# PVDF fluorination of La4Co3O10: Synthesis, structure and physical properties of La4Co3O10F2

Bruno Gonano, Øystein Slagtern Fjellvåg, Gwladys Steciuk, Kenneth Marshall, Helmer Fjellvåg, Martin Valldor

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Bruno Gonano, Øystein Slagtern Fjellvåg, Gwladys Steciuk, Kenneth Marshall, Helmer Fjellvåg, et al.. PVDF fluorination of La4Co3O10: Synthesis, structure and physical properties of La4Co3O10F2. Scripta Materialia, 2025, 255, pp.116379. 10.1016/j.scriptamat.2024.116379. hal-05122131

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# PVDF fluorination of La₄Co₃O₁₀: Synthesis, structure and physical properties of La₄Co₃O₁₀F₂

Bruno Gonano<sup>a, *,</sup>, Øystein Slagtern Fjellvåg<sup>b</sup>, Gwladys Steciuk<sup>c</sup>, Kenneth Marshall<sup>d</sup>, Helmer Fjellvåg<sup>a</sup>, Martin Valldor<sup>a</sup>

## ARTICLE INFO

**Keywords:**
Oxyfluorides
Mixed-anions
Crystal structure

## ABSTRACT

Topochemical fluorination of oxides recently gained interest as it opens the way to substantial structural modifications and drastic changes in physical properties. We present a study of La₄Co₃O₁₀F₂, synthesized via low-temperature topochemical methods using polyvinylidene difluoride (PVDF). Using synchrotron X-ray powder diffraction, we find the compound to crystallize in a monoclinic cell (A2/a, with $a = 5.32969(9)$ Å, $b = 5.37555(1)$ Å, $c = 30.5958(6)$ Å and $\beta = 90.994(1)$ °), where the fluoride anions occupy the rock-salt layer's interstitial sites, inducing a tilting of the CoO₆ octahedra. The physical properties of this novel compound are compared with those of the parent compound La₄Co₃O₁₀, evidencing changes in resistivity and magnetism, highlighting the possibility of tuning magnetic interactions and electronic correlations through PVDF fluorination.

Ruddlesden-Popper (RP) phases [1,2] (with general formula $A_{n+1}B_nO_{3n+1}$) can be described as a regular intergrowth between $n$ perovskite layers (ABO₃) separated by NaCl-like layers (AO). They have attracted considerable attention over the past few decades due to their diverse physical properties and potential applications in various fields, including superconductivity [3–6], and magnetoresistance [7,8]. While for a long time, research mainly focused on oxide materials where cations were substituted to tailor the physical properties, anionic manipulations of the oxygen lattice using $H^-$ (oxyhydrides [9,10]), $N^{3-}$ (oxynitrides [11–13]) or $F^-$ (oxyfluorides [14–16]) remained largely underexplored considering their potential, partially due to the complex and sometimes dangerous synthesis routes required. However, such modifications, for example, in the Ruddlesden-Popper family, have been shown to affect the electronic state of the transition metal, opening the way to potentially new and exotic physical phenomena [17–20].

Ruddlesden-Popper (RP) oxyfluorides gained a boost of interest with the discovery of High-$T_c$ superconductivity in Cu-compounds, firstly with Sr₂CuO₂F₂+δ [21] ($T_c$ = 46 K), derived from the Sr$_{n+1}$Cu$_n$O$_{2n+1+δ}$ ($n = 1, 2, 3,...) family [22]. Sr₂CuO₂F₂+δ crystallizes in an orthorhombic cell (Fmmm) with $a = 5.394(1)$ Å, $b = 5.513(1)$ Å and $c = 13.468(3)$ Å, closely related to the La₂CuO₄+δ structure, where $F^-$ ions occupy the

apical sites and interstitial sites between the SrF layers, forming insulating blocks. Routes to produce this oxyfluoride are complex and involve optimized gas-flow protocols [23]. This underlines the need for easier access to the two-anion chemistry—a low-temperature synthesis method would be ideal.

Recently, Polyvinylidene Difluoride (PVDF) topochemical fluorination emerged as a new strategy to produce RP oxyfluorides, as it allows for low-temperature synthesis of compounds that are excessively difficult to obtain through conventional methods. Wissel et al. reported La₂NiO₃F₂ [24] and reduced analogues, the first RP oxyfluoride compound in the Ni-system, obtained from a mixture of La₂NiO₄ and PVDF, treated at 370 °C. The structure exhibits strong tilting of NiO₄F₂ octahedra combined with an apical $F^-$ ordering, leading to an orthorhombic distortion. Such structural modifications open the way to exciting applications, also as cathode materials, as demonstrated by La₂CoO₄F₁.₂ [25]. This material exhibits a discharge capacity of 32 mAh g⁻¹, making it a suitable candidate for intercalation-based fluoride-ion battery cathodes.

These examples highlight the extraordinary playground opened by topochemical fluorination, where well-known oxide compounds can be used as precursors. Here, we report the novel, F-intercalated RP phase

<footnote><sup>a</sup> Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, PO Box 1033 Blindern, N-0315 Oslo, Norway</footnote>

<footnote><sup>b</sup> Department for Neutron Materials Characterization, Institute for Energy Technology, PO Box 40, NO-2027, Kjeller, Norway</footnote>

<footnote><sup>c</sup> Institute of Physics of the CAS, v.v.i., Na Slovance 1999/2, 18221 Prague 8, Czech Republic</footnote>

<footnote><sup>d</sup> Swiss-Norwegian Beam Lines at European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38043 Grenoble, France</footnote>

<footnote>* Corresponding author.
E-mail address: b.r.g.gonano@smn.uio.no (B. Gonano).</footnote>
La₄Co₃O₁₀F₂, which was synthesized via a low-temperature top-
ochemical fluorination process of La₄Co₃O₁₀. La₄Co₃O₁₀+δ has been
extensively studied in our group over the last decades [26,27]. The
compound has shown a strong flexibility in oxygen stoichiometry,
creating the possibility to tune the oxidation state of the cobalt cation
and therefore modify the electronic and magnetic properties. The pos-
sibility of inserting O²⁻ in the rock-salt layer makes it a promising
candidate for the introduction of another anion in the same position. In
this work, we look at the impact of F⁻ intercalation on the crystal
structure and the physical properties compared to those of the parent
La₄Co₃O₁₀.₀₀ (from now La₄Co₃O₁₀).

The reaction between La₄Co₃O₁₀ and PVDF was investigated by SPXRD as a function of temperature. Powders were mixed with a 1:1 molar ratio, and filled in quartz capillaries, which were heated while diffraction patterns were collected. At the beginning of the heating sequence, a normal thermal expansion is observed (Fig. 1). At about 350 °C, a reaction starts, as indicated by the appearance of new diffraction peaks. The development of the diffraction peaks is discontinuous, and we assume the reaction to be first order. At 370 °C, the reaction is completed, and no further change is observed when holding the sample at 370 °C. Further heating shows the new phase to be stable up to at least 550 °C.

The preparation of the new phase was reproduced by mixing and heating of polycrystalline powders in a conventional furnace at 370 °C and the diffraction pattern of the final product was identical to that from the heating experiment. The crystal structure description of the new phase was attempted based on SPXRD data collected at room temperature. All peaks were indexed and described in a Le Bail fit in a monoclinic cell [A2/a, with *a* = 5.32969(9) Å, *b* = 5.3755(1) Å, *c* = 30.5958 (6) Å and *β* = 90.994(1) °]. No additional peaks from secondary phases were detected.

First, we observe that the basal plane (a, b) is comparable to that of
the pure oxide compound La₄Co₃O₁₀ [C2/m, with *a* = 5.4179(1) Å, *b* =
5.4756(1) Å, *c* = 27.805(1) Å and *β* = 90.200(1) °]. Second, a large
stacking parameter, *c* (>30 Å), was detected, almost 3 Å longer than that
of the pure oxide compound La₄Co₃O₁₀. The elongation along *c* suggests
an insertion of F⁻ in the rock-salt layer at interstitial sites, which is a
known phenomenon from other RP oxyfluorides e.g. La₂SrCr₂O₇F₂ [15].
The crystal structure determination of La₄Co₃O₁₀F₂ started by assuming
the cationic network was closely related to that of the pure oxide, and
the reported crystal structure of La₄Co₃O₁₀ was used as an initial model
for the first steps of the refinement. Cation positions and displacement
parameters could be freely refined and confirm the similarity with the
parent compound. The difference between Fourier transforms (calcu-
lated-experimental) revealed residual electronic densities in the

interstitial positions of the rock-salt layers. Fluoride anions were inser-
ted into the structural model, drastically improving the agreement be-
tween observed and calculated models.

The fluoride anion content was evaluated by refining occupancies of F1 and F2, both converging to unity. Subsequently, oxygen positions and occupancies were refined and confirmed the full occupancy of the sites and the proposed nominal composition. All oxygen sites are well described by isotropic thermal displacement parameters. The refinement gave excellent reliability factors with R<sub>p</sub> = 0.0157, wR<sub>p</sub> = 0.0244, R<sub>obs</sub> = 0.0234, wR<sub>obs</sub> = 0.0326 and GOF = 0.21 (refined parameters = 65). In the final Rietveld refinement (Fig. 2), zero error, lattice parameters, atomic positions, and isotropic displacement factors were refined. Tables 1 and 2 present the crystallographic parameters obtained from the final Rietveld refinement. La<sub>4</sub>Co<sub>3</sub>O<sub>10</sub>F<sub>2</sub> structure was deposited in the CCDC database under the deposition number 2360498. Fig. 3 shows the atomic structures of both La<sub>4</sub>Co<sub>3</sub>O<sub>10</sub> and La<sub>4</sub>Co<sub>3</sub>O<sub>10</sub>F<sub>2</sub>. The crystal structure of La<sub>4</sub>Co<sub>3</sub>O<sub>10</sub>F<sub>2</sub> can be described as an RP phase with *n* = 3 with fluorine inserted into the rock salt layer. Thus, the compound is constructed from perovskite slabs that are three octahedra long and are separated by half a rocksalt layer. The fluorine atoms adopt tetrahedral sites in the rock salt layer, with La-F bonds in the range from 2.51(2) Å to 2.64(2) Å, indicating a slight distortion of the tetrahedra. The cobalt-oxygen polyhedra are more distorted for the oxyfluoride than for the corresponding oxide. The oxidation of cobalt is also evident from the reduction of the polyhedral volume from the oxide to the oxyfluoride, and the Bond Valence Sum calculations presented in Table S1 show an oxidation from 2.545 to 2.838. The Co-O bond distances are within the expected range, Table 2.

DC magnetization versus temperature data were measured on poly-
crystalline La₄Co₃O₁₀ and La₄Co₃O₁₀F₂ samples between 5 and 300 K
under 1000 Oe and 10,000 Oe fields (Fig. 4). The fluorinated oxide,
La₄Co₃O₁₀F₂, exhibits no obvious, magnetic phase transition in the
measured temperature range, and ZFC and FC data superimpose well at
higher temperatures.

In contrast, ZFC and FC data, measured in a 1000 Oe magnetic field, are significantly different below about 75 K, which can be explained by a spin-domain effect. AC measurements (Supporting Information 1) do not show any frequency dependence in that range, infirming typical spin-glass or superparamagnetic spin-freezing scenarios. The relatively strong antiferromagnetic spin-to-spin interactions, as suggested by the Weiss-constant ($\theta$ = -202 K, Fig. 4), could lead to short-range order within the Co layers. Note that the introduction of F⁻, increasing the distance between the perovskite slabs, obviously results in a more 2D-like magnetic behaviour. By comparing this magnetic behaviour with that of the oxide, La₄Co₃O₁₀, it is apparent that the intra-layer magnetic

<figure><img src="image_2.png" /><figcaption>**Fig. 1.** SPXRD data as a function of temperature, showing the formation of a new phase when reacting La₄Co₃O₁₀ and PVDF. The reaction starts at about 350 °C.</figcaption></figure>
<figure><img src="image_3.png" /><figcaption>**Fig. 2.** Experimental (black circles), calculated (red line) and difference (blue line) SPXRD patterns of La₄Co₃O₁₀ (a) and La₄Co₃O₁₀F₂ (b) according to Rietveld refinement. Bragg peak positions are indicated with green ticks.</figcaption></figure>

**Table 1**

Positional parameters extracted from Rietveld refinement of La₄Co₃O₁₀F₂ in space group A2/a with a = 5.32969(9) Å, b = 5.3755(1), c = 30.5958(6) Å and β = 90.994(1)°.

<table><thead><tr><th>Atom</th><th>x</th><th>y</th><th>z</th><th>Uiso</th><th>Occ.</th><th>Wyck. Site</th></tr></thead><tbody><tr><td>La1</td><td>-0.0069<br>(4)</td><td>0.2447<br>(12)</td><td>0.44390(5)</td><td>0.0048<br>(4)</td><td>1</td><td>8f</td></tr><tr><td>La2</td><td>-0.0015<br>(4)</td><td>0.2482<br>(12)</td><td>0.31282(6)</td><td>0.0045<br>(3)</td><td>1</td><td>8f</td></tr><tr><td>Co1</td><td>-0.4992<br>(8)</td><td>0.248(3)</td><td>0.37699<br>(10)</td><td>0.0014<br>(7)</td><td>1</td><td>8f</td></tr><tr><td>Co2</td><td>0.5</td><td>0.25</td><td>0.25</td><td>0.003<br>(1)</td><td>1</td><td>4c</td></tr><tr><td>F1</td><td>0.25</td><td>0.476(7)</td><td>0.5</td><td>0.01(1)</td><td>1</td><td>4e</td></tr><tr><td>F2</td><td>0.25</td><td>-0.022<br>(8)</td><td>0.5</td><td>0.04(2)</td><td>1</td><td>4e</td></tr><tr><td>O1</td><td>-0.284(5)</td><td>0.556(4)</td><td>0.3788(7)</td><td>0.001(5)</td><td>1</td><td>8f</td></tr><tr><td>O2</td><td>0.273(5)</td><td>0.459(4)</td><td>0.8702(7)</td><td>0.001(5)</td><td>1</td><td>8f</td></tr><tr><td>O3</td><td>0.465(3)</td><td>0.204(4)</td><td>0.3120(5)</td><td>0.001(4)</td><td>1</td><td>8f</td></tr><tr><td>O4</td><td>0.287(5)</td><td>0.540(5)</td><td>0.2462(9)</td><td>0.001(5)</td><td>1</td><td>8f</td></tr><tr><td>O5</td><td>0.501(3)</td><td>0.272(8)</td><td>0.4360(4)</td><td>0.001(5)</td><td>1</td><td>8f</td></tr></tbody></table>

coupling still leads to an anomaly close to 75 K (Fig. 4), but there is, in contrast, a second anomaly close to 10 K for the oxide, which could be due to a more long-ranged antiferromagnetic ordering; the interlayer magnetic interactions are stronger in the oxide than in the fluorinated compound.

**Table 2**

Selected bond distances and angles extracted from Rietveld refinement of La₄Co₃O₁₀F₂.

<table><thead><tr><th>Bond</th><th>Distance (Å)</th><th>Bond</th><th>Distance (Å)</th></tr></thead><tbody><tr><td>La1—F1</td><td>2.51(2)—2.64(2)</td><td>Co1—O3</td><td>2.01(2)</td></tr><tr><td>La1—F2</td><td>2.48(2)—2.61(2)</td><td>Co1—O5</td><td>1.81(1)</td></tr><tr><td>Co1—O1</td><td>1.85(2)—2.01(2)</td><td>Co2—O3</td><td>1.92(2)</td></tr><tr><td>Co1—O2</td><td>1.84(3)—1.98(2)</td><td>Co2—O4</td><td>1.91(3)—1.93(3)</td></tr></tbody></table><table><thead><tr><th>Bond</th><th>Angle (°)</th><th>Bond</th><th>Angle (°)</th></tr></thead><tbody><tr><td>Co2—O4—Co2</td><td>161.0(16)</td><td>O1—Co1—O2</td><td>92.8(10)</td></tr><tr><td>Co1—O3—Co2</td><td>162.1(11)</td><td>La1—F1—La1</td><td>96.04(15)</td></tr><tr><td>Co1—O2—Co1</td><td>160.7(14)</td><td>La1—F2—La1</td><td>94.85(15)</td></tr></tbody></table>

Isothermal magnetizations at 300 K are in agreement with paramagnetic behaviour of the oxide and the fluorinated compound (Fig. 4). However, for the oxide at 5 K, a minor change of slope is observed at about 0.6 T, which could be a spin-reorientation with the antiferromagnetic state. As this anomaly is lacking in the fluorinated sample, it is yet another support for the lack of long-range spin-ordering in La₄Co₃O₁₀F₂. Naturally, a secondary phase, such as LaCoO₃ or La₂CoO₄ could also produce a similar effect, but no additional peaks were detected in the SPXRD, making it plausible that the magnetization anomaly in the oxide at 5 K is of intrinsic nature.

The inverse of magnetic susceptibility is presented in the inset of Fig. 4. The associated Curie-Weiss fit gives a value for the Weiss temperature of θ = -202 K for La₄Co₃O₁₀F₂, in agreement with antiferromagnetic behaviour. The effective magnetic moment is 3.59 μB per formula unit. Note here that these values are extracted from a fit performed in the paramagnetic region, despite the slight curvature, possibly attributed to a low-spin/high-spin transition. The Curie-Weiss fit for the oxide gives a slightly positive Weiss temperature (θ = 7.7 K), and an effective magnetic moment of 4.48 μB per formula unit, in agreement with previous reports [27].

The electric resistivity of La₄Co₃O₁₀ and La₄Co₃O₁₀F₂ were measured on sintered, polycrystals (Fig. 5a), making a direct qualitative comparison possible, but quantitative analysis less reliable. The conductivity of the oxyfluoride is about two orders of magnitude larger, which is remarkable considering that F⁻ is associated with strong electronic correlations. Instead, the exact electron distribution must be decisive for improving the conductivity in the fluorinated compound. A typical Mott variable-range hopping mechanism in low dimensions is well describing the temperature dependence of resistivity of La₄Co₃O₁₀F₂ (Fig. 5b).

According to heat capacity measurements (Fig. 5c and d), both Cₚ(T) curves saturate relatively close to the theoretical Dulong-Petit limit (3nR, with n as the number of individual atoms in the formula unit and R as the gas constant (8.3145 J mol⁻¹ K⁻¹)). However, for both compounds, there seems to be entropy release at lower temperatures, indicating phase transitions. In La₄Co₃O₁₀F₂, the anomaly is relatively smaller, close to the resolution limit, and centered around 4 K. However, in La₄Co₃O₁₀, the anomaly is prominent and of second-order type with a characteristic asymmetry towards lower temperatures. This entropy release has its maximum close to 9 K, which agrees with the magnetic anomaly. By simple integration, subtracting a simple phononic background, the released entropy corresponds to 1.77 J mol⁻¹ K⁻¹, significantly lower than the theoretical magnetic entropy from a system with 2R*ln(2S + 1), assuming CoII(HS)/CoIII(LS) (11.5 J mol⁻¹ K⁻¹), as suggested in the literature [22]. This confirms the long-ranged spin-ordering in La₄Co₃O₁₀, and the lack of obvious spin-order in La₄Co₃O₁₀F₂. In the latter, the minor entropy release at low temperatures is most likely connected to the change in oxidation state and bond distances and further investigations at low temperatures have to be performed.

Sr₂CoO₃F [28] is, to the best of our knowledge, the first cobalt RP oxyfluoride, and is prepared at 6 GPa at 1700 °C. Similarly, the nickel oxyfluoride Sr₂NiO₃F [29] synthesis requires 6 GPa at 1500 °C, which
<figure><img src="image_4.png" /><figcaption>Fig. 3. Left: Crystal structure and polyhedral connectivity of La₄Co₃O₁₀. Right: Crystal structure, polyhedral connectivity and site labels of La₄Co₃O₁₀F₂.</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>Fig. 4. Zero-field cooled and field cooled magnetic susceptibility measurements of La₄Co₃O₁₀ (a) and La₄Co₃O₁₀F₂ (b) under a field of 1000 Oe (blue) and 10,000 Oe (red). Inset: Inverse magnetic susceptibility and Curie-Weiss fit. M(H) curves of La₄Co₃O₁₀ (c) and La₄Co₃O₁₀F₂ (d) at 5 (dark green) and 300 K (light green) between –5 and 5T.</figcaption></figure>

puts the mild synthesis conditions of 370 °C used for La₄Co₃O₁₀F₂ into perspective. In addition, topochemical fluorination via PVDF represents a relatively non-toxic and safe synthesis route, in contrast to the synthesis of La₂SrCr₂O₇F₂, where CuF₂ is used as a fluorine donor and can

either be a source of impurity (with the formation of CuO) or increase the F₂-gas related risks [15].

In contrast to the direct synthesis for Sr₂CoO₃F where the oxyfluoride is directly formed, topochemical fluorination is a designated method to
<figure><img src="image_6.png" /><figcaption>**Fig. 5.** (a) Resistivity versus temperature measurements of La₄Co₃O₁₀ (grey) and La₄Co₃O₁₀F₂ (blue). (b) Resistivity of La₄Co₃O₁₀F₂ versus (1/T)⁻¹/₄ corresponding to a Mott variable-range hopping mechanism. Specific heat capacity measurements for La₄Co₃O₁₀ (c) and La₄Co₃O₁₀F₂ (d) and the calculated Dulong-Petit limit (red).</figcaption></figure>

