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2019.10.25 Science: 生成和稳定α- Al2O3刚玉纳米颗粒

 

Science  25 Oct 2019:
Vol. 366, Issue 6464, pp. 485-489
DOI: 10.1126/science.aaw9377

 
REPORT
High-surface-area corundum by mechanochemically induced phase transformation of boehmite
Amol P. Amrute1,*
Zbigniew Łodziana2
Hannah Schreyer1, 
Claudia Weidenthaler1
Ferdi Schüth1,*
 
Milling corundum nanoparticles
High-purity corundum (α-Al2O3) nanoparticles could enable applications such as more stable catalyst supports or precursors for high-strength ceramics. Milling of corundum only produces micrometer-scale particles, and direct synthesis from other aluminum oxides that would be likely starting materials, such as γ- Al2O3, fails because of the high activation barrier for converting the lattice structure of these cubic close-packed oxides. Amrute et al. show that ball milling of boehmite, γ-AlOOH, created ∼13-nanometer-diameter corundum nanoparticles of high purity through a mechanically induced dehydration reaction and by the effect of milling impacts on the surface energy of the particles.

Abstract
In its nanoparticulate form, corundum (α- Al2O3) could lead to several applications. However, its production into nanoparticles (NPs) is greatly hampered by the high activation energy barrier for its formation from cubic close-packed oxides and the sporadic nature of its nucleation. We report a simple synthesis of nanometer-sized α- Al2O3 (particle diameter ~13 nm, surface areas ~140 m2 g−1) by the mechanochemical dehydration of boehmite (γ-AlOOH) at room temperature. This transformation is accompanied by severe microstructural rearrangements and might involve the formation of rare mineral phases, diaspore and tohdite, as intermediates. Thermodynamic calculations indicate that this transformation is driven by the shift in stability from boehmite to α- Al2O3 caused by milling impacts on the surface energy. Structural water in boehmite plays a crucial role in generating and stabilizing α- Al2O3 NPs.
 
 
 
1 Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany.
2 INP, Polish Academy of Sciences, ul. Radzikowskiego 152, PL- 31-342 Kraków, Poland.
↵*Corresponding author. Email: amrute@kofo.mpg.de (A.P.A.); schueth@kofo.mpg.de (F.S.)
 
德国马克斯·普朗克煤炭研究所研究人员开发了一种在室温下通过勃姆石(γ-AlOOH)合成纳米级α- Al2O3粒径〜13 nm,表面积〜140 m2 g-1)的简便方法。这种机械化学脱水的方法对勃姆石(γ-AlOOH)进行球磨,通过机械诱导的脱水反应,且球磨对颗粒表面能的影响,制备出直径约13 nm的高纯度刚玉(α- Al2O3)纳米颗粒。热力学计算表明,这种从γ-AlOOH石到α- Al2O3的稳定转化是由于研磨对表面能的影响所引起。γ-AlOOH中的化合水在生成和稳定α- Al2O3纳米颗粒中起着至关重要的作用。
 
此研究工作于2019年10月25日在线发表在Science 上,文题为“High-surface-area corundum by mechanochemically induced phase transformation of boehmite”。
 

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