Fe^II₂(PO₄)(OH), a synthetic analogue of wolfeite

Abstract

This paper reports the hydrothermal synthesis and crystal structure refinement of diiron(II) phosphate hydroxide, Fe(II)2(PO4)(OH), obtained at 1063 K and 2.5 GPa. This phosphate is the synthetic analogue of the mineral wolfeite, and has a crystal structure topologically identical to those of minerals of the triplite-triploidite group. The complex framework contains edge- and corner-sharing FeO4(OH) and FeO4(OH)2 polyhedra, linked via corner-sharing to the PO4 tetrahedra (average P-O distances are between 1.537 and 1.544 A). Four five-coordinated Fe sites are at the centers of distorted trigonal bipyramids (average Fe-O distances are between 2.070 and 2.105 A), whereas the coordination environments of the remaining Fe sites are distorted octahedra (average Fe-O distances are between 2.146 and 2.180 A). The Fe-O distances are similar to those observed in natural Mg-rich wolfeite, except for two Fe-O bond distances, which are significantly longer in synthetic Fe(2+)2(PO4)(OH).

Superspace description of wagnerite-group minerals (Mg,Fe,Mn)2(PO4)(F,OH)

“…The structure of the (2b) type with the P2 1 /n space group is represented by three end-members: Mg 2 (PO 4 )F (this paper), Mg 2 (PO 4 )OH (Raade & Rømming, 1986) and Fe 2 (PO 4 )OH (Hatert, 2007) and minerals with intermediate composition, such as wagnerite (Mg, Fe) 2 (PO 4 )F (Coda et al, 1967), hydroxylwagnerite (Mg, Fe) 2 (PO 4 )OH (Brunet et al, 1998;Chopin et al, 2004), triploidite Mn 1.5 Fe 0.5 (PO 4 )OH (Waldrop, Table 1 Synthetic and natural end-members, with unit-cell dimensions in unified setting.…”

Synthesis, Structures, and Magnetic Investigations of Nickel Phosphates: Ni2(PO4)(OH), Ni7(PO4)3(HPO4)(OH)3, and NaNiPO4 Including Potential Haldane Behavior

“…Spin-glass behavior was observed at low temperatures in γ-Co 2 (PO 4 )­(OH) . The other M 2 (PO 4 )­(OH) and M 2 (AsO 4 )­(OH) analogs reported in the structural literature appear to be confined to the orthorhombic and tetragonal polymorphs. − The difficulty in isolating purely nickel-based analogs of these compounds has been documented elsewhere, so their synthesis as reasonably large-sized single crystals from high-temperature hydrothermal reactions is particularly fortuitous.…”

Composition and morphology control of Fex(PO4)y(OH)z·nH2O microcrystals

“…Iron hydroxyl phosphates (Fe x (PO 4 ) y (OH) z ·nH 2 O) [9,11], such as barbosalite Fe 3 (PO 4 ) 2 (OH) 2 [12,14], rockbridgeite Fe 5 (PO 4 ) 3 (OH) 5 [15,16], beraunite Fe 6 (PO 4 ) 4 (OH) 5 ·6H 2 O [17,18], and whitmoreite Fe 3 (PO 4 ) 2 (OH) 2 ·4H 2 O [19], are well-known minerals and important catalysts for oxidative dehydrogenation reactions [20,21]. They are significant in corrosion inhibition, passivation of metal surfaces [22], and also important in various considerations of the reactions of iron compounds contained in various soils with phosphate fertilizers [23].…”