Document Details

Document Type : Article In Journal 
Document Title :
Activation and local structural stability during the thermal decomposition of Mg/Al-hydrotalcite by total neutron scattering
Activation and local structural stability during the thermal decomposition of Mg/Al-hydrotalcite by total neutron scattering
 
Subject : Chemistry 
Document Language : English 
Abstract : The activation of synthetic hydrotalcite, the carbonated layered double hydroxide (LDH) with ratio Mg 2+/Al 3+ = 3 and structural formula [Mg 6Al 2(OH) 16] 2+· CO 3 2-n(H 2O), has been investigated using neutron and X-ray diffraction. In situ neutron diffraction was used to follow the structural phase transformations during the thermal decomposition (calcination) of hydrotalcite under vacuum in the temperature range 298-723 K, and during which the residual gas evolved by the sample was analysed by mass spectrometry. Detailed structural information of the LDH and mixed metal oxides (MMOs) was extracted from both the Bragg peaks and the total scattering. These two analysis techniques provide complementary insight into the relevant transition mechanisms, since Bragg diffraction originates from long-range periodicities within the samples while total scattering reveals the subtleties of the local atomic environment. This latter information is particularly important for our understanding of catalytic activity since it elucidates the local metal coordination. We find that, during the calcination process, the local environment around the metal centres is robust, as the various stages during the phase transition have identical local structures. The implications of these new results for the nature of the MMOs is discussed in relation to the well-studied, reverse, rehydration reaction, and the high propensity of trivalent Al ions to migrate to tetrahedrally-coordinated lattice sites. 
ISSN : 0959-9428 
Journal Name : Journal of Materials Chemistry 
Volume : 21 
Issue Number : 39 
Publishing Year : 1432 AH
2011 AD 
Article Type : Article 
Added Date : Saturday, April 14, 2012 

Researchers

Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
M C D MouradMourad, M C DResearcherDoctoratem.mourad@ucl.ac.uk
محمد مختارMokhtar, Mohammed ResearcherDoctoratemmokhtar2000@yahoo.com
M G TuckerTucker, M GResearcherDoctorate 
E R BarneyBarney, E RResearcherDoctorate 
R I SmithSmith, R IResearcherDoctorate 
عبدالرحمن عبيد اليوبيAl-Youbia, Abdulrahman ObaidResearcherDoctorateaalyoubi@kau.edu.sa
سليمان ناصر باسهلBasahel, Suliman NaserResearcherDoctoratesbasahel@kau.edu.sa
M S.P ShafferShaffer, M S.PResearcherDoctorate 
N T SkipperSkipper, N TResearcherDoctoraten.skipper@ucl.ac.uk

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