temperature. In nominally pure Al2O3 nanoparticles with different sizes, photoluminescence at RT and 80 K is determined by trace level concentrations (<= 10(-3) wt%) of uncontrolled impurities of 3d elements (Cr3+(Oh) and Fe3+(Td)), surface hydroxyl groups, and point defects represented mostly by F-type centers. The acquired experimental data indicate that manifestation of the size effect for Al2O3 nanoparticles has a boundary corresponding to 6-7 nm. Al2O3 nanoparticles with the dominant gamma-Al2O3 structure obtained by the laser method can be promising in many chemical reactions, particularly as the supports of catalysts and sorbents, for which the high specific surface area is of special importance. (C) 2021 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据