Spin Frustration in 2D Kagomé Lattices: A Problem for Inorganic Synthetic Chemistry

Nocera, Daniel G.; Bartlett, Bart M.; Grohol, Daniel; Papoutsakis, Dimitris; Shores, Matthew P.

doi:10.1002/chem.200306074

Cited by 134 publications

(121 citation statements)

References 52 publications

(61 reference statements)

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“…The split-type CD signal that we observed in the Soret-band region indicates that the chiral side chains in CCP influence the orientation of the porphyrin plane in 1 to produce an induced-CD (ICD) signal, which should reflect the contrast pattern of the [1·CCP] assemblies. In fact, Figure 4 D represents the HRTEM micrograph of the aligned assemblies constructed from CCP and 1; the kagomØ lattice and triangular grid patterns [21,22] with a 0.8-nm- periodicity dark contrast regions are clearly apparent. The differences between the contrast patterns of CP (lamellar) and CCP (kagomØ lattice) might arise from the orientation of 1 in the assemblies being affected differently by the alkyl chains of CP and CCP.…”

Section: Methodsmentioning

confidence: 99%

A Supramolecular Bundling Approach toward the Alignment of Conjugated Polymers

et al. 2006

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Section: Methodsmentioning

confidence: 99%

A Supramolecular Bundling Approach toward the Alignment of Conjugated Polymers

et al. 2006

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“…Jarosite is thought to exist on Mars, and its presence suggests that water existed on Mars in the past (Klingelhöfer et al 2004;Madden et al 2004;Papike et al 2006aPapike et al , 2006b. The position of Fe 3+ ions in the jarosite structure may be described by a Kagomé lattice, and the magnetic properties have led to additional research in this area (Wills and Harrison 1996;Greedan 2001;Grohol et al 2003;Harrison 2004;Nocera et al 2004; Bartlett and Nocera 2005). The jarosite group is thought to be the principle model for studying spin frustration.…”

Section: Introductionmentioning

confidence: 99%

Crystal chemistry of the natrojarosite-jarosite and natrojarosite-hydronium jarosite solid-solution series: A synthetic study with full Fe site occupancy

Basciano

Peterson

2008

American Mineralogist

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Members of the natrojarosite-hydronium jarosite [(Na,H 3 O)Fe 3 (SO 4 ) 2 (OH) 6 ] and jarosite-natrojarosite [(K,Na)Fe 3 (SO 4 ) 2 (OH) 6 ] solid-solution series were synthesized and investigated by Rietveld analysis of X-ray powder diffraction data. The synthesized samples have full Fe occupancy, where in many previous studies there were significant vacancies in the B site. Well-defined trends can be seen in the unit-cell parameters across the solid-solution series in the synthetic samples. The majority of the samples in this study were directly synthesized under hydrothermal conditions at 140 °C. End-member natrojarosite was synthesized using a two-step method, where the initial sample was heated in a 1.0 m H 2 SO 4 -0.5Na 2 SO 4 solution at 200 °C for 3 days, yielding a sample with 100% Na occupancy. Many of the samples were initially zoned and required grinding and re-heating in the reactant solution for homogenization. Substitution of H 3 O and K into natrojarosite changes unit-cell parameters in a linear fashion. The unit-cell parameters presented here are significantly different than the majority of previous studies on synthetic samples, as samples in the current study have full Fe occupancy and the Na-K jarosite series has no H 3 O substitution in the A site. Substitution in the A site mainly affects unit-cell parameter c with little change in a. As Na occupancy increases there is a decrease in A-O2 and A-O3 distances and a consequent increase in Fe-O2 and Fe-O3 distance leading to an overall decrease in unit-cell parameter c in both the Na-H 3 O and Na-K jarosite series. The synthetic samples are compared to natural samples from mine waste deposits in Rio Tinto (Huelva, Spain), Ely Mine (Vermont), and a mineral collecting locality near Sharbot Lake (Ontario), as well as natural and synthetic samples documented in the literature. Based on unit-cell parameters many of the natural samples appear to have full Fe occupancy and correlate well with the synthetic samples from this study. The infrared spectra of the samples were analyzed, and there is a gradual change in the spectral features across the solid-solution series between end-members. The results from this study will aid in the interpretation of the possible chemical compositions of natural jarosite group minerals in mine waste and on Mars.

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“…Monovalent and divalent metal ions including Pb 2+ , Cd 2+ , and Tl + may be coprecipitated and incorporated in the structure of these minerals, resulting in removal and immobilization of these species from the aqueous environment. Moreover, the magnetic ions in the jarosite structure are located in nodes of a Kagomé lattice and the magnetic properties of these compounds have received much attention (Greedan 2001;Harrison 2004;Nocera et al 2004). In addition, the identifi cation of jarosite on Mars has been taken as evidence for aqueous processes on the planet (Klingelhöfer et al 2004;Madden et al 2004;Squyres et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Characterization of defects and the local structure in natural and synthetic alunite (K, Na, H3O)Al3(SO4)2(OH)6 by multi-nuclear solid-state NMR spectroscopy

Nielsen

Majzlan

Phillips

et al. 2007

American Mineralogist

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The local structural environments in a series of natural and synthetic alunite samples [ideally AAl 3 (SO 4 ) 2 (OH) 6 , A = H 3 O + , D 3 O + , Na + , and K + ] have been probed by solid-state 1 H, 2 H, 23 Na, 27 Al, and 39 K NMR spectroscopy. The natural alunite [KAl 3 (SO 4 ) 2 (OH) 6 ] and synthetic hydronium alunite samples contain few structural defects, whereas the synthetic natroalunite and alunite samples have ca. 10% Al vacancies based on 27 Al NMR. A new 27 Al local environment (Al D ) was observed and assigned to Al with one Al vacancy in the fi rst cation sphere. Three different proton environments, Al 2 -OH, Al-OH 2 , and H 3 O + are detected by 1 H and 2 H MAS NMR. The hydronium ion (H 3 O + ) is only observed in hydronium alunite, and is associated with the stoichiometric regions of the sample. It was not detected in 1 H and 2 H NMR spectra of alunite and natroalunite despite K (Na) occupancies of signifi cantly less than 100%, as determined from elemental analysis. Thus, our NMR results suggest that the common assumption, namely that an A vacancy and an Al 3+ vacancy are compensated by adding an H 3 O + and 3 H + (creating 3 Al-OH 2 groups), respectively, is too simplistic. Instead, a signifi cant fraction of the Al 3+ vacancies are compensated for by 4 H + ions, resulting in 4 Al-OH 2 groups per vacancy. This substitution is accompanied by the simultaneous deprotonation of a H 3 O + ion present on the A site. The resultant H 2 O molecule is unnecessary for charge balance, accounting for the A-site defi ciency often observed. The presence of Al 3+ and A + vacancies appears closely correlated based on NMR.

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Spin Frustration in 2D Kagomé Lattices: A Problem for Inorganic Synthetic Chemistry

Cited by 134 publications

References 52 publications

A Supramolecular Bundling Approach toward the Alignment of Conjugated Polymers

A Supramolecular Bundling Approach toward the Alignment of Conjugated Polymers

Crystal chemistry of the natrojarosite-jarosite and natrojarosite-hydronium jarosite solid-solution series: A synthetic study with full Fe site occupancy

Characterization of defects and the local structure in natural and synthetic alunite (K, Na, H3O)Al3(SO4)2(OH)6 by multi-nuclear solid-state NMR spectroscopy

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