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arxiv: 2208.04209 · v1 · submitted 2022-08-08 · ❄️ cond-mat.str-el

Hydrothermal synthesis of ordered corkite, PbFe3(PO4)(SO4)(OH)6, a S = 5/2 kagom\'e antiferromagnet

Austin M. Ferrenti , Vanessa Meschke , Shreenanda Ghosh , Jackson Davis , Natalia Drichko , Eric S. Toberer , Tyrel M. McQueen This is my paper

Pith reviewed 2026-05-24 10:44 UTC · model grok-4.3

classification ❄️ cond-mat.str-el
keywords corkitejarositekagome antiferromagnethydrothermal synthesismagnetic frustrationFe3+ spin systemantiferromagnetic orderingpolyanion ordering
0
0 comments X

The pith

Synthetic corkite orders antiferromagnetically below 48 K, lower than jarosite phases, due to added frustration from phosphate substitution on the kagomé lattice.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper reports the hydrothermal synthesis of corkite, PbFe3(PO4)(SO4)(OH)6, and its first magnetic characterization. Synthetic samples show infrared and Raman signatures of a more ordered polyanion arrangement that preserves inversion symmetry. Susceptibility data reveal antiferromagnetic ordering at TN = 48 K with a Curie-Weiss temperature of -526 K and an effective moment consistent with high-spin Fe3+. The substitution of phosphate for one sulfate group per formula unit increases steric and electronic pressure on the kagomé network relative to pure jarosites, lowering the ordering temperature and enhancing spin frustration in this S = 5/2 system.

Core claim

Corkite undergoes a transition to a long-range antiferromagnetically ordered state below TN = 48 K. This temperature is lower than in the majority of jarosite phases and signals further spin frustration. The replacement of one sulfate group per formula unit with a higher-valent phosphate group applies additional steric and electronic pressure on the kagomé lattice, further frustrating the magnetic ground state.

What carries the argument

The kagomé sublattice of Fe3+ (S = 5/2) ions formed by the ordered arrangement of mixed PO4 and SO4 polyanions that retains inversion symmetry.

If this is right

  • The magnetic entropy change from 0 K to 195 K reaches 14.86 J/mol Fe3+ K, matching the value expected for an S = 5/2 system.
  • The effective moment of 6.29 muB per Fe3+ and theta_CW of -526 K confirm strong antiferromagnetic coupling typical of high-spin Fe3+ kagomé systems.
  • Corkite acts as an outlier within the jarosite family, demonstrating that targeted anion substitution can strain the lattice and tune the degree of frustration.
  • The material illustrates a route to enhance frustration in existing kagomé structures without changing the magnetic ion.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Similar anion substitutions could be applied to other jarosite or kagomé compounds to systematically lower ordering temperatures and increase frustration.
  • Single-crystal studies of synthetic corkite would allow direct mapping of the magnetic structure and exchange pathways altered by the phosphate group.
  • The retention of inversion symmetry in the ordered polyanion arrangement may suppress certain spin-liquid candidates that require broken symmetry.

Load-bearing premise

That the observed IR and Raman signatures confirm a more ordered polyanion arrangement retaining inversion symmetry, and that this ordering is what lowers TN and increases frustration rather than impurities or defects.

What would settle it

A magnetic susceptibility measurement on a corkite sample whose IR/Raman spectra show disordered polyanions, or on a phosphate-free jarosite analog prepared by the same route, that yields TN comparable to standard jarosites.

Figures

Figures reproduced from arXiv: 2208.04209 by Austin M. Ferrenti, Eric S. Toberer, Jackson Davis, Natalia Drichko, Shreenanda Ghosh, Tyrel M. McQueen, Vanessa Meschke.

