I11-High Resolution Powder Diffraction
|
Matthew
Wright
,
Stephen
Browne
,
Enrique
Moya
,
Amelia R.
Reach
,
Aina
Sebastian
,
Aliya
Abulajiang
,
Roland
Yin
,
Julissa
Cesareo
,
Jacey
Li
,
Alejandro
Tarin
,
Sarah H.
Tolbert
,
Brent C.
Melot
,
Anton
Van Der Ven
,
Ram
Seshadri
Diamond Proposal Number(s):
[36397, 41364]
Abstract: Layered Na–Mn–Fe–O oxides are among the leading cathode candidates for Na-ion batteries owing to their low cost, earth-abundant constituents, and competitive electrochemical performance. Their rich structural chemistry, spanning O-type (octahedral Na) and P-type (prismatic Na) polymorphs with distinct stacking sequences, offers multiple avenues for property optimization. However, controllable access to specific polymorphs, particularly nonequilibrium ones, remains a synthetic challenge. Here we show that susceptor-assisted microwave heating can produce the P2, O3, and P3 phases of layered Na–Mn–Fe–O cathodes in minutes, with phase selectivity set by the nominal Na/M ratio of the precursor alone. The rapid reaction times suppress Na volatilization, preserving the target stoichiometry without the excess sacrificial Na precursors typically required by conventional solid-state routes. The high mobility of Na+ combined with the large size difference between Na and Mn/Fe, yields well-ordered frameworks with no evidence for antisite disorder between Na+ and the transition metals. Accessing all three structures from one rapid route enables a controlled comparison of how stacking sequence governs electrochemistry. On cycling, we observe Fe3+/Fe4+ redox and behavior consistent with Fe3+ migration into the Na layer at high voltage in all three polymorphs, with P2 showing the most stable high-voltage cycling. Operando diffraction shows that all three converge toward disordered O-type stacking on deep desodiation, and voltage-resolved distribution-of-relaxation-times analysis shows that Na+ diffusion kinetics are governed by stacking transitions and Na–vacancy ordering, with pronounced kinetic barriers at glide-type structural transitions. These results establish microwave synthesis as a versatile route to both equilibrium and nonequilibrium layered Na cathodes and clarify how stacking sequence and local disorder jointly control redox behavior and ion transport.
|
Aug 2026
|
|
I22-Small angle scattering & Diffraction
|
Johanna
Heimonen
,
Cecilia
Bruschi
,
Asaminew Y.
Shimolo
,
Marle E. J.
Vleugels
,
Lukas
Marcos Celada
,
Sozan
Darabi
,
Viktor
Gueskine
,
Daniel
Primetzhofer
,
Christian
Müller
,
Bence
Fehér
,
Peter
Olsén
,
Renee
Kroon
Diamond Proposal Number(s):
[39422]
Open Access
Abstract: The transition to sustainable electronics requires electroactive materials that are processable in green solvents, operationally stable, and recyclable or recoverable at their end of life. This work explores recoverable electroactive cellulose coatings using a carboxylate-functionalized polar polythiophene (PCAT-K). PCAT-K is water-processable and can be reversibly fixated onto cellulose threads by modulation of the secondary interactions via acid–base chemistry, showing promise for circular material use. To obtain electrically conducting PCAT-K-cellulose threads, acid-mediated oxygen doping of the PCAT-K with p-toluenesulfonic acid was explored but led to undesired covalent cross-linking and loss of solubility and recoverability. Through spectroscopic and electrochemical analyses, it is shown that the covalent cross-linking originates from hydrogen peroxide generation during the doping process, which further reacts with PCAT to form hydroxyl radicals. To suppress radical formation, potassium iodide is introduced as a benign additive that catalytically decomposes hydrogen peroxide, preventing covalent cross-linking while maintaining electrical conductivity and recoverability. While the additive can negatively affect cellulose substrates at long doping times, this strategy allows for stable, conductive, and removable electroactive coatings on cellulose threads using water as the sole solvent. This study highlights a more reliable synthetic route to the water-processable conjugated polymer PCAT-K and suggests a mechanistic origin of acid-mediated oxygen doping-induced covalent cross-linking with a practical strategy to overcome it.
