I15-1-X-ray Pair Distribution Function (XPDF)
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Adam F.
Sapnik
,
Philip A.
Chater
,
Dean S.
Keeble
,
John S. O.
Evans
,
Federica
Bertolotti
,
Antonietta
Guagliardi
,
Lise J.
Støckler
,
Elodie A.
Harbourne
,
Anders B.
Borup
,
Rebecca S.
Silberg
,
Adrien
Descamps
,
Clemens
Prescher
,
Benjamin D.
Klee
,
Axel
Phelipeau
,
Imran
Ullah
,
Kárel G.
Medina
,
Tobias A.
Bird
,
Viktoria
Kaznelson
,
William
Lynn
,
Andrew L.
Goodwin
,
Bo B.
Iversen
,
Celine
Crepisson
,
Emil S.
Bozin
,
Kirsten M. Ø.
Jensen
,
Emma E.
Mcbride
,
Reinhard B.
Neder
,
Ian
Robinson
,
Justin S.
Wark
,
Michał
Andrzejewski
,
Ulrike
Boesenberg
,
Erik
Brambrink
,
Carolina
Camarda
,
Valerio
Cerantola
,
Sebastian
Goede
,
Hauke
Höppner
,
Oliver S.
Humphries
,
Zuzana
Konopkova
,
Naresh
Kujala
,
Thomas
Michelat
,
Motoaki
Nakatsutsumi
,
Alexander
Pelka
,
Thomas R.
Preston
,
Lisa
Randolph
,
Michael
Roeper
,
Andreas
Schmidt
,
Cornelius
Strohm
,
Minxue
Tang
,
Peter
Talkovski
,
Ulf
Zastrau
,
Karen
Appel
,
David A.
Keen
Diamond Proposal Number(s):
[39017]
Open Access
Abstract: High-quality total scattering data, a key tool for understanding atomic-scale structure in disordered materials, require stable instrumentation and access to high momentum transfers. This is now routine at dedicated synchrotron instrumentation using high-energy X-ray beams, but it is very challenging to measure a total scattering dataset in less than a few microseconds. This limits their effectiveness for capturing structural changes that occur at the much faster timescales of atomic motion. Current X-ray free-electron lasers (XFELs) provide femtosecond-pulsed X-ray beams with maximum energies of ∼24 keV, giving the potential to measure total scattering and the attendant pair distribution functions (PDFs) on femtosecond timescales. We demonstrate that this potential has been realized using the HED scientific instrument at the European XFEL and present normalized total scattering data for 0.35 Å−1 < Q < 16.6 Å−1 and their PDFs from a broad spectrum of materials, including crystalline, nanocrystalline and amorphous solids, liquids and clusters in solution. We analyzed the data using a variety of methods, including Rietveld refinement, small-box PDF refinement, joint reciprocal–real-space refinement, cluster refinement and Debye scattering analysis. The resolution function of the setup is also characterized. We conclusively show that high-quality data can be obtained from a single ∼30 fs XFEL pulse for multiple different sample types. Our efforts not only significantly increase the existing maximum reported Q range for an S(Q) measured at an XFEL but also mean that XFELs are now a viable X-ray source for the broad community of people using reciprocal-space total scattering and PDF methods in their research.
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Sep 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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Shichun
Li
,
Chao
Ma
,
Jingwei
Hou
,
Shuwen
Yu
,
Aibing
Chen
,
Juan
Du
,
Philip A.
Chater
,
Dean S.
Keeble
,
Zhihua
Qiao
,
Chongli
Zhong
,
David A.
Keen
,
Yu
Liu
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Open Access
Abstract: Crystalline metal-organic frameworks (MOFs) exhibit enormous potential application in gas separation, thanks to their highly porous structures and precise pore size distributions. Nevertheless, the inherent limitations in mechanical stability of crystalline MOFs cause challenges in processing MOF powders into bulky structures, particularly for membrane filtrations. Melt-quenched MOF glasses boast excellent processability due to liquid-like properties. However, the melting process diminishes the inherent porosity, leading to reduced gas adsorption capacities and lower gas diffusion coefficients. In this work, we demonstrated that enhancing the porosity of MOF glasses is achievable through topological engineering on the crystalline precursors. Crystalline zeolitic imidazolate frameworks (ZIFs) with large 12-membered rings pores, including AFI and CAN topology, were synthesized by using both structure-directing agents and mixed organic ligands. The large pores are partially preserved in the melt-quenched glass as evidenced by high-pressure CO2 absorption at 3000 kPa. The agAFI-[Zn(Im)1.68(bIm)0.32] glass was then fabricated into self-supported membranes, which shows high gas separation performance, for example, CO2 permeance of 3.7 × 104 GPU with a CO2/N2 selectivity of 14.8.
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Feb 2025
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I15-Extreme Conditions
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Ji
Hu
,
Alexander G.
Squires
,
Jędrzej
Kondek
,
Arthur B.
Youd
,
Pooja
Vadhva
,
Michael
Johnson
,
Partha P
Paul
,
Philip J.