Figure 1
Figure 1. Figure 1: Crystal structure of corkite projected a) along the [PITH_FULL_IMAGE:figures/full_fig_p018_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: a) Infrared spectra of representative undried (red) and dried (blue) synthetic corkite [PITH_FULL_IMAGE:figures/full_fig_p021_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Thermogravimetric analysis (black) and differential thermal analysis data (red) as [PITH_FULL_IMAGE:figures/full_fig_p022_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Temperature-dependent magnetic (black) and inverse magnetic (pink) suscepti [PITH_FULL_IMAGE:figures/full_fig_p023_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: a) Heat capacity divided by temperature as a function of temperature, C [PITH_FULL_IMAGE:figures/full_fig_p024_5.png] view at source ↗
read the original abstract

Corkite, PbFe3(PO4)(SO4)(OH)6, an understudied relative of the jarosite family of Heisenberg antiferromagnets, has been synthesized and its magnetic properties characterized for the first time. Relative to natural samples, synthetic corkite displays signatures in both infrared and Raman spectra of a more ordered arrangement of polyanion groups about the kagom\'e sublattice that retains inversion symmetry. Magnetic susceptibility measurements reveal that dried corkite undergoes a transition to a long-range, antiferromagnetically-ordered state below TN = 48 K, lower than that observed in the majority of jarosite phases, and indicative of further spin frustration. Curie-Weiss fitting of the measured magnetic susceptibility yields an effective magnetic moment of peff = 6.29(1) muB/Fe^3+ and theta_CW = -526.0(1.1) K, analogous to that observed in similar high-spin Fe^3+ systems, and indicative of strong antiferromagnetic coupling. Estimation of the change in magnetic entropy as a function of temperature from T = 0 K to T = 195 K, dS_mag = 14.86 J/mol_Fe^3+ K, is also in good agreement with the dS_mag = Rln(2S+1) = 14.9 J/mol K expected for a S = 5/2 system. In comparison to the pure jarosites, where both structure and magnetism remain largely invariant upon a variety of chemical substitutions, the replacement of one sulfate group per formula unit with a higher-valent phosphate group applies additional steric and electronic pressure on the kagom\'e lattice in corkite, further frustrating the magnetic ground state of the material. Corkite thus represents both an outlier in the known body of jarosite-type materials, and an illustration of how existing structures may be further strained in the development of highly frustrated magnetic systems.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript reports the hydrothermal synthesis of corkite PbFe3(PO4)(SO4)(OH)6 and its first magnetic characterization as an S=5/2 kagomé antiferromagnet. Synthetic samples are claimed to exhibit a more ordered polyanion arrangement (retaining inversion symmetry) based on IR/Raman spectral signatures relative to natural samples. This ordering, combined with phosphate-for-sulfate substitution, is asserted to apply additional steric/electronic pressure on the kagomé lattice, resulting in long-range antiferromagnetic order below TN=48 K (lower than most jarosites and indicative of enhanced frustration). Supporting data include magnetic susceptibility with Curie-Weiss parameters peff=6.29(1) μB/Fe³⁺ and θCW=-526.0(1.1) K, plus magnetic entropy release of 14.86 J mol⁻¹ K⁻¹ consistent with R ln(6) for S=5/2.

Significance. If the polyanion ordering is real and causally linked to the reduced TN, the work adds a chemically tunable member to the jarosite family, illustrating how polyanion substitution can increase frustration beyond the largely invariant behavior seen in pure jarosites. The conventional analysis methods and close agreement of the entropy with the expected S=5/2 value strengthen the magnetic characterization.

major comments (2)
  1. [IR/Raman spectroscopy results and discussion of structural ordering] The central interpretation that the ordered polyanion arrangement (retaining inversion symmetry) is responsible for the reduced TN=48 K and increased frustration is supported only by differences in IR and Raman spectra versus natural samples. No Rietveld refinement, space-group assignment from diffraction, or bond-length metrics are described to confirm the ordering or quantify steric/electronic pressure on the kagomé lattice, leaving defects, partial occupancy, or impurities as viable alternative explanations for the magnetic behavior.
  2. [Magnetic properties and comparison to jarosites] The claim that TN=48 K is lower than the majority of jarosite phases (and thus indicative of further frustration) would be strengthened by explicit numerical comparison to specific jarosite TN values in a table or cited references, rather than a qualitative statement.
minor comments (2)
  1. [Magnetic susceptibility measurements] The temperature range and any constraints used for the Curie-Weiss fit (yielding θCW and peff) are not specified; adding these details would aid reproducibility.
  2. [Experimental methods] Clarify whether all reported measurements (including susceptibility) were performed on dried samples, as the abstract refers to 'dried corkite' while the synthesis description does not.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive comments and recommendation of minor revision. We address each major comment below.