|
Jul 2026
|
|
B18-Core EXAFS
|
Diamond Proposal Number(s):
[41187]
Abstract: The sulfur redox mechanism in solid-state lithium–sulfur (Li–S) batteries remains unclear, as it has been reported to vary under different operating conditions due to sluggish reaction kinetics. Herein, we investigate sulfur reactions in solid-state batteries using solid electrolytes with high ionic conductivities to mitigate kinetic limitations. A solid-state Li–S cell employing Li5.5PS4.5Cl1.5 exhibits an asymmetric voltage profile at 25 °C, with two voltage plateaus during discharge and poorly separated oxidation reactions during charge. Ex situ X-ray absorption spectroscopy (XAS) elucidates that these poorly separated oxidation reactions consist of overlapping conversion reactions, in contrast to the clearly distinguishable two-step conversion from S8 to Li2S via Li2Sx during discharge. In addition, operando impedance evolution, analyzed using a combined distribution of relaxation times (DRT) and distribution of phasances (DOP) model, reveals distinct relaxation processes during discharge and charge that arise from differences in the transport properties of the reaction products. This work demonstrates an intrinsic asymmetric sulfur redox mechanism in solid-state batteries that is difficult to resolve by conventional electrochemical measurements alone but can be clarified by combining XAS with impedance analysis using the DRT-DOP model.
|
Jul 2026
|
|
I11-High Resolution Powder Diffraction
|
Diamond Proposal Number(s):
[36397]
Abstract: NaSICON (Na Super-Ionic CONductor) is a promising family of Na-ion solid electrolyte materials for Na-based all-solid-state and aqueous redox-flow batteries, with the most simple and well-studied compound being Na1+xZr2SixP3–xO12 (0 ≤ x ≤ 3), or NZSP. It has been recently shown through simulation and experiment that the bulk and total conductivities are maximized at x = 2.4. In the present study, NZSP of varying Na contents (2.0 ≤ x ≤ 2.8) has been synthesized through a solution-assisted solid-state reaction and densified using rapid-induction hot pressing (RIHP). The bulk and total conductivities, phase purity, and elemental composition were characterized with low-temperature impedance spectroscopy, synchrotron X-ray diffraction, and wavelength dispersive X-ray spectroscopy. For the first time, we report a maximum bulk conductivity at x > 2.4: an unprecedented average room temperature bulk conductivity of 3.6 × 10–2 S cm–1 is achieved at x = 2.6 and 2.8, and a remarkably high average total conductivity of 8.7 × 10–3 S cm–1 is achieved at x = 2.8. This trend deviates from the literature and was previously thought to be improbable due to the low vacancy concentration at high Na content. We showed that the bulk conductivity of an x = 2.8 sample decreased significantly after altering its thermal history, providing indirect evidence that cation disorder greatly affects Na transport, although further characterization is needed to fully understand the cause. The results of this study show how formulation, synthesis, and processing affect the conductivity and performance of NaSICON and help guide future research on NaSICON-based ceramic ion conductors.
|
Jul 2026
|
|
I11-High Resolution Powder Diffraction
|
Diamond Proposal Number(s):
[25166]
Abstract: Layered perovskite oxides continue to be the subject of intense research efforts due to their highly tunable crystal structures, which often arise from the competition between various lattice, spin, charge and orbital degrees of freedom. In particular, a number of recent works have focused on the mechanisms through which polar phases (those with globally broken inversion symmetry) emerge through the coupling of different structural distortions. The so-called hybrid improper mechanism, in which nonpolar structural distortions couple to break inversion symmetry, has been invoked to explain the appearance of polar structures in many different layered perovskite oxides. We use a combined experimental and computational approach to investigate the pseudo-Ruddlesden–Popper system Li2SrxCa1–xTa2O7 (0 < x < 1), which exhibits multiple competing polar phases that arise through distinct mechanisms. We untangle the complex interactions between various structural modes and find that, in contrast with previous work, the hybrid improper mechanism cannot by itself account for the observed polar phases. Our work demonstrates that there are significant differences in the mechanisms through which polar phases emerge in even nominally the same family of layered perovskites, suggesting a rich playground for further exploration and functional materials design.
|
Jun 2026
|
|
I11-High Resolution Powder Diffraction
|
Alexandra
Morscher
,
Lucia
Corti
,
Samuel L.
