Structure and stability of aluminium trihydroxides bayerite and gibbsite: A quantum mechanical ab initio study with the Crystal06 code

Abstract

a b s t r a c tThe structure and energetics of bayerite and gibbsite have been investigated at the periodic ab-initio quantum-mechanical level by using a Gaussian type basis set and the B3LYP Hamiltonian.Both systems have layered structure, with intra-layer and inter-layer hydrogen bonds (HBs). In gibbsite the latter are stronger than in bayerite: 23.15 and 17.59 kJ/mol, respectively. The formation Gibbs free energy has been calculated, including entropic and enthalpic contributions: at 298 K gibbsite is more stable than bayerite by 7.74 kJ/mol.

Coordination nature of aluminum (oxy)hydroxides formed under the influence of low molecular weight organic acids and a soil humic acid studied by X-ray absorption spectroscopy

“…The gibbsite formed in this system was different from that formed in the absence of LMW organic acids as the ratio of the 4.37/4.83 Å peaks was reversed. The difference between bayerite and gibbsite is due to the different stacking of the oxygen layers and the orientation of the O-H bonds (Demichelis et al, 2008). Evidently, malic acid induced the stacking of the sheets to change.…”

“…One of the mechanisms by which the sheets link together is through protonated Al-O bonds that participate in extensive hydrogen bonding. Gibbsite and bayerite form layers that are linked together by inter-layer H-bonds (Demichelis et al, 2008). Pseudoboehmite also forms layers, with the inter-layers filled with water molecules that form H-bonds between the layers (Moroz et al, 2006).…”

Performance of 12 DFT functionals in the study of crystal systems: Al2SiO5 orthosilicates and Al hydroxides as a case study

“…Al hydroxides can be distinguished in mono-hydroxides (i.e., diaspore/boehmite) and tri-hydroxides (i.e., gibbsite/bayerite) The relative stability is then: Diaspore>boehmite and gibbsite>bayerite [80,86], respectively. However, the absolute value of their relative stability, is still a matter of investigation [37,41,44,[78][79][80][81]86], with the uncertainty being often of the order of G itself.…”

“…Furthermore, many properties of aluminium hydroxides still remain a matter of discussion [14,36,37], with open questions related to structural, vibrational, and energetics. Although, some of them were successfully tackled in previous works [14,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. In addition, to confirm the assessment of the performance of DFT methods for H-containing systems, brucite (Mg(OH) 2 ) is also included as an example of layered material, where hydrogen is not involved in hydrogen bonds (HB).…”

DFT Study of Polymorphism in Al(OH)3: A Structural Synthon Approach

“…[21,[23][24][25][26][27][28] While some of these studies with an emphasis on computing the total energy are aimed at predicting the relative stabilities of the four polymorphs, [21,29,30] others given the unique structural complexities of Al(OH) 3 use it as a model system to validate new approaches to electronic structure calculations. [23] In this paper, an Al(OH) 3 layer derived from bayerite is used as a structural synthon and the energy profile of structures aris-www.zaac.wiley-vch.de ARTICLE ing out of the translation of two adjacent Al(OH) 3 layers is computed relative to one another.…”