read point-by-point responses

  1. Referee: [IR/Raman spectroscopy results and discussion of structural ordering] The central interpretation that the ordered polyanion arrangement (retaining inversion symmetry) is responsible for the reduced TN=48 K and increased frustration is supported only by differences in IR and Raman spectra versus natural samples. No Rietveld refinement, space-group assignment from diffraction, or bond-length metrics are described to confirm the ordering or quantify steric/electronic pressure on the kagomé lattice, leaving defects, partial occupancy, or impurities as viable alternative explanations for the magnetic behavior.

    Authors: We acknowledge that the evidence for polyanion ordering in synthetic corkite rests on the IR and Raman spectral signatures relative to natural samples, which show features consistent with a more symmetric arrangement that retains inversion symmetry. The manuscript does not include Rietveld refinements, explicit space-group assignments from diffraction, or quantitative bond-length analysis, as the primary emphasis is on the hydrothermal synthesis route and the magnetic properties. Alternative explanations such as defects or impurities cannot be fully excluded on the basis of the data presented. In the revised manuscript we will add a clarifying paragraph in the discussion section noting the indirect nature of the spectroscopic evidence for ordering and stating that additional diffraction-based structural work would be required to quantify any steric or electronic pressure on the kagomé lattice. revision: partial

  2. Referee: [Magnetic properties and comparison to jarosites] The claim that TN=48 K is lower than the majority of jarosite phases (and thus indicative of further frustration) would be strengthened by explicit numerical comparison to specific jarosite TN values in a table or cited references, rather than a qualitative statement.

    Authors: We agree that a quantitative comparison would strengthen the manuscript. In the revised version we will insert a short table (or an expanded paragraph with citations) listing representative TN values for jarosite-family compounds drawn from the literature, thereby demonstrating that 48 K lies below the majority of reported ordering temperatures. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental synthesis, spectra, and susceptibility data with standard fits; no derivations or self-referential predictions.

full rationale

The paper reports hydrothermal synthesis, IR/Raman characterization, magnetic susceptibility, Curie-Weiss fits, and entropy integration. All quantities are direct measurements or standard analysis (e.g., comparison of integrated dS_mag to the known R ln(2S+1) value for S=5/2). No equations, fitted parameters relabeled as predictions, self-citation chains, or ansatzes appear in the load-bearing claims. The attribution of lower TN to polyanion ordering is an interpretation of spectral differences versus natural samples, not a reduction by construction to the input data.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

The central claims rest on standard assumptions about sample purity, the validity of Curie-Weiss fitting for this temperature range, and the assignment of spectral features to polyanion ordering. No ad-hoc parameters or invented entities are introduced beyond conventional fitting of susceptibility data.

free parameters (2)
  • Curie-Weiss temperature θCW
    Fitted parameter from susceptibility data; value -526.0(1.1) K reported but is a direct fit, not an input to the claim.
  • effective moment peff
    Fitted parameter 6.29(1) μB/Fe3+ from the same data.
axioms (2)
  • domain assumption Fe3+ ions are in high-spin S=5/2 state
    Invoked when comparing measured peff and entropy to expected R ln(2S+1) value.
  • domain assumption Standard Curie-Weiss law applies above TN
    Used to extract θCW and peff from susceptibility.

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Reference graph

Works this paper leans on

30 extracted references · 30 canonical work pages

  1. [1]

    Recent Progress on 2D Kagome Magnets: Binary T_mSn_n (T= Fe, Co, Mn)

    Zhang, H.; Feng, H.; Xu, X.; Hao, W.; Du, Y. Recent Progress on 2D Kagome Magnets: Binary T_mSn_n (T= Fe, Co, Mn). Adv. Quantum Technol. 2021, 4, 2100073

    work page 2021

  2. [2]

    M.; Yin, J.-X.; Thomale, R.; Hasan, M

    Neupert, T.; Denner, M. M.; Yin, J.-X.; Thomale, R.; Hasan, M. Z. Charge order and superconductivity in kagome materials. Nat. Phys. 2022, 18, 137--143

    work page 2022

  3. [3]

    P.; Nytko, E

    Shores, M. P.; Nytko, E. A.; Bartlett, B. M.; Nocera, D. G. A structurally perfect S= 1/2 kagome antiferromagnet. J. Am. Chem. Soc. 2005, 127, 13462--13463

    work page 2005

  4. [4]

    Spin-1/2 Kagom \'e -Like Lattice in Volborthite Cu3V2O7(OH)2 2 H2O

    Hiroi, Z.; Hanawa, M.; Kobayashi, N.; Nohara, M.; Takagi, H.; Kato, Y.; Takigawa, M. Spin-1/2 Kagom \'e -Like Lattice in Volborthite Cu3V2O7(OH)2 2 H2O . J. Phys. Soc. Japan 2001, 70, 3377--3384

    work page 2001

  5. [5]

    Meschke, V.; Gorai, P.; Stevanovi \' c , V.; Toberer, E. S. Search and Structural Featurization of Magnetically Frustrated Kagom \' e Lattices . Chem. Mater. 2021, 33, 4373--4381

    work page 2021

  6. [6]

    G.; Papoutsakis, D

    Grohol, D.; Nocera, D. G.; Papoutsakis, D. Magnetism of pure iron jarosites . Phys. Rev. B 2003, 67, 064401

    work page 2003

  7. [7]

    C.; Peterson, R

    Basciano, L. C.; Peterson, R. C. Jarosite–hydronium jarosite solid-solution series with full iron site occupancy: Mineralogy and crystal chemistry . Am. Min. 2007, 92, 1464--1473

    work page 2007

  8. [8]

    Magnetic structure of the kagom \' e lattice antiferromagnet potassium jarosite

    Inami, T.; Nishiyama, M.; Maegawa, S.; Oka, Y. Magnetic structure of the kagom \' e lattice antiferromagnet potassium jarosite . Phys. Rev. B 2000, 61, 12181

    work page 2000

  9. [9]

    S.; Harrison, A.; Ritter, C.; Smith, R

    Wills, A. S.; Harrison, A.; Ritter, C.; Smith, R. I. Magnetic properties of pure and diamagnetically doped jarosites: Model kagom \' e antiferromagnets with variable coverage of the magnetic lattice . Phys. Rev. B 2000, 61, 6156

    work page 2000

  10. [10]

    Yildirim, T.; Harris, A. B. Magnetic structure and spin waves in the Kagom \'e jarosite compound KFe3(SO4)2(O H)6 . Phys. Rev. B 2006, 73, 214446

    work page 2006

  11. [11]

    Grohol, D.; Nocera, D. G. Magnetic Disorder in the Frustrated Antiferromagnet Jarosite Arising from the H3O+ OH- Interaction . Chem. Mater. 2007, 19, 3061--3066

    work page 2007

  12. [12]

    M.; Nocera, D

    Bartlett, B. M.; Nocera, D. G. Long-Range Magnetic Ordering in Iron Jarosites Prepared by Redox-Based Hydrothermal Methods . J. Am. Chem. Soc. 2005, 127, 8985--8993

    work page 2005

  13. [13]

    Interlayer exchange in the plumbo-jarosites: kagom \'e systems

    Wills, A.; Smith, A.; Dubbin, W.; Hudson-Edwards, K.; Wright, K. Interlayer exchange in the plumbo-jarosites: kagom \'e systems. J. Magn. Magn. Mater. 2004, 272, 1300--1301

    work page 2004

  14. [14]

    Corkite, PbFe3(PO4)(SO4)(OH)6 , its crystal structure and ordered arrangement of the tetrahedral cations

    Giuseppetti, G.; Tadini, C. Corkite, PbFe3(PO4)(SO4)(OH)6 , its crystal structure and ordered arrangement of the tetrahedral cations. Neues Jahrb. für Mineral. Monatshefte 1987, 2, 71--81

    work page 1987

  15. [15]