Goodwin
,
Andres
Acin-Lalanza
,
Matthew
Wright
,
T. Wesley
Surta
,
Ruiyong
Chen
,
Matthew S.
Dyer
,
Frédéric
Blanc
,
Luke M.
Daniels
,
John B.
Claridge
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[37989]
Open Access
Abstract: Sulfide lithium argyrodites are a key materials family that are studied as solid electrolytes in commercial all-solid-state batteries (ASSBs), while their oxide analogues remain relatively unexplored. This study presents the discovery of Li7TiO5X (X = Cl–, Br–), the first lithium argyrodite materials in which a transition metal is used as the framework-forming cation, expanding the chemical space that is accessible for oxide argyrodites. Incorporation of Ti4+ enables the lithium content to be maximized to 7 Li+ per formula unit. Interestingly, even with the high lithium content, Li7TiO5Cl retains a Li+ site disordered cubic F4̅3m structure at room temperature with Li+ occupancy of the T5, T5a, and T3 positions, and exhibits an ionic conductivity of 2.2(2) × 10–6 S cm–1 with the lowest reported activation energy (0.36(2) eV) for bulk Li+ ion transport in an oxide argyrodite. Conversely, Li7TiO5Br adopts the same F4̅3m symmetry at room temperature but with an ordered arrangement of Li+ positions via full occupancy of the T5a and T3 positions, and thus has an ionic conductivity that is 3 orders of magnitude lower (∼10–9 S cm–1) and a much higher activation energy (0.58(2) eV) than Li7TiO5Cl. Order–disorder behavior is observed below 250 K in Li7TiO5Cl, where a Li+ site ordering pattern is observed that is distinct from Li7TiO5Br and all sulfide argyrodites, yielding a tetragonal symmetry (I4̅) for only the second time to date in the argyrodite structure type. This unique order–disorder behavior, alongside the ability to incorporate transition metal cations within this material family emphasizes the potential to access much greater structural diversity via the expansive chemical space that is available for exploration in oxide argyrodites.
|
Jun 2026
|
|
I11-High Resolution Powder Diffraction
|
Diamond Proposal Number(s):
[38160]
Open Access
Abstract: Zn-substituted Na0.75Mn0.68Ni0.25Zn0.07O2 has been synthesized in P3, P2, and composite P2/P3 structures and compared with unsubstituted Na0.7Mn0.75Ni0.25O2 analogues as positive electrodes for sodium-ion batteries. The synthesis temperature was shown to provide a means of controlling the phase ratio of P2 and P3 phases. Powder diffraction measurements, high-resolution transmission electron microscopy (TEM), and selected area electron diffraction (SAED) revealed that Zn substitution enhanced the ordering of the transition metal (TM) layers. Electrochemical studies combined with XAS measurements showed that after Zn substitution, Ni activity was enhanced, while the irreversible activity of O and Mn was suppressed. Structural transformations were suppressed, and the reversibility of Zn-substituted samples on cycling was improved. Among the Zn-substituted samples, Zn–P2/P3 delivers the best electrochemical performance with an initial capacity of 121 mAh g–1 at a rate of 25 mA g–1 and 90% capacity retention after 100 cycles in half-cells. This work reveals the intrinsic correlation among cation doping, synthesis conditions, and crystal phase compositions but also provides a reliable strategy for designing high-stability composite layered cathode materials for sodium-ion batteries.
|
Jun 2026
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Diamond Proposal Number(s):
[38563]
Open Access
Abstract: The development of diverse battery chemistries demands advanced diagnostic techniques to study them. Neutron diffraction, which is sensitive to light elements and capable of distinguishing transition metals with similar electronic configurations, is well-suited to probe crystallographic transformations in battery materials and their degradation pathways. Yet its use has been limited by compromised data quality, low time resolution, and the absence of resource-efficient, reproducible, benchmarked electrochemical cells. Here, using the high-resolution cold-neutron diffractometer WISH, we demonstrate operando neutron diffraction studies of standard laboratory-scale single-layer pouch cells without build modifications, electrolyte deuteration, or isotope enrichment of the electrodes, under practical cycling conditions. This expands the battery diagnostic toolkit beyond X-rays and enables academic exploration of both established and emerging technologies, especially lithium–metal, anode-less, and lithium–sulfur batteries.
