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Lipin, Vadim A.

doi:10.1023/a:1012749428765

Cited by 7 publications

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“…Al(OH) 3 has a layered structure, in which a third of the cationic sites are vacant [1][2][3][4]. The layer composition is [Al 2 (OH) 6 ] ( : cation vacancy).…”

Section: Introductionmentioning

confidence: 99%

Reversible hydration of the perchlorate-intercalated layered double hydroxides of Li and Al: structure models for the dehydrated phases

Pachayappan

Kamath

2020

Bull Mater Sci

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Imbibition of lithium sulphate into aluminium hydroxide is known to result in a sulphate-intercalated layered double hydroxide (LDH) of Li and Al. The perchlorate ion has the same size and molecular symmetry as the sulphate ion, but only half its charge. Consequently, twice the number of ClO − 4 ions is needed to balance LDHs the charge on the metal hydroxide layer, compared to the SO 2− 4 ions. In this work, the ClO − 4 -intercalated LDHs were obtained from both the bayerite and gibbsite precursors. Inclusion of the hydration sphere along with the ClO − 4 anion, induced turbostratic disorder in the stacking of the metal hydroxide layers. Temperature-induced dehydration (T ∼ 100-140 • C) brought about a partial ordering in the interlayer region and the ClO − 4 ion oriented itself with one of its C 2 -axes parallel to the metal hydroxide layer. The close packing of ClO − 4 ions could be realized by the complete dehydration of LDH and the distribution of the ClO − 4 ions in all the available interlayer sites. In contrast, within the crystal of the sulphate analogue, the sulphate ions occupy only half the number of interlayer sites. The other half is occupied by the residual water molecules, as the sulphate analogue does not fully dehydrate even at elevated temperatures. This difference in the behaviour of the two LDHs has its origin in the large difference in the hydration enthalpies of the two anions.

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“…Al(OH) 3 has a layered structure, in which a third of the cationic sites are vacant [1][2][3][4]. The layer composition is [Al 2 (OH) 6 ] ( : cation vacancy).…”

Section: Introductionmentioning

confidence: 99%

Reversible hydration of the perchlorate-intercalated layered double hydroxides of Li and Al: structure models for the dehydrated phases

Pachayappan

Kamath

2020

Bull Mater Sci

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“…As different polytypes are expected to have different properties, the synthesis and characterization of different polytypic modifications is of interest to the fields of catalysis, ion exchange and sorption. [9,10] While this approach has been applied with great success to the layer groups p32/m1 [5] and p312/m, [3,4] wherein the principal axis of rotation is parallel to the stacking direction, the question arises as to how to extend this approach to layers of low symmetry. The complete universe of possible stacking sequences of layers belonging to the layer groups such as p1, p1, p12 1 1 or p12 1 /a1 cannot be intuitively envisaged and requires a computational approach.…”

Section: Introductionmentioning

confidence: 99%

“…Gibbsite is formed at pH 5, [11] bayerite at pH 9-11, [12] nordstrandite by carbonization of aluminate solution. [10] There are no reports of the laboratory synthesis of doyleite. Of these, gibbsite is thermodynamically most stable and is abundantly found in nature, and bayerite, although relatively less abundant, can be easily synthesized in the laboratory.…”

Section: Introductionmentioning

confidence: 99%

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

Nagendran

Periyasamy

Kamath

2015

Zeitschrift anorg allge chemie

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Abstract. All the known polymorphs of Al(OH) 3 comprise a stacking of charge neutral layers having the composition [Al 2/3 ᮀ 1/3 (OH) 2 ] (ᮀ: cation vacancy) and designated by the symbol P. Employing a single Al(OH) 3 layer (layer group p12 1 /a1) as a structural synthon, the energy profile computed for the translations of P and P (P: mirror image of P) layers relative to each other within a bilayer model, not only show minima corresponding to the four known polymorphs of Al(OH) 3 but also predict three new polymorphs with energy minima at the stacking

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“…Pure nordstrandite microcrystals have been synthesised by ageing non-crystalline aluminium hydroxide in an aqueous medium in the presence of ethylenediamine [19], or ethylene glycol [18], or sodium aluminate solution [20].…”

Section: Introductionmentioning

confidence: 99%

Crystallization of nordstrandite in ethylene glycol / water solutions: electron microscopic studies

Antunes

Santos

2009

Open Chemistry

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The present work shows the growth of nordstrandite microcrystals observed by transmission and scanning electron microscopy.Nordstrandite was synthesised from non-crystalline aluminium hydroxide reacted in 20% ethylene glycol/water solution, at room temperature. This material was characterized by TEM, SEM, SAED, XRD and EDS/TEM, during six month and revealed the formation and growth of nordstrandite. Fibrillar pseudoboehmite is the only aluminium hydroxide which could be identified during the first two weeks. The nuclei grow, from complete dissolution/recrystallization of pseudoboehmite fibrils, into platy rectangular microscrystals of nordstrandite. Some tabular microcrystals recrystallise, forming after six months only the multi-point nordstrandite stars. This electron-optical study suggest that the star shape results from the overlapping of rectangular plates, and pseudoboehmite fibrils act as the precursor of nordstrandite crystallisation in ethylene glycol/water solution.

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Cited by 7 publications

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Reversible hydration of the perchlorate-intercalated layered double hydroxides of Li and Al: structure models for the dehydrated phases

Reversible hydration of the perchlorate-intercalated layered double hydroxides of Li and Al: structure models for the dehydrated phases

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

Crystallization of nordstrandite in ethylene glycol / water solutions: electron microscopic studies

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Untitled

Cited by 7 publications

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Reversible hydration of the perchlorate-intercalated layered double hydroxides of Li and Al: structure models for the dehydrated phases

Reversible hydration of the perchlorate-intercalated layered double hydroxides of Li and Al: structure models for the dehydrated phases

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

Crystallization of nordstrandite in ethylene glycol / water solutions: electron microscopic studies

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