Withers
,
Marco
Di Michiel
,
Dean S.
Keeble
,
Michael Ryan
Hansen
,
David O.
Scanlon
,
Alexander J. E.
Rettie
Diamond Proposal Number(s):
[35411]
Open Access
Abstract: Lithium phosphides are an emerging class of Li+ ion conductors for solid state battery applications. Despite potentially favorable characteristics as a solid electrolyte, stoichiometric crystalline Li3AlP2 has been reported to be an ionic insulator. Using a combined computational and experimental approach, we investigate the underlying reasons for this and show that ion transport can be induced via defects and structural disorder in this material. Lithium vacancies are shown to promote diffusion, and a low barrier to Li+ hopping of 0.2-0.3 eV is revealed by both simulations and experiment. However, polycrystalline pellets exhibit low ionic conductivity (≈10−8 S cm−1) at room temperature, attributed to crystalline anisotropy and the presence of resistive grain boundaries. These aspects can be overcome in nanocrystalline Li3AlP2, where ionic conductivity values approaching 10−6 S cm−1 and low electronic conductivities are achieved. This approach, leveraging both defects and structural disorder, should have relevance to the discovery of new, or previously overlooked, ion conducting materials.
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Jan 2025
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I15-1-X-ray Pair Distribution Function (XPDF)
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B. A.
Kyffin
,
R.
Di Pasquale
,
D. M.
Pickup
,
F.
Foroutan
,
I.
Abrahams
,
N.
Kanwal
,
D. S.
Keeble
,
M.
Felipe-Sotelo
,
A.
Hoxha
,
Z.
Moghaddam
,
S. J.
Hinder
,
M. A.
Baker
,
E. T.
Nery
,
D.
Carta
Diamond Proposal Number(s):
[18923]
Open Access
Abstract: Phosphate-based glasses (PBGs) are bioresorbable materials that find application in the field of controlled drug delivery and tissue engineering. The structural arrangements of the phosphate units in PBGs, along with the knowledge of how therapeutic metallic ions are embedded in the phosphate network are important in understanding the degradation and targeted release properties of these materials. Using a combination of Raman spectroscopy, high-energy X-ray diffraction and 31P and 23Na solid-state magic angle spinning nuclear magnetic resonance, the atomic structure of coacervate PBGs in the system P2O5-CaO-Na2O-MOx (M = Cu or Zn) with loadings of 2, 10 and 15 mol % of M2+ have been studied as functions of composition and calcination temperature. After drying at room temperature, the structures of the phosphate network in PBG-Cu and PBG-Zn are quite similar, with that of PBG-Zn exhibiting slightly higher connectivity. Heating at 300°C causes degradation of the polyphosphate chains, even though Q2 species remain predominant. X-ray photoelectron spectroscopy demonstrates that Cu in calcined PBGs is present in both oxidation states +1 and +2, with a predominance of the +2 state. Cu and Zn ions release data after 24 h exposure of PBGs in deionized water and cell medium DMEM show that release is proportional to their loadings. Cytotoxicity MTT assays of dissolution products of PBG-Cu/ZnX calcined at 300 °C on human osteoblast cells (MG63) and on human skin cells (HaCaTs) showed good cellular response for all compositions, indicating that PBGs have great potential for both hard and soft tissue regeneration.
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Sep 2024
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I15-1-X-ray Pair Distribution Function (XPDF)
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Open Access
Abstract: Samarium hexaboride, SmB6, is a negative thermal expansion (NTE) material whose structure is similar to other known NTE materials such as the family of Prussian blues. In the Prussian blues, NTE is due to a phonon mechanism, but we recently showed from DFT calculations that this is unlikely in SmB6 (Li et al., Phys. Chem. Chem. Phys. 2023, 25, 10749). We now report experimental X-ray diffraction and pair distribution function analysis of this material in the temperature range 20–300 K. The interatomic distances shown by both methods are consistent with the NTE instead arising from an electronic effect, by which the samarium atoms lose electrons and thus have a smaller ionic radius as the temperature increases.
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Feb 2024
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I15-1-X-ray Pair Distribution Function (XPDF)
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Haolai
Tian
,
Guanqun
Cai
,
Lei
Tan
,
He
Lin
,
Anthony E.
Phillips
,
Isaac
Abrahams
,
David A.
Keen
,
Dean S.
Keeble
,
Andy
Fiedler
,
Junrong
Zhang
,
Xiang Yang
Kong
,
Martin T.
Dove
Diamond Proposal Number(s):
[19378]
Open Access
Abstract: The lithium-ion conducting solid electrolyte Li7La3Zr2O12 has one crystalline phase that has the cubic garnet structure, and this phase has one of the highest room temperature lithium-ion conductivities of any oxide. Neutron and X-ray total scattering data, analysed by the Reverse Monte Carlo method, have been used to examine the distribution of lithium ions over a wide range of temperatures, and to explore aspects of the stability and flexibility of the basic oxide structure. We compare the results with those from supporting molecular dynamics simulations. Unlike previous work, our method requires no prior assumptions about the Li ion distribution. Using total scattering rather than solely Bragg scattering, we obtain much higher real-space resolution than previously available. The combination of X-ray and neutron scattering allows detailed characterisation of both the mobile and immobile sublattices. Only a small fraction of Li ions are mobile at any one time; diffusion occurs primarily by movement between Li2 sites via empty Li1 sites.
