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Title: Structure of oxides prepared by decomposition of layered double Mg–Al and Ni–Al hydroxides

Abstracts: Thermal decomposition of Mg–Al and Ni–Al layered double hydroxides LDH at temperatures lower than 800 °C leads to the formation of oxides with different structures. Mg–Al oxide has a very defective structure and consists of octahedral layers as in periclase MgO and mixed octahedral–tetrahedral layers as in spinel MgAl{sub 2}O{sub 4}. Mixed Ni–Al oxide has a sandwich-like structure, consisting of a core with Al-doped NiO-like structure and some surface layers with spinel NiAl{sub 2}O{sub 4} structure epitaxial connected with the core. Suggested models were verified by simulation of X-ray diffraction patterns using DIFFaX code, as well as HRTEM, IR-, UV-spectroscopies, and XPS. - Graphical abstract: In the Mg–Al layered double hydroxide Al{sup 3+} ions migrate into interlayers during decomposition. The Mg–Al oxide represents sequence of octahedral and octahedral–tetrahedral spinel layers with vacancies. The Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers as a result of migration of Al{sup 3+} ions on the surface. The models explain the presence and absence of “memory effect” for the Mg–Al and Ni–Al oxides, respectively. - Highlights: • We study products of Mg(Ni)–Al LDH decomposition by calcination at 500(400)–800 °C. • In Mg–Al/Ni–Al LDH Al ions migrate into interlayers/onmore » the surface during decomposition. • Mg–Al oxide represents sequence of periclase- and spinel-like layers with vacancies. • Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers. • The models explain the presence/absence of “memory effect” for Mg–Al/Ni–Al oxides.« less
Authors:
 [1] ;  [2] ;  [3] ; ;  [3] ;  [3] ;  [2] ;  [3]
  1. Boreskov Institute of Catalysis Siberian branch of Russian Academy of Sciences, pr. Lavrentieva 5, Novosibirsk 630090 (Russian Federation)
  2. (Russian Federation)
  3. Institute of hydrocarbons processing Siberian branch of Russian Academy of Sciences, Neftezavodskaya, 54, Omsk 644040 (Russian Federation)
Publication Date:
OSTI Identifier:
22475623
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 225; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; ALUMINIUM HYDROXIDES; ALUMINIUM IONS; CALCINATION; DOPED MATERIALS; EPITAXY; HYDROXIDES; LAYERS; MAGNESIUM OXIDES; NICKEL OXIDES; SPINELS; SURFACES; TEMPERATURE DEPENDENCE; TRANSMISSION ELECTRON MICROSCOPY; VACANCIES; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY