I15-Extreme Conditions
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Diamond Proposal Number(s):
[36011, 39563]
Abstract: This study identifies the structural origin of giant electrostrain in samarium-doped bismuth ferrite lead titanate (0.55Bi1-xSmxFeO3–0.45PbTiO3) ceramics. A giant peak-to-peak electrostrain (∼0.5 % at 60 kV cm–1) was obtained for compositions with x = 0.20 (20Sm) during initial poling, superior to Pb(Zr,Ti)O3 based ceramics with similar phase transition temperature of 275 °C, coupled with a piezoelectric coefficient of 276 pC/N comparable with hard PZT. While 20Sm is a macroscopically pseudo-cubic relaxor in its unpoled state, an irreversible, field-induced transformation gives a tetragonal (c/a∼1.115) ferroelectric phase as revealed by in-situ poling synchrotron X-ray diffraction and confirmed by transmission electron microscopy. The field-induced domain structure of the tetragonal structure could be reversibly switched under AC field after transformation. Quantitative strain analysis confirmed that the structural transformation accounts for approximately half of the total electrostrain, with the remainder by domain switching. These results highlight the importance of field-induced structural transformations for the development of high-performance piezoelectrics.
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Sep 2026
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Terence
Tan
,
Oliver J.
Clark
,
Matthew J.
Derry
,
Renaud
Duyme
,
Guilherme Abreu
Faria
,
Robert
Farla
,
Ralf
Flaig
,
Yogal Prasad
Ghimirey
,
Anushka
Ghosh
,
Miguel A.
Gomez-Gonzalez
,
Ellen L.
Heeley
,
Anna
Herlihy
,
Annette
Kleppe
,
Paul
Millar
,
Melanie
Nentwich
,
Josh
Pickston
,
Nick
Terrill
,
Armin
Wagner
,
Andrew C.
Walters
,
Matthew
Watson
,
Philippe
Rocca-Serra
,
Susanna-Assunta
Sansone
,
Stephen P.
Collins
Open Access
Abstract: Experiment proposals at synchrotron facilities serve as the primary gateway for instrument access. They currently lack the standardized and granular topic metadata necessary for tasks such as classification and review, and, broadly speaking, reuse. This paper defines and tests the feasibility of a real-time topic classification service for experiment proposals using an open-source machine-learning model and domain experts for the evaluation phase. We applied the OpenAlex topic classification model to 5384 experiment proposals and selected 209 of them to each be independently evaluated by three domain experts to assess the performance and utility of the model. Analysis of the evaluations reveals a general consensus among the reviewers regarding the model's predictions, with a Krippendorff's alpha of 0.572. We also find that 74.2% of the proposals had at least one topic that was unanimously deemed relevant, which suggests that the model performs well enough to be used in a live setting with real-time verification. However, we do not recommend using it in automated environments without human oversight, given the proposal-based precision score of 56.0%. By aligning the data infrastructure of photon and neutron facilities with the OpenAlex ecosystem, we also lay the groundwork for the eventual inclusion of proposals and experiment reports into OpenAlex, which is necessary for a complete record of a research activity.
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Sep 2026
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[39563]
Open Access
Abstract: Lead-free dielectric capacitors require high-recoverable energy density and thermal stability under low operating fields to prevent premature breakdown. Here, we demonstrate a design strategy for high-performance lead-free dielectrics based on two key principles: selecting a highly polarizable ferroelectric matrix and engineering local polar frustration to suppress long-range order and stabilize an ergodic relaxer state. Using the (0.94Na0.5Bi0.5TiO3-0.06BaTiO3)–x(0.85NaNbO3-0.15CaTiO3) (NBT-BT-NN-CT) as an exemplar in this work, structural analyses reveal that NN-CT incorporation induces a frustrated polar structure characterized by the nanoscale coexistence of rhombohedral, tetragonal, and cubic-polymorphs. Density functional theory confirms that energetic degeneracy physically prevents the formation of stable macro-domains. The optimal composition yields wide temperature stability (±15% permittivity up to 370°C), far exceeding the X7R industrial standard, delivering a recoverable energy density of >5 J cm−3 under low field (250 kV cm−1) achieving an ultrahigh normalized energy density (Wa) of >0.020 mC cm−2, 60% improvement over conventional NBT-based counterparts in the literature (e.g., 0.012–0.015 mC cm−2). Furthermore, in situ synchrotron X-ray diffraction (<160 kV cm−1) provides strong crystallographic evidence of this dynamic structural stability, confirming the absence of irreversible field-induced phase transitions. These results establish polar frustration engineering as a transferable design principle for resilient, high-performance lead-free dielectrics.
