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67 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I15-Extreme Conditions	Acceptor doping and actuation mechanisms in Sr-doped BiFeO3BaTiO3 ceramics Ziqi Yang , Yizhe Li , Bing Wang , Juncheng Pan , Annette K. Kleppe , David Hall Journal Of Materiomics 71 DOI: 10.1016/j.jmat.2023.04.007 Diamond Proposal Number(s): [30553] Open Access Show Abstract ▼ Abstract: BiFeO3-BaTiO3 (BF-BT) ceramics are important multiferroic materials, which are attracting significant attention for potential applications in high temperature lead-free piezoelectric transducers. In the present study, the effects of Sr2+ as an acceptor dopant for Bi3+, in the range from 0 to 1.0 at%, on the structure and ferroelectric/piezoelectric properties of 0.7BiFeO3-0.3BaTiO3 ceramics were evaluated. The use of a post-sintering Ar annealing process was found to be an effective approach to reduce electrical conductivity induced by the presence of electron holes associated with reoxidation during cooling. A low Sr dopant concentration (0.3 at %) yielded enhanced ferroelectric (Pmax ~ 0.37 C m-2, Pr ~ 0.30 C m-2) and piezoelectric (d33 ~ 178 pC N-1, kp ~ 0.27) properties, whereas higher levels led to chemically heterogeneous core-shell structures and secondary phases with an associated decline in performance. The electric field-induced strain of the Sr-doped BF-BT ceramics was investigated using a combination of digital image correlation macroscopic strain measurements and in-situ synchrotron X-ray diffraction. Quantification of the intrinsic (lattice strain) and extrinsic (domain switching) contributions to the electric field induced strain indicated that the intrinsic contribution dominated during the poling process.	May 2023
I15-1-X-ray Pair Distribution Function (XPDF) I15-Extreme Conditions	Multiple local symmetries result in a common average polar axis in high-strain BiFeO3-based ceramics Ge Wang , Tengfei Hu , Wenxuan Zhu , Zhilun Lu , Annette Kleppe , Maria Diaz Lopez , Antonio Feteira , Derek C. Sinclair , Zhengqian Fu , Houbing Huang , Dawei Wang , Ian M. Reaney Physical Review Letters 130 DOI: 10.1103/PhysRevLett.130.076801 Diamond Proposal Number(s): [21714, 27500] Show Abstract ▼ Abstract: For the first time, the origin of large electrostrain in pseudocubic BiFeO 3 -based ceramics is verified with direct structural evidence backed by appropriate simulations. We employ advanced structural and microstructural characterizations of BiFeO 3 -based ceramics that exhibit large electrostrain ( > 0.4 % ) to reveal the existence of multiple, nanoscale local symmetries, dominantly tetragonal or orthorhombic, which have a common, averaged direction of polarization over larger, meso- or microscale regions. Phase-field simulations confirm the existence of local nanoscale symmetries, thereby providing a new vision for designing high-performance lead-free ceramics for high-strain actuators.	Feb 2023
B16-Test Beamline I15-Extreme Conditions	First observation of radiolytic bubble formation in unstirred nano-powder sludges and a consistent model thereof Mel O'Leary , Aliaksandr Baidak , Martyn Barnes , Thomas Donoclift , Christopher Emerson , Catarina Figueira , Oliver Fox , Annette Kleppe , Aaron Mcculloch , Darryl Messer , Robin Orr , Fred Currell Scientific Reports 11 DOI: 10.1038/s41598-021-01868-1 Diamond Proposal Number(s): [21977, 20531, 20469, 19017, 17524, 17519, 16218] Open Access Show Abstract ▼ Abstract: Experiments involving the irradiation of water contained within magnesium hydroxide and alumina nanoparticle sludges were conducted and culminated in observations of an increased yield of molecular hydrogen when compared to the yield from the irradiation of bulk water. We show that there is a relationship linking this increased yield to the direct nanoscale ionization mechanism in the nanoparticles, indicating that electron emission from the nanoparticles drives new radiative pathways in the water. Because the chemical changes in these sludges are introduced by irradiation only, we have a genuinely unstirred system. This feature allows us to determine the diffusivity of the dissolved gas. Using the measured gas production rate, we have developed a method for modelling when hydrogen bubble formation will occur within the nanoparticle sludges. This model facilitates the determination of a consistent radiolytic consumption rate coinciding with the observations of bubble formation. Thus, we demonstrate a nanoscale radiation effect directly influencing the formation of molecular hydrogen.	Nov 2021
