Thermally Induced Formation of Transition Aluminas from Boehmite1 . Issue 9 (2nd May 2017)

• Record Type: Journal Article
• Authors: Rudolph, Martin; Salomon, Anton; Schmidt, Anne; Motylenko, Mykhaylo; Zienert, Tilo; Stöcker, Hartmut; Himcinschi, Cameliu; Amirkhanyan, Lilit; Kortus, Jens; Aneziris, Christos G.; Rafaja, David
• Other Names: Aneziris Christos guestEditor.; Fey Tobias guestEditor.
• Is Part Of: Advanced engineering materials. Volume 19:Issue 9(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-05-02
• Subjects: Materials -- Periodicals; 620.11
• DOI: 10.1002/adem.201700141
• Languages: English
• ISSNs: 1438-1656

Abstract

Abstract : Structural changes occurring during the conversion of boehmite over the transient phases γ‐, δ‐ and θ‐Al2 O3 to corundum were investigated. During the whole transition process, the specific surface area was reduced. The X‐ray and electron diffraction experiments revealed that the transition from γ‐ to θ‐Al2 O3 is continuous and that it proceeds over different δ‐states rather than over a distinct δ‐Al2 O3 phase. The reduction of the specific surface area was most pronounced prior to the onset of the phase transition from γ‐Al2 O3 to the first δ‐state. In γ‐Al2 O3, approximately 45% of Al cations were found to be located on tetrahedral sites within a slightly tetragonal distorted oxygen sublattice. Abstract : The results of selected area electron diffraction, X‐ray diffraction, and thermal analysis have shown that the thermally induced phase transitions in metastable alumina phases, which are usually characterized by the sequence γ ‐, δ ‐, and θ ‐Al2 O3, can alternatively be described as a continuous process.