    L.; Palmer, S

    Frost, R. L.; Palmer, S. J. A vibrational spectroscopic study of the mineral corkite PbFe_3^ 3+ (PO4,SO4)2(OH)6 . J. Mol. Struct. 2011, 988, 47--51

    work page 2011

  16. [16]

    M.; Nocera, D

    Bartlett, B. M.; Nocera, D. G. Long-range magnetic ordering in iron jarosites prepared by redox-based hydrothermal methods. J. Am. Chem. Soc. 2005, 127, 8985--8993

    work page 2005

  17. [17]

    VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data

    Momma, K.; Izumi, F. VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. J. Appl. Crystallogr. 2011, 44, 1272--1276

    work page 2011

  18. [18]

    R.; Slade, P

    Kolitsch, U.; Tiekink, E. R.; Slade, P. G.; Taylor, M. R.; Pring, A. Hinsdalite and plumbogummite, their atomic arrangements and disordered lead sites. Eur. J. Mineral. 1999, 11, 513--520

    work page 1999

  19. [19]

    The crystal structure of kintoreite, PbFe3(PO4)2 (OH,H2O)6

    Taylor, M.; Bevan, D.; Pring, A. The crystal structure of kintoreite, PbFe3(PO4)2 (OH,H2O)6 . Mineral. Mag. 1997, 61, 123--129

    work page 1997

  20. [20]

    Szymanski, J. T. The crystal structure of beudantite, Pb(Fe,Al)3[(As,S)O4]2(OH)6 . Can. Mineral. 1988, 26, 923--932

    work page 1988

  21. [21]

    Baker, W. E. Mineral Chemistry and Mineralogy of the Lead Bearing Members of the Beudantite and Related Mineral Groups; University of NSW, 1962

    work page 1962

  22. [22]

    Grohol, D.; Nocera, D. G. Hydrothermal oxidation- reduction methods for the preparation of pure and single crystalline alunites: Synthesis and characterization of a new series of vanadium jarosites. J. Am. Chem. Soc. 2002, 124, 2640--2646

    work page 2002

  23. [23]

    L.; Murad, E

    Bishop, J. L.; Murad, E. The visible and infrared spectral properties of jarosite and alunite. Am. Mineral. 2005, 90, 1100--1107

    work page 2005

  24. [24]

    T.; Yang, H.; Stone, N

    Lafuente, B.; Downs, R. T.; Yang, H.; Stone, N. Highlights in mineralogical crystallography; De Gruyter, 2015; pp 1--30

    work page 2015

  25. [25]

    Shuker, R.; Gammon, R. W. Raman-Scattering Selection-Rule Breaking and the Density of States in Amorphous Materials. Phys. Rev. Lett. 1970, 25, 222--225

    work page 1970

  26. [26]

    Correlation of OH stretching frequencies and OH… O hydrogen bond lengths in minerals

    Libowitzky, E. Correlation of OH stretching frequencies and OH… O hydrogen bond lengths in minerals. Monatsh. Chem. 1999, 130, 1047--1059

    work page 1999

  27. [27]

    Luminescence in amorphous semiconductors

    Street, R. Luminescence in amorphous semiconductors. Adv. Phys. 1976, 25, 397--453

    work page 1976

  28. [28]

    The rule of mutual exclusion

    Venkatarayudu, T. The rule of mutual exclusion. J. Chem. Phys 1954, 22, 1269--1269

    work page 1954

  29. [29]

    Strongly geometrically frustrated magnets

    Ramirez, A. Strongly geometrically frustrated magnets. Annu. Rev. Mater. Sci. 1994, 24, 453--480

    work page 1994

  30. [30]

    Papoutsakis, D.; Grohol, D.; Nocera, D. G. Magnetic properties of a homologous series of vanadium jarosite compounds . J. Am. Chem. Soc. 2002, 124, 2647--2656 mcitethebibliography main.tex0000664000000000000000000013705114274215301011232 0ustar rootroot [journal=inoraj,manuscript=article] achemso acs articletitle = true [version=3] mhchem chemformula amsm...

    work page 2002