I15-1-X-ray Pair Distribution Function (XPDF) I15-Extreme Conditions	Correlating local structure and sodium storage in hard carbon anodes: Insights from pair distribution function analysis and solid-state NMR Joshua M. Stratford , Annette K. Kleppe , Dean S. Keeble , Philip A. Chater , Seyyed Shayan Meysami , Christopher J. Wright , Jerry Barker , Maria-Magdalena Titirici , Phoebe K. Allan , Clare P. Grey Journal Of The American Chemical Society DOI: 10.1021/jacs.1c06058 Diamond Proposal Number(s): [17785, 13681] Show Abstract ▼ Abstract: Hard carbons are the leading candidate anode materials for sodium-ion batteries. However, the sodium-insertion mechanisms remain under debate. Here, employing a novel analysis of operando and ex situ pair distribution function (PDF) analysis of total scattering data, supplemented by information on the local electronic structure provided by operando 23Na solid-state NMR, we identify the local atomic environments of sodium stored within hard carbon and provide a revised mechanism for sodium storage. The local structure of carbons is well-described by bilayers of curved graphene fragments, with fragment size increasing, and curvature decreasing with increasing pyrolysis temperature. A correlation is observed between the higher-voltage (slope) capacity and the defect concentration inferred from the size and curvature of the fragments. Meanwhile, a larger lower-voltage (plateau) capacity is observed in samples modeled by larger fragment sizes. Operando PDF data on two commercially relevant hard carbons reveal changes at higher-voltages consistent with sodium ions stored close to defective areas of the carbon, with electrons localized in the antibonding π*-orbitals of the carbon. Metallic sodium clusters approximately 13–15 Å in diameter are formed in both carbons at lower voltages, implying that, for these carbons, the lower-voltage capacity is determined by the number of regions suitable for sodium cluster formation, rather than by having microstructures that allow larger clusters to form. Our results reveal that local atomic structure has a definitive role in determining storage capacity, and therefore the effect of synthetic conditions on both the local atomic structure and the microstructure should be considered when engineering hard carbons.	Aug 2021
I15-Extreme Conditions	Actuation mechanisms in mixed-phase K0.5Bi0.5TiO3-BiFeO3-PbTiO3 ceramics Yizhe Li , Peter I. Cowin , Bing Wang , Annette Kleppe , Tim Comyn , David Hall Journal Of The European Ceramic Society DOI: 10.1016/j.jeurceramsoc.2021.06.019 Diamond Proposal Number(s): [24144] Open Access Show Abstract ▼ Abstract: We report an in-situ synchrotron X-ray diffraction study of K0.5Bi0.5TiO3-BiFeO3-PbTiO3 ceramics, which exhibit a Tc of around 450 °C. The electromechanical actuation mechanisms comprise contributions from coexisting tetragonal and rhombohedral phases. The tetragonal {200} grain family exhibited the highest effective lattice strain, up to 8.2 ×10-3 at 5 kV/mm. Strong strain anisotropy in the tetragonal phase and field-induced intergranular stresses facilitate a partial transformation from tetragonal (high strain anisotropy) to rhombohedral (low strain anisotropy) at high electric field levels, with an average linear transformation strain of -1.54×10-3. The domain switching behavior was effectively enhanced in both tetragonal and rhombohedral phases after the phase transformation, due to the release of intergranular stress. This observed self-adapting mechanism in tuning intergranular stress through partial phase switching in the morphotropic KBT-BF-PT composition with large lattice distortion could also be exploited in other perovskite systems in order to achieve high performance high temperature piezoelectric ceramics.	Jun 2021