insert a second anion into a compound, which typically results in different structural features of the oxyfluorides obtained. Indeed, by topochemical fluorination, the fluoride anions are inserted at interstitial sites, e.g. in the rock salt layer of an RP phase, while by direct synthesis the fluoride anions are typically becoming a part of the constructing units of the crystal structure, e.g. an apical or equatorial site of an octahedra. La₄Co₃O₁₀F₂ is an excellent example of a RP-related compound where fluoride is inserted topochemically as a second anion. It presents similarities with the *n* = 2 RP structure La₂SrCr₂O₇F₂, where the fluoride anions are also inserted in the rock salt layer. The addition of anions into the atomic arrangement, in these cases, is intriguing as it alters the electronic ground state.

Long-range magnetic order in isotropic 2D materials is prohibited according to the Mermin-Wagner theorem [30]. RP phases have layered structures, yet they are sufficiently 3D to order magnetically. Increased separation of magnetic layers by an additional La-F layer may lower the magnetic dimensionality, and thus hinder long-range magnetic order. For La₄Co₃O₁₀ and La₄Co₃O₁₀F₂ it is difficult to distinguish effects caused by a lowering of dimensionality from increased layer spacing and a change in the oxidation state of cobalt. The change in oxidation state of Co: in La₄Co₃O₁₀, cobalt has a mean oxidation state of +8/3 but could be treated as a disordered mixture of one Co²⁺ and two Co³⁺. The Curie-Weiss fit and the extracted effective magnetic moment (4.48 µB per formula unit) are in agreement with the theoretical effective magnetic moment (4.56 µB per formula unit, assuming Co<sup>II</sup>(HS)/Co<sup>III</sup>(LS) and the literature [22]. Interestingly, Co in La₄Co₃O₁₀F₂ would have an

average oxidation state of +10/3, leaving no other option than to assume a mixture of one Co⁴⁺ and two Co³⁺, unless a hole remains on an oxygen ion and cobalt is homogenously +3. The effective magnetic moment (3.59 µB per formula unit) is in agreement with a Co<sup>III</sup>(HS)/-Co<sup>IV</sup>(LS) (theoretical 3.87 µB per formula unit), where the theoretical effective magnetic moment for a hole/Co<sup>III</sup> (HS) configuration is 4.9 µB per formula unit. However, without additional data on the fluorinated compound, its exact electron configuration cannot be settled.

In this work, we have presented the oxyfluoride La₄Co₃O₁₀F₂ prepared by topochemical fluorination by reacting La₄Co₃O₁₀ and PVDF. La₄Co₃O₁₀F₂ is a RP *n* = 3 phase with fluoride inserted in the rock salt layer, and the crystal structure is described by Rietveld refinements of SPXRD data. The work demonstrates how topochemical fluorination can tune the crystal structure, magnetic interactions and electronic correlations. The spin-spin interactions in the paramagnetic regime go from strongly negative to slightly positive for the oxyfluoride. No signs of long-range magnetic ordering are observed for La₄Co₃O₁₀F₂, either with susceptibility or heat capacity measurements. The oxyfluoride has two orders of magnitude lower resistivity than the oxide, and a typical Mott variable-range hopping mechanism in low dimensions describes the temperature dependence well.

CRediT authorship contribution statement

**Bruno Gonano:** Writing – review & editing, Writing – original draft, Visualization, Validation, Methodology, Investigation, Formal analysis,
Conceptualization. Øystein Slagtern Fjellvåg: Writing – review & editing, Writing – original draft, Validation, Methodology, Investigation, Formal analysis, Conceptualization. Gwladys Steciuk: Writing – review & editing, Validation, Investigation, Formal analysis. Kenneth Marshall: Writing – review & editing, Methodology, Investigation. Helmer Fjellvåg: Writing – review & editing, Validation, Supervision, Methodology, Conceptualization. Martin Valldor: Writing – review & editing, Writing – original draft, Validation, Supervision, Resources, Methodology, Investigation, Funding acquisition, Formal analysis, Conceptualization.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgment

B.G. and Ø.S.F. acknowledge funding from the Research Council of Norway (NFR) through projects 325345, 301711, and 343193. The authors gratefully acknowledge the Norwegian Center for X-ray Diffraction, Scattering and Imaging (RECX) and the Swiss-Norwegian Beamlines (SNBL) at ESRF, NFR project 208896.

Supplementary materials

Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.scriptamat.2024.116379.

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