Structure of the Carbonate-Intercalated Layered Double Hydroxides: A Reappraisal

Marappa, Shivanna; Kamath, P. Vishnu

doi:10.1021/acs.iecr.5b03207

Cited by 26 publications

(35 citation statements)

References 34 publications

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“…Despite the general viewpoint that the 3 R polytype is the most common for hydrotalcite-supergroup minerals, crystal-structure studies of members that combine the M 2+ : M 3+ ratio of 2:1 and a rhombohedral stacking sequence indicate a high tendency for the M 2+ and M 3+ cations to form × superstructures within brucite-type layers that results in a monoclinic symmetry (Table 2) due to the disappearance of threefold axes (synthetic LDHs with Li:Al = 1:2 [Sissoko et al ., 1985; Britto et al ., 2008; Britto and Kamath, 2009], quintinite-1 M [Krivovichev et al ., 2010 b , 2012 a , Zhitova et al ., 2016 c ; Jayanthi et al ., 2015]; synthetic LDHs with Zn:Al = 2:1 [Marappa and Kamath, 2015]). It is important to emphasize that a ‘classic’ 3 R polytype was found for a quintinite sample with a very high content of Fe 2+ .…”

Section: Discussionmentioning

confidence: 99%

“…We note that the structural model of the 1 M polytype proposed by us for quintinite-1 M was used by Jayanthi et al . (2015) for synthetic LDHs and applied for the Rietveld structure refinement of the synthetic analogue of zaccagnaite, [Zn 4 Al 2 (OH) 12 ][(CO 3 )(H 2 O) 3 ] (Marappa and Kamath, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…Previously published structural models of quintinite appeared to be helpful for the characterization of hydrotalcite-supergroup members (Lozano et al ., 2012; Mills et al ., 2012 a ; Theiss et al ., 2015); synthetic layered double hydroxides (Zhang and Evans, 2012; Jayanthi and Kamath, 2013, 2016; Radha et al ., 2014; Jayanthi et al ., 2015; Marappa and Kamath, 2015); their crystal structure simulation and analysis (Radha and Kamath, 2012; Richardson, 2013; Ghamami et al ., 2016; Tsukanov and Psakhie, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Crystal chemistry of natural layered double hydroxides: 4. Crystal structures and evolution of structural complexity of quintinite polytypes from the Kovdor alkaline-ultrabasic massif, Kola peninsula, Russia

et al. 2018

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Two quintinite polytypes, 3R and 2T, which are new for the Kovdor alkaline-ultrabasic complex, have been structurally characterized. The crystal structure of quintinite-2T was solved by direct methods and refined to R1 = 0.048 on the basis of 330 unique reflections. The structure is trigonal, P$\bar 3$c1, a = 5.2720(6), c = 15.113(3) Å and V = 363.76(8) Å3. The crystal structure consists of [Mg2Al(OH)6]+ brucite-type layers with an ordered distribution of Mg2+ and Al3+ cations according to the $\sqrt 3 $ × $\sqrt 3 $ superstructure with the layers stacked according to a hexagonal type. The complete layer stacking sequence can be described as …=Ab1C = Cb1A=…. The crystal structure of quintinite-3R was solved by direct methods and refined to R1 = 0.022 on the basis of 140 unique reflections. It is trigonal, R$\bar 3$m, a = 3.063(1), c = 22.674(9) Å and V = 184.2(1) Å3. The crystal structure is based upon double hydroxide layers [M2+,3+(OH)2] with disordered distribution of Mg, Al and Fe and with the layers stacked according to a rhombohedral type. The stacking sequence of layers can be expressed as …=АB = BC = CA=… The study of morphologically different quintinite generations grown on one another detected the following natural sequence of polytype formation: 2H → 2T → 1M that can be attributed to a decrease of temperature during crystallization. According to the information-based approach to structural complexity, this sequence corresponds to the increasing structural information per atom (IG): 1.522 → 1.706 → 2.440 bits, respectively. As the IG value contributes negatively to the configurational entropy of crystalline solids, the evolution of polytypic modifications during crystallization corresponds to the decreasing configurational entropy. This is in agreement with the general principle that decreasing temperature corresponds to the appearance of more complex structures.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Crystal chemistry of natural layered double hydroxides: 4. Crystal structures and evolution of structural complexity of quintinite polytypes from the Kovdor alkaline-ultrabasic massif, Kola peninsula, Russia

et al. 2018

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“…Also the lattice constant "a" results in a linear combination of ionic radii and molar fraction x. Nevertheless, some local cations order has been documented, and some authors have highlighted longrange cation ordering of organized superstructures [4,9,10]. Anyway results are still controversial.…”

