A V Radha
Articles written in Bulletin of Materials Science
Volume 26 Issue 7 December 2003 pp 661-666 Sol-gel Materials
Volume 27 Issue 4 August 2004 pp 355-360 Electrode Materials
The layered double hydroxide (LDH) of Zn with Cr on treatment with a hypochlorite solution releases chromate ions as a result of oxidative leaching by a dissolution–reprecipitation mechanism. The residue is found to be 𝜀-Zn(OH)2. The LDH of Mg with Cr on the other hand is resistant to oxidative leaching. In contrast, a X-ray amorphous gel of the coprecipitated hydroxides of Mg and Cr yields chromate ions. These results suggest that the oxidation potential of Cr(III) in LDHs is determined by the nature of the divalent ion and the crystallinity of the phase while being unaffected by the nature of the intercalated anions.
Volume 33 Issue 3 June 2010 pp 319-324 Catalysis
The layered double hydroxide (LDH) of Co with Al decomposes to yield an oxide residue with the spinel structure below 250°C. The decomposition reaction is preceded by the formation of an intermediate hydroxide in which the metal hydroxide layers are regularly stacked about the 𝑐-crystallographic axis, but the layers themselves are aperiodic. Aperiodicity is modeled by locating randomly chosen Co2+ ions in tetrahedral sites in the interlayer region. This phase is characterized by a single strong basal reflection in its powder diffraction pattern. All other reflections are extinguished on account of
turbostratic disorder which destroys all ℎ𝑘𝑙 reflections and
layer aperiodicity, which destroys all two dimensional ℎ𝑘 reflections.
Given its topochemical relationship with the spinel structure, such an intermediate is a necessary precursor to spinel formation.
Volume 42 | Issue 5