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Aug 2026
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[30851, 36866]
Open Access
Abstract: This study maps the high-pressure crystallization landscape of meta-xylene (m-xylene) and reports the first structural characterization of a new high-pressure polymorph (Form II), obtained by direct compression of the liquid to ∼0.8 GPa at room temperature. Using single crystal X-ray diffraction and synchrotron powder diffraction, we show that Form II persists on compression to ∼3.6 GPa in neat samples. Introducing a methanol–ethanol medium enables rate-controlled polymorph selection from a fully miscible solution: slow compression yields the denser, thermodynamically stable Form I, whereas rapid compression results in the kinetically favored Form II. Maintaining Form II near 3.4 GPa for an extended period in the methanol–ethanol medium produces needle-like crystallites consistent with a distinct phase, providing evidence for a second high-pressure polymorph (Form III). On decompression to ∼0.8 GPa, Form II transforms to Form I via solvent-mediated dissolution and reprecipitation, highlighting the role of molecular mobility in reconstructive transitions. Equations of state indicate that Form I is denser than Form II up to ∼3.8 GPa, and dispersion-corrected DFT methods predict lower lattice energies for Form I across a wide range of pressures and temperatures. Collectively, these results demonstrate how pressure can be used as a powerful tool to induce crystallization in liquids and guide polymorphic outcomes, offering a framework for polymorph control and the potential for pressure-induced separation of technologically important organic liquids.
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Jun 2026
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[34932]
Open Access
Abstract: The atomic-scale structure and melting curve of liquid mercury was measured using in situ synchrotron x-ray diffraction (SXRD) at pressure and temperature (𝑝−𝑇) conditions up to 9.44(2) GPa and 651(1) K. Ab initio molecular dynamics (AIMD) simulations were employed to obtain a detailed atomistic model of the liquid structure. The results reveal a pronounced flattening, and potential maximum, in the measured melting curve between 6 and 9 GPa. The structure factors 𝑆HgHg(𝑄) and pair distribution functions 𝑔HgHg(𝑟)calculated from the AIMD simulations are in good overall agreement with the SXRD measurements under comparable reduced densities and temperatures, indicating that the atomistic structure of liquid Hg is well captured by AIMD. With increasing pressure, the principal peak in 𝑆HgHg(𝑄) shifts to higher 𝑄, with the subsidiary peak at 𝑄=2𝑘Fexperiencing a concomitant shift consistent with the increased electron density. Considering the Evans 𝑡-matrix formulation of the Ziman theory of liquid metals, the structural 𝑆(2𝑘F) term is expected to have only a weak influence on the electrical resistivity under compression. In contrast, the pressure-induced broadening and shift of the 𝑑-projected density of states towards the Fermi level is consistent with enhanced near-resonant 𝑑-electron scattering, and a corresponding increase in resistivity, analogous to the behavior of first-row transition metals. Analysis of the measured 𝑔HgHg(𝑟) functions, and AIMD trajectories in real space, indicates that the liquid structure experiences a progressive development towards simple hard-sphere-like behavior at increasing 𝑝−𝑇along the melting curve. However, topological cluster classification analysis shows that while the structural fingerprint of liquid Hg strongly resembles an effective hard-sphere system, even at the highest pressures investigated it contains more many-body motifs than expected for this simple model.
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May 2026
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I15-Extreme Conditions
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Lecheng
Zhang
,
Juncheng
Pan
,
Jiayi
Wen
,
Jiajun
Shi
,
Ziqi
Yang
,
Bing
Wang
,
Annette K.
Kleppe
,
Egor
Koemets
,
Ilkan
Calisir
,
Yizhe
Li
,
David A.
Hall
Diamond Proposal Number(s):
[34938]
Open Access
Abstract: BiFeO3-BaTiO3 (BF-BT) ceramics are important lead-free ferroelectric materials, which are attracting attention due to their high Curie temperatures. In the present study, the effects of annealing at intermediate temperatures on the structure and ferroelectric hardening effects in Ti-doped BF-BT ceramics are investigated. It is shown that enhanced ferroelectric and piezoelectric properties are obtained by air-quenching. After subsequent annealing for 200 hours at temperatures in the range from 500 to 600 °C, the ferroelectric hysteresis loops became constricted due to a strong domain stabilisation effect. The ferroelectric internal bias field increased to an outstanding value of 5 kV mm-1 in a poled-annealed specimen. Analysis of the extrinsic (domain switching) and intrinsic (lattice strain) contributions to electro-strain by in-situ x-ray diffraction indicated that domain switching is dominant in the quenched BF-BT ceramic, but the domain orientation fraction under high electric field was reduced dramatically, from approximately 80% to 25%, after annealing.
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Feb 2026
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[36011]
Open Access
Abstract: The development of high-performance lead-free piezoelectric materials has gained significant attention due to environmental concerns regarding lead toxicity. In this study, through in-situ poling synchrotron X-ray diffraction (XRD), dielectric spectroscopy, and ferroelectric measurements, we demonstrate an irreversible transition from non-ergodic relaxor behaviour to long-range ferroelectric ordering under applied electric fields in (1-x)BiFeO3 -xSrTiO3 with MnO2 addition (BF-ST-Mn).The optimal composition with x = 0.44 exhibits electrostrain of ~0.10% at 80 kV cm -1 through irreversible pseudo-cubic to rhombohedral structural transformation followed by ferroelectric domain switching. Unlike BF-ST-Nb systems that maintain pseudo-cubic symmetry, the BF-ST-Mn undergo irreversible phase transitions. Synchrotron XRD reveals initial structural transformation during the first electrical cycle, followed by domain switching in subsequent cycles. It provides promising pathways for lead-free actuator applications requiring high electrostrain at moderate driving fields.
