A Structural Study of Stacking Disorder in the Decomposition Oxide of MgAl Layered Double Hydroxide: A DIFFaX plus Analysis

Rune E. Johnsen, Poul Norby

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The structure of the decomposition oxide of a nitrate-based magnesium-aluminum layered double hydroxide (LDH) was studied in detail by means of the DIFFaX+ refinement program. The DIFFaX+ refinement was based oil an in situ X-ray powder diffraction pattern (XRPD) collected at 890 degrees C and showed that the decomposition oxide is a disorder phase, where periclase-type layers and spinel-OT-type layers with different cation concentration and distribution are stacked along the direction corresponding to the cube diagonal of the ideal cubic periclase and/or spinel structure. The spinel-OT-type layers in the periclase-like decomposition phase are assumed to contain significant amounts of tetrahedrally coordinated aluminum atoms Furthermore, the DIFFaX+ refinement of the decomposition oxide indicated that the octahedra and tetrahedra of the spinel-OT-type layer and the octahedra of some of the periclase-type layer are distorted due to deviation in the cubic-close packing of the oxygen atoms in the decomposition oxide. Our detailed structural investigation described the disorder present in the periclase-like decomposition oxide and revealed the origin of an additional major diffraction peak tit the powder diffraction pattern which has up to now remained unexplained.
Original languageEnglish
JournalJournal of Physical Chemistry Part C: Nanomaterials and Interfaces
Volume113
Issue number44
Pages (from-to)19061-19066
ISSN1932-7447
DOIs
Publication statusPublished - 2009
Externally publishedYes

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