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Nomenclature of the hydrotalcite supergroup: natural layered double hydroxides

Mills, S J; Christy, Andrew; Genin , J. M. R.; Kameda, T.; Colombo, Fernando

Description

Layered double hydroxide (LDH) compounds are characterized by structures in which layers with a brucite-like structure carry a net positive charge, usually due to the partial substitution of trivalent octahedrally coordinated cations for divalent cations, giving a general layer formula [( M 2+1-x M 3+x )(OH)2] x+. This positive charge is balanced by anions which are intercalated between the layers. Intercalated molecular water typically provides hydrogen bonding between the brucite layers. In...[Show more]

dc.contributor.authorMills, S J
dc.contributor.authorChristy, Andrew
dc.contributor.authorGenin , J. M. R.
dc.contributor.authorKameda, T.
dc.contributor.authorColombo, Fernando
dc.date.accessioned2015-12-13T22:22:19Z
dc.identifier.issn0026-461X
dc.identifier.urihttp://hdl.handle.net/1885/72195
dc.description.abstractLayered double hydroxide (LDH) compounds are characterized by structures in which layers with a brucite-like structure carry a net positive charge, usually due to the partial substitution of trivalent octahedrally coordinated cations for divalent cations, giving a general layer formula [( M 2+1-x M 3+x )(OH)2] x+. This positive charge is balanced by anions which are intercalated between the layers. Intercalated molecular water typically provides hydrogen bonding between the brucite layers. In addition to synthetic compounds, some of which have significant industrial applications, more than 40 mineral species conform to this description. Hydrotalcite, Mg6Al2(OH) 16[CO3]•4H2O, as the longest-known example, is the archetype of this supergroup of minerals. We review the history, chemistry, crystal structure, polytypic variation and status of all hydrotalcite-supergroup species reported to date. The dominant divalent cations, M 2+, that have been reported in hydrotalcite supergroup minerals are Mg, Ca, Mn, Fe, Ni, Cu and Zn; the dominant trivalent cations, M 3+, are Al, Mn, Fe, Co and Ni. The most common intercalated anions are (CO3)2-, (SO4)2- and Cl -; and OH-, S2- and [Sb(OH)6] - have also been reported. Some species contain intercalated cationic or neutral complexes such as [Na(H2O)6]+ or [MgSO4]0. We define eight groups within the supergroup on the basis of a combination of criteria. These are (1) the hydrotalcite group, with M 2+:M 3+ = 3:1 (layer spacing ∼7.8 Å); (2) the quintinite group, with M 2+:M 3+ = 2:1 (layer spacing ∼7.8 Å); (3) the fougèrite group, with M 2+ = Fe2+, M 3+ = Fe3+ in a range of ratios, and with O2- replacing OH- in the brucite module to maintain charge balance (layer spacing ∼7.8 Å); (4) the woodwardite group, with variable M 2+:M 3+ and interlayer [SO4] 2-, leading to an expanded layer spacing of ∼8.9 Å; (5) the cualstibite group, with interlayer [Sb(OH)6]- and a layer spacing of ∼9.7 Å; (6) the glaucocerinite group, with interlayer [SO4]2- as in the woodwardite group, and with additional interlayer H2O molecules that further expand the layer spacing to ∼11 Å; (7) the wermlandite group, with a layer spacing of ∼11 Å, in which cationic complexes occur with anions between the brucite-like layers; and (8) the hydrocalumite group, with M 2+ = Ca2+ and M 3+ = Al, which contains brucite-like layers in which the Ca:Al ratio is 2:1 and the large cation, Ca2+, is coordinated to a seventh ligand of 'interlayer' water. The principal mineral status changes are as follows. (1) The names manasseite, sjögrenite and barbertonite are discredited; these minerals are the 2H polytypes of hydrotalcite, pyroaurite and stichtite, respectively. Cyanophyllite is discredited as it is the 1M polytype of cualstibite. (2) The mineral formerly described as fougèrite has been found to be an intimate intergrowth of two phases with distinct Fe 2+:Fe3+ ratios. The phase with Fe2+:Fe 3+ = 2:1 retains the name fougèrite; that with Fe 2+:Fe3+ = 1:2 is defined as the new species trébeurdenite. (3) The new minerals omsite (IMA2012-025), Ni 2Fe3+(OH)6[Sb(OH)6], and mössbauerite (IMA2012-049), Fe3+6O 4(OH)8[CO3]•3H2O, which are both in the hydrotalcite supergroup are included in the discussion. (4) Jamborite, carrboydite, zincaluminite, motukoreaite, natroglaucocerinite, brugnatellite and muskoxite are identified as questionable species which need further investigation in order to verify their structure and composition. (5) The ranges of compositions currently ascribed to motukoreaite and muskoxite may each represent more than one species. The same applies to the approved species hydrowoodwardite and hydrocalumite. (6) Several unnamed minerals have been reported which are likely to represent additional species within the supergroup. This report has been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association, voting proposal 12-B. We also propose a compact notation for identifying synthetic LDH phases, for use by chemists as a preferred alternative to the current widespread misuse of mineral names.
dc.publisherMineralogical Society (UK)
dc.sourceMineralogical Magazine
dc.subjectKeywords: barbertonite; Brucite; cyanophyllite; Hydrotalcites; Layered double hydroxides; LDH; manasseite; Aluminum; Antimony; Calcium; Carbonate minerals; Chlorine; Coordination reactions; Hydrogen bonds; Industrial applications; Manganese; Terminology; Positive i barbertonite; brucite; cyanophyllite; fougèrite; hydrotalcite; hydrotalcite supergroup; layered double hydroxide; LDH; manasseite; nomenclature; sjögrenite; trébeurdenite
dc.titleNomenclature of the hydrotalcite supergroup: natural layered double hydroxides
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume76
dc.date.issued2012
local.identifier.absfor040300 - GEOLOGY
local.identifier.absfor040200 - GEOCHEMISTRY
local.identifier.ariespublicationf5625xPUB3110
local.type.statusPublished Version
local.contributor.affiliationMills, S J, Museum Victoria
local.contributor.affiliationChristy, Andrew, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationGenin , J. M. R., CNRS-Universite de Lorraine
local.contributor.affiliationKameda, T., Tohoku University
local.contributor.affiliationColombo, Fernando, Universidad Nacional de Cordoba
local.description.embargo2037-12-31
local.bibliographicCitation.issue5
local.bibliographicCitation.startpage1289
local.bibliographicCitation.lastpage1336
local.identifier.doi10.1180/minmag.2012.076.5.10
dc.date.updated2016-02-24T09:05:44Z
local.identifier.scopusID2-s2.0-84869168467
local.identifier.thomsonID000311015800013
CollectionsANU Research Publications

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