Room- and high-pressure crystal chemistry of CoAs and FeAs

Lyman, P. S.; Prewitt, C. T.

doi:10.1107/s0108768184001695

Cited by 41 publications

(24 citation statements)

References 8 publications

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“…Indeed, the exact crystal symmetry of FeAs is somewhat ambiguous as past single crystal studies have come to different conclusions on whether P na2 1 or P nma is the correct space group. 9,30 A lowering of the crystal symmetry of FeAs, however, may not be necessary in order for Γ 3 and Γ 4 to be degenerate and therefore mix at the magnetic ordering temperature. It is possible that the magnetic symmetry of FeAs is independent from the crystal symmetry, a strategy used by Kallel et al in their calculations of the propagation vectors for FeP, CrAs, and MnP, all of which have the crystal structure of FeAs and show similar modulated magnetism.…”

Section: Discussion and Summarymentioning

confidence: 99%

Noncollinear spin-density-wave antiferromagnetism in FeAs

et al. 2011

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The nature of the magnetism in the simplest iron arsenide is of fundamental importance in understanding the interplay between localized and itinerant magnetism and superconductivity. We present the magnetic structure of the itinerant monoarsenide, FeAs, with the B31 structure. Powder neutron diffraction confirms incommensurate modulated magnetism with wavevector q = (0.395 ± 0.001)c * at 4 K, but cannot distinguish between a simple spiral and a collinear spin-density wave structure. Polarized single crystal diffraction confirms that the structure is best described as a non-collinear spin-density wave arising from a combination of itinerant and localized behavior with spin amplitude along the b-axis direction being (15 ± 5)% larger than in the a-direction. Furthermore, the propagation vector is temperature dependent, and the magnetization near the critical point indicates a two-dimensional Heisenberg system. The magnetic structures of closely related systems are discussed and compared to that of FeAs.

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Section: Discussion and Summarymentioning

confidence: 99%

Noncollinear spin-density-wave antiferromagnetism in FeAs

et al. 2011

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“…Such short distances are nearly absent in sulfides and sulfosalts ). If we take the As-As contacts in synthetic NiAs (Thompson et al, 1988), FeAs (Lyman and Prewitt, 1984) and FeAs 2 (Lutz et al, 1987) as (on average) 3.3 Å, and consider them significant for As 3-, then r(As 3-) is 1.65 Å. With the r(As 3-) assumed from As-As contacts, the derived Cu-As distance of 2.285 Å is at the lower limit of the observed Cu-As distances (although they increase with coordination number).…”

Section: Crystal Structurementioning

confidence: 99%

Crystal structure and chemistry of natural kutinaite from Černý Důl, Krkonoše, Czech Republic

Bindi

Makovicky

2015

Mineral. mag.

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We have characterized the crystal structure of natural kutinaite, a rare mineral from the ores of Černý Důl, Czech Republic, by single-crystal X-ray diffraction and chemical analysis. We found that the structure of natural kutinaite is not identical to that of synthetic Cu14Ag6As7, previously reported to be cubic, space group Pm3m. Although topologically similar, the structure of natural kutinaite is indeed tetragonal, space group P4/mmm, with cell parameters: a = 11.789(2), c = 11.766(2) Å, V = 1635.5(4) Å3 and Z = 4. Electron microprobe analyses pointed to the (K,Tl)0.25Cu14Ag6As6.75 stoichiometry (Z = 4), or (K, Tl)Cu56Ag24As27 with Z = 16. The crystal structure of an untwinned crystal has been refined to R1 = 2.61%. It consists of clusters of eight edge-sharing tetrahedra of Cu, which alternate in a 3D chess-board manner with octahedral clusters of six Ag atoms. The latter are surrounded by triangularly coordinated copper in eight faces of a cuboctahedron. The last structure components are large cavities containing partly occupied (K,Tl) sites, coordinated by 18 Ag and As ligands. The structure is full of direct metal-metal contacts although As plays the role of anion, associating especially with copper.

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“…Therefore, it is natural to inspect the properties of iron monoarsenide (FeAs)-type materials, which are supposed to provide useful information for the paring mechanism in iron-based superconductors, concerning its relatively simple constitution. However, even though the FeAs single crystal has been known for decades, no superconducting evidences are hitherto discovered in this compound [5][6][7][8][9][10] . Distinct from the so-called "11" type superconductor FeSe 11,12 or the FeAs layers in other iron-based superconductors, FeAs compound crystalizes in a MnP-type orthorhombic structure 13 and shows double-helical magnetic structure at low temperatures 14,15 , which makes it irrelevant to iron-based superconductors.…”

Section: Introductionmentioning

confidence: 99%

Optical study of phase transitions in single-crystalline RuP

et al. 2015

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RuP single crystals of MnP-type orthorhombic structure were synthesized by the Sn flux method. Temperature-dependent x-ray diffraction measurements reveal that the compound experiences two structural phase transitions, which are further confirmed by enormous anomalies shown in temperature-dependent resistivity and magnetic susceptibility. Particularly, the resistivity drops monotonically upon temperature cooling below the second transition, indicating that the material shows metallic behavior, in sharp contrast with the insulating ground state of polycrystalline samples. Optical conductivity measurements were also performed in order to unravel the mechanism of these two transitions. The measurement revealed a sudden reconstruction of band structure over a broad energy scale and a significant removal of conducting carriers below the first phase transition, while a charge-density-wave-like energy gap opens below the second phase transition.

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Room- and high-pressure crystal chemistry of CoAs and FeAs

Cited by 41 publications

References 8 publications

Noncollinear spin-density-wave antiferromagnetism in FeAs

Noncollinear spin-density-wave antiferromagnetism in FeAs

Crystal structure and chemistry of natural kutinaite from Černý Důl, Krkonoše, Czech Republic

Optical study of phase transitions in single-crystalline RuP

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