|
Mar 2026
|
|
B18-Core EXAFS
|
Diamond Proposal Number(s):
[19850, 29271]
Open Access
Abstract: Understanding the active site dynamics and redox behavior of copper species in zeolite catalysts is critical for advancing the understanding of catalytic methane-to-methanol conversion. These catalysts are also used for the selective catalytic reduction of NOx in diesel engines. Here, we present the first application of muon spin spectroscopy (μSR) to study transition metal-exchanged SSZ-13 (Cu-SSZ-13) zeolites and highlight the potential of μSR. This technique reveals unique insights into the local magnetic and electronic environments of Cu species, inaccessible via conventional spectroscopies. Temperature-dependent transverse field μSR measurements show a clear conversion of paramagnetic muonium (Mu0) to diamagnetic muon (Mu+) states, with distinct differences between Cu-loaded and pure SSZ-13 systems. This transformation is thermally activated, with Arrhenius analysis yielding activation energies of ∼3.3–5 meV, consistent with ionization processes of shallow donor states. Longitudinal field measurements confirm 2D muonium diffusion within Cu-SSZ-13 and support a model where muonium reacts with mono(μ-oxo)dicopper species, inducing comproportionation (2Cu2+ → 2Cu1.5+). DFT simulations validate this mechanism, reproducing the experimentally determined hyperfine coupling constants. At low temperatures (≤25 K), μSR also detects the onset of static magnetism in Cu clusters, consistent with Cu(II)-based multinuclear motifs. These results establish μSR as a powerful, underutilized probe for catalytic systems and provide compelling evidence for a multistep oxidation mechanism involving the initial reduction of Cu centers prior to methanol formation. This approach opens new avenues for real-time, local investigation of redox-active catalytic materials.
|
Mar 2026
|
|
I11-High Resolution Powder Diffraction
|
Haowen
Tian
,
Li
Tianyu
,
Anya S.
Mulligan
,
Jack P. G.
Tregidga
,
Matthew A.
Wright
,
Zohar
Arava
,
Chezhiyan
Aditya
,
Molleigh B.
Preefer
,
Stone
Kevin H
,
Jerry
Hu
,
Guang
Wu
,
Alicia María
Manjón-Sanz
,
Saul H.
Lapidus
,
John W.
Harter
,
Anthony K.
Cheetham
,
Ram
Seshadri
Diamond Proposal Number(s):
[36397]
Abstract: A previously unreported low-temperature phase transition in bismuth halide double perovskite Cs2AgBiCl6 is reported, thereby establishing trends in the structural ground states across Cs2NaBiCl6, Cs2AgBiCl6, and Cs2AgBiBr6. Using the combined toolkit of variable-temperature synchrotron X-ray and neutron powder diffraction, Raman spectroscopy, and density-functional theory-based electronic structure modeling, we demonstrate a cubic
𝐹𝑚3¯𝑚→
tetragonal I4/m transition upon cooling with distinct onset temperatures. Neutron powder diffraction refinements and DFT calculations assign the low-temperature phase of Cs2NaBiCl6 to I4/m, rather than the previously reported I4/mmm ground state. Cs2AgBiCl6 is also found to transform to a structure crystallizing in the I4/m space group at low temperatures. Temperature-dependent Raman data and density-functional-theory-based modeling capture the softening and freezing of octahedral tilt modes and quantify relative instabilities. Solid-state nuclear magnetic resonance spectroscopy at room temperature completes the characterization and helps underpin the subtle differences in the covalency across the compounds. Trends in the phase transition temperature Ts and tilt magnitudes emerge from coupled effects of halide identity, M(I)–site bonding character, and a mismatch between interatomic distances. These results establish the structure–dynamics–bonding framework for tuning tilt-driven instabilities in halide double perovskites.
|
Mar 2026
|
|