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Jan 2026
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[30553, 31704]
Open Access
Abstract: High temperature ferroelectric ceramics have generated significant interest in recent years, from both a fundamental perspective and for practical applications as temperature-stable dielectrics or piezoelectric transducers. Particularly, BiFeO3-BaTiO3 ceramics show great promise as a replacement for lead-based materials in demanding environments. In the present study, as-sintered BiFeO3-BaTiO3 ceramics are subjected to different heat treatment conditions (annealing and quenching processes) and poling procedures to evaluate their influence on the domain configuration and functional properties. As a result, the modified 0.7BiFeO3-0.3BaTiO3 ceramics were found to exhibit a remanent polarization of 0.44 C m-2 at 100 °C, a Curie temperature of 500 °C and planar electromechanical coupling factor of 0.6 near the depolarization temperature of 480 °C after quenching at 800 °C in air; these materials show excellent potential for applications in high temperature piezoelectric transducers. In-situ temperature-dependent X-ray diffraction studies revealed unusual enhancement of the rhombohedral distortion on heating to temperatures ∼200 °C, associated with re-entrant relaxor ferroelectric behaviour. The ferroelectric domain configuration evolved from a disordered nanodomain structure in the as-sintered ceramic to a more structured herringbone-type nano-domain structure for the quenched sample, comprising a mixture of 180° and non-180° domain walls. Subsequent direct current poling led to a pronounced increase in domain size for both annealed and quenched samples, forming well-oriented lamellar domains and resulting in enhancement of ferroelectricity. High energy synchrotron X-ray diffraction experiments demonstrated a high degree of domain alignment along the electric field direction, resulting in a domain orientation fraction of ∼93% for <222>-oriented grains in the heat-treated samples. Significant enhancement of the total electrostrain upon heating from room temperature to 100 °C was attributed to a combination of the increased extrinsic domain switching contribution, due to the enhancement of spontaneous strain, together with a higher intrinsic electrostrictive lattice strain.
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Aug 2025
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[30553]
Open Access
Abstract: BiFeO3-BaTiO3 (BF-BT) solid solutions have great potential as high-temperature piezoelectric transducers and energy storage dielectrics. However, the effects of donor doping in BF-BT on the local chemical heterogeneity and corresponding control of ferroelectric properties are not well investigated. In this study, it is shown that substitution of Nb5+ for Fe3+ at a concentration of only 0.1 at% in 0.75BF-0.25BT ceramics can induce pronounced core-shell microstructural features, which are not evident for pure BF-BT ceramics or those doped with 0.1 at% Nb5+ for Ti4+. The spatial distribution of Nb, confirmed by Nano-SIMS with exceptional resolution and sensitivity, reveals the role of Nb as an aliovalent solute that inhibits chemical homogenization, stabilizing the formation of Bi-, Fe-enriched core and Ba-, Ti-enriched shell regions at high temperatures, and reducing inter-diffusion during sintering. Electric field-induced domain switching and lattice strain measurements, obtained by in-situ high-energy synchrotron X-ray diffraction, revealed the effects of elastic constraint between the core and shell regions, which degraded the dielectric, ferroelectric, and piezoelectric properties. In contrast, substitution of 0.1 at% Nb on the Ti4+ site gave rise to more homogeneous materials and induced a softening effect with enhanced functional properties. This study provides an advanced investigation into the effects of trace amounts of donor dopant in BF-BT ceramics and offers valuable insights into optimizing doping strategy to control their microstructure and functional properties.
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Mar 2025
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I15-Extreme Conditions
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Abstract: Nancyrossite, ideally FeGeO6H5, is a new hydroxyperovskite from Tsumeb. It likely formed by the oxidation and partial dehydrogenation of stottite, FeGe(OH)6, with which it is intimately associated. The structure of nancyrossite has been determined in tetragonal space group P42/n: a = 7.37382(12) Å, c = 7.29704(19) Å, V = 396.764(16) Å3, Z = 4, R1(all) = 0.034, wR2(all) = 0.051, GoF = 1.057. Empirical formulae of two crystals have almost end- member compositions, Fe3+1.01Zn0.03Ge0.98O6H5 and Fe3+1.01Zn0.04Ge0.98O6H5. Structure determination indicates that 88% Fe is ferric. The chemical formula proposed here for nancyrossite recognizes that although H atoms form OH groups, writing the formula as FeGeO(OH)5 implies that one of the six oxygen atoms is very underbonded, with a bond- valence sum of only ~1.2 v.u. As such, H in nancyrossite may have novel crystal chemistry. For example, the five H atoms may be distributed dynamically over the six O atoms, a phenomenon that would be averaged by X-ray diffraction, and so go undetected. Nancyrossite is the Ge-analogue of jeanbandyite. By analogy with nancyrossite, we propose revision of the ideal formula of jeanbandyite from FeSnO(OH)5 (Welch and Kampf, 2017) to FeSnO6H5.
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Feb 2025
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