Long-Range Magnetic Ordering in Iron Jarosites Prepared by Redox-Based Hydrothermal Methods

Abstract

The iron jarosites, plumbojarosite, Pb0.5Fe3(OH)6(SO4)2, argentojarosite, AgFe3(OH)6(SO4)2, and thallium jarosite, TlFe3(OH)6(SO4)2, along with the selenate-capped jarosite analogues of potassium, KFe3(OH)6(SeO4)2, and rubidium, RbFe3(OH)6(SeO4)2, have been prepared in their analytically pure forms by employing redox-based hydrothermal methods. The crystal structures of these materials have been determined, and all are found to be essentially isostructrual including Pb0.5Fe3(OH)6(SO4)2, which is distinct from the structure reported for naturally mined samples. All iron jarosites show long-range order (LRO), signified by a sharp transition temperature, T(N), which falls in the narrow temperature range of 61.4 +/- 5 K. The mechanism responsible for this ordering has been established by examining magnetostructural correlations for the jarosites possessing various interlayer cation and capping groups. We show that all magnetic properties of jarosites, including LRO, find their origin in the basic magnetic unit, the intralayer Fe3(mu-OH)3 triangle. Field-dependent magnetization experiments are consistent with the antiferromagnetic stacking of an out of plane moment developed from spin canting within Fe3(mu-OH)3 triangles. Together with the previously reported AFe3(OH)6(SO4)2 (A = Na+, K+, Rb+ and NH4+) jarosites, these compounds provide a framework for probing magnetic ordering in a spin frustrated lattice of the largest series of isoelectronic and isostructural kagomé systems yet discovered.

Dzyaloshinskii-Moriya interaction and spin reorientation transition in the frustrated kagome lattice antiferromagnet

“…Most notably, we observe a prominent antiferromagnetic ordering temperature T N narrowly ranging from 56-65 K for jarosites with different interplanar cations. 27,28 In addition, the nearest-neighbor exchange interaction is consistent for all jarosites, indicated by similar values of the Curie-Weiss temperature of ∼ −800 K. This similarity in the Curie-Weiss temperature is not surprising, as the basic magnetic unit, the Fe III 3 (µ-OH) 3 triangle, is structurally homologous in all jarosites. Due to frustration and low dimensionality, ground states of a Heisenberg kagome lattice antiferromagnet are infinitely degenerate.…”

Coffinite, USiO4, Is Abundant in Nature: So Why Is It So Difficult To Synthesize?

“…Many routes could be explored such as redox-based hydrothermal methods as reported by Nocera et al in the case of Jarosites. 74,75 ■ ASSOCIATED CONTENT * S Supporting Information UV spectra of a UCl 4 stock solution, coffinite gel, its suspension, and that of a UO 2 (NO 3 ) 2 stock solution ( Figure S1), refined unit cell parameters for USiO 4 and UO 2 (Table S1), thermodynamic data for the main reactions involving U and Si in the considered system (Table S2), and best fit metrical parameters obtained from the EXAFS data of USiO 4 and UO 2 /SiO 2 samples (Table S3). The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/ic502808n.…”

Potential applications of metal-organic frameworks

“…The magnetic frustrations are usually observed in triangular or tetrahedral "plaquette" magnetic lattices [134][135][136]. Gao et al [137] recently reported a Mn 2+ complex, Mn[Mn 3 ( 3 -F)(bta) 3 (H 2 O) 6 ] 2 which has a 2D frustrated lattice with alternating triangular motifs and mononuclear centers.…”