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Oct 2023
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[24283]
Open Access
Abstract: The main mineral component of bone is hydroxyapatite, a commonly nanocrystalline material which presents many challenges for those trying to characterize it. Here, local structure is analyzed using X-ray total scattering for synthetic samples, to enable a better understanding of the nanocrystalline nature of hydroxyapatite. Two samples were measured dynamically during heat treatment from 25 °C to 800 °C, and were analyzed using small box modelling. Analysis of sequential measurements when dwelling at key temperatures showed a significant relationship between time and temperature, indicating a process occurring more slowly than thermal expansion. This indicates a decrease in B-type CO32− substitution between 550 °C and 575 °C and an increase in A-type CO32− substitution above 750 °C. A greater understanding of local, intermediate, and long-range order of this complex biomineral during heat treatment can be of interest in several sectors, such as in forensic, biomedical and clinical settings for the study of implant coatings and bone diseases including osteoporosis and osteoarthritis.
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Aug 2022
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[18638]
Open Access
Abstract: Hydroxyapatite (HA) is a complex material, which is often nanocrystalline when found within a biological setting. This work has directly compared the structural characteristics derived from data collected using a conventional laboratory-based X-ray diffractometer with those collected from a dedicated pair distribution function (PDF) beamline at Diamond Light Source. In particular, the application of PDF analysis methods to carbonated HA is evaluated. 20 synthetic samples were measured using both X-ray diffraction (XRD) and PDFs. Both Rietveld refinement (of laboratory XRD data) and real-space refinement (of PDF data) were used to analyse all samples. The results of Rietveld and real-space refinements were compared to evaluate their application to crystalline and nanocrystalline hydroxyapatite. Significant relationships were observed between real-space refinement parameters and increasing carbonate substitution. Understanding the local order of synthetic hydroxyapatite can benefit several fields, including both biomedical and clinical settings.
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May 2022
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[22841]
Open Access
Abstract: The effect of substituting Cu by elemental additions of Ni or Co on the atomic structure of the Zr60Cu30Al10 ternary bulk metallic glass (BMG) is studied using high-energy synchrotron radiation X-ray diffraction. Analyses of the structural features in reciprocal and real space using the structure factors S(Q) and pair-distribution functions (PDF) point to an increase in the structural disorder for the Ni- or Co-bearing quaternary alloys. This is consistent with the “confusion principle” since upon alloying the initially nearly identical atomic sizes of Cu, Ni and Co diversify due to local electronic interactions. In real space, the disordering is manifested by a reduced deviation from the average particle density visible in the nearest-neighbour (NN) atomic shell structure over the complete short- and medium-range order region. Despite their similar atomic size, enthalpies of mixing with the main alloy elements and apparent disordering of the structure, the additions of Ni or Co have different effects on thermal stability of the ternary “mother” alloy.
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Apr 2022
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I15-1-X-ray Pair Distribution Function (XPDF)
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Jette K.
Mathiesen
,
Espen D.
Bøjesen
,
Jack K.
Pedersen
,
Emil T. S.
Kjær
,
Mikkel
Juelsholt
,
Susan
Cooper
,
Jonathan
Quinson
,
Andy S.
Anker
,
Geoff
Cutts
,
Dean S.
Keeble
,
Maria S.
Thomsen
,
Jan
Rossmeisl
,
Kirsten M. Ø.
Jensen
Diamond Proposal Number(s):
[20187]
Open Access
Abstract: Intermetallic nanoparticles (NPs) have shown enhanced catalytic properties as compared to their disordered alloy counterparts. To advance their use in green energy, it is crucial to understand what controls the formation of intermetallic NPs over alloy structures. By carefully selecting the additives used in NP synthesis, it is here shown that monodisperse, intermetallic PdCu NPs can be synthesized in a controllable manner. Introducing the additives iron(III) chloride and ascorbic acid, both morphological and structural control can be achieved. Combined, these additives provide a synergetic effect resulting in precursor reduction and defect-free growth; ultimately leading to monodisperse, single-crystalline, intermetallic PdCu NPs. Using in situ X-ray total scattering, a hitherto unknown transformation pathway is reported that diverges from the commonly reported coreduction disorder–order transformation. A Cu-rich structure initially forms, which upon the incorporation of Pd(0) and atomic ordering forms intermetallic PdCu NPs. These findings underpin that formation of stoichiometric intermetallic NPs is not limited by standard reduction potential matching and coreduction mechanisms, but is instead driven by changes in the local chemistry. Ultimately, using the local chemistry as a handle to tune the NP structure might open new opportunities to expand the library of intermetallic NPs by exploiting synthesis by design.
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Apr 2022
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