Section: +mentioning

confidence: 99%

Characteristics, Preparation Routes and Metallurgical Applications of LDHs: An Overview

Richetta¹

2017

J Material Sci Eng

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The peculiar properties of layered Double Hydroxides (LDH) have progressively drawn the attention of the scientific community. The main characteristic of LDH is the ability to capture anionic species (organic and inorganic) to build different composites. This is made possible by the sandwich structure of the LDH, similar to the brucite architecture, made up of positive charged lamellas interspersed by anions. Several distant fields, ranging from medicine to physics and engineering, exhibit interest in LDH applications. To satisfy all those requirements, energy was spent to sculpt LDHs physical and chemical properties and for designing layered double hydroxides "ad hoc" for different needs and employments. Notably, among the many applications, those related to metallurgical processes and products are of particular interest. This paper presents the characteristics, the main preparation routes and reviews the applications of LDH to metallurgy with some examples taken from the experimental research of the author.

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“…The important characteristics of LDHs is that these moieties are generally weakly bound to the host lamellas and can therefore either be located during the 3D structure formation or be inserted by subsequent substitution trough anionic exchange [10]. The anions can be grouped as follows:…”

Section: Intercalated Anionsmentioning

confidence: 99%

Layered Double Hydroxides: Tailoring Interlamellar Nanospace for a Vast Field of Applications

Richetta¹,

Medaglia²,

Mattoccia³

et al. 2017

J Material Sci Eng

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Fifty-eight years ago Fenman, during an American Physical Society meeting at the California Institute of Technology, anticipated the problem of modifying and governing the world of the infinitely small. what is possible in principle… We are not doing it simply because we haven't yet gotten around to it." Useless to say how profound his sensibility for science was. We've just begun to walk in this enormous field, toward the assembly of devices atom by atom. What we did till now is still rudimentary. Anyhow we believe that Layered Double Hydroxides could play a role in manufacturing these nanometric equipments.Layered Double Hydroxides (LDHs) are 2D ionic lamellar nano-materials belonging to the group of anionic clays. Their structure consists of positively charged brucite-like layers and intercalated anions. The layered structure, together with the flexibility to intercept different anionic species in variable compositions, both inorganic and organic, has attracted increasing interest. In order to meet specific requirements in very distant fields, considerable efforts were made to tailor the physical/chemical properties of LDHs and to design engineered LDH for several applications, ranging from anticorrosion coatings, flame-retardants, catalysis, to water treatment/purification, and biomedical applications. Furthermore they have been applied in energy harvesting and conversion, thanks to the possibility of substituting the composing metals with transition metals.Within the framework of this contribution, we first briefly review the development of synthesis processes ( §1). In Paragraph 2, examples of the LDHs applications are reported. We will than focus on our laboratory experimental activities, showing the growth of the structures either on printed circuit tracks for applications of LDHs as gas sensors and biosensors. One more application is in nanostructured-modified textiles.

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Structure of the Carbonate-Intercalated Layered Double Hydroxides: A Reappraisal

Cited by 26 publications

References 34 publications

Crystal chemistry of natural layered double hydroxides: 4. Crystal structures and evolution of structural complexity of quintinite polytypes from the Kovdor alkaline-ultrabasic massif, Kola peninsula, Russia

Crystal chemistry of natural layered double hydroxides: 4. Crystal structures and evolution of structural complexity of quintinite polytypes from the Kovdor alkaline-ultrabasic massif, Kola peninsula, Russia

Characteristics, Preparation Routes and Metallurgical Applications of LDHs: An Overview

Layered Double Hydroxides: Tailoring Interlamellar Nanospace for a Vast Field of Applications

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