I15-Extreme Conditions	Internal resistive heating of non-metallic samples to 3000 K and >60 GPa in the diamond anvil cell Benedict J. Heinen , James W. E. Drewitt , Michael J. Walter , Charles Clapham , Fei Qin , Annette K. Kleppe , Oliver T. Lord Review Of Scientific Instruments 92 DOI: 10.1063/5.0038917 Diamond Proposal Number(s): [21972] Open Access Show Abstract ▼ Abstract: High pressure–temperature experiments provide information on the phase diagrams and physical characteristics of matter at extreme conditions and offer a synthesis pathway for novel materials with useful properties. Experiments recreating the conditions of planetary interiors provide important constraints on the physical properties of constituent phases and are key to developing models of planetary processes and interpreting geophysical observations. The laser-heated diamond anvil cell (DAC) is currently the only technique capable of routinely accessing the Earth’s lower-mantle geotherm for experiments on non-metallic samples, but large temperature uncertainties and poor temperature stability limit the accuracy of measured data and prohibits analyses requiring long acquisition times. We have developed a novel internal resistive heating (IRH) technique for the DAC and demonstrate stable heating of non-metallic samples up to 3000 K and 64 GPa, as confirmed by in situ synchrotron x-ray diffraction and simultaneous spectroradiometric temperature measurement. The temperature generated in our IRH-DAC can be precisely controlled and is extremely stable, with less than 20 K variation over several hours without any user intervention, resulting in temperature uncertainties an order of magnitude smaller than those in typical laser-heating experiments. Our IRH-DAC design, with its simple geometry, provides a new and highly accessible tool for investigating materials at extreme conditions. It is well suited for the rapid collection of high-resolution P–V–T data, precise demarcation of phase boundaries, and experiments requiring long acquisition times at high temperature. Our IRH technique is ideally placed to exploit the move toward coherent nano-focused x-ray beams at next-generation synchrotron sources.	Jun 2021
NONE-No attached Diamond beamline	Kernowite, Cu2Fe(AsO4)(OH)4⋅4H2O, the Fe 3+ -analogue of liroconite from Cornwall, UK M. S. Rumsey , M. D. Welch , J. Spratt , A. K. Kleppe , M. Števko Mineralogical Magazine DOI: 10.1180/mgm.2021.40 Show Abstract ▼ Abstract: The occurrence, chemical composition and structural characterization of the new mineral 3+ kernowite, ideally Cu2Fe(AsO4)(OH)4·4H2O, the Fe3+ -analogue of lirconite Cu2Al(AsO4)(OH)4·4H2O, are described. Kernowite occurs on specimens likely sourced from the Wheal Gorland mine, St Day, Cornwall, U.K in the cavities of a quartz-gossan rich in undifferentiated micro-crystalline grey sulphides and poorly crystalline arsenic phases including both pharmacosiderite and olivenite group minerals. The average composition of kernowite determined from several holotype fragments by electron microprobe analysis is Cu1.88(Fe0.79Al0.09)Σ0.88(As1.12O4)(OH)4·3.65H2O. The structure of kernowite has been determined in monoclinic space group I2/a (a non-standard setting of C2/c) by single-crystal X-ray diffraction to R1 = 0.025, wR2 = 0.051, Goodness-of-fit = 1.112. Unit-cell parameters from SCXRD are a = 12.9243(4)Å, b = 7.5401(3)Å, c = 10.0271(3)Å, Beta = 91.267(3), V = 976.91(6)Å3 (Z = 4). The chemical formula of this crystal indicated by SCXRD from refined site-scattering is Cu2(Fe3+0.84(1)Al0.16)AsO4(OH)4·4H2O. The network of hydrogen-bonding has been determined and is similar to that reported for liroconite from Wheal Gorland by Plumhoff et al. (2020).	May 2021
I15-Extreme Conditions	In situ poling X-ray diffraction studies of lead-free BiFeO3-SrTiO3 ceramics Zhilun Lu , Ge Wang , Linhao Li , Yuhe Huang , Antonio Feteira , Weichao Bao , Annette K. Kleppe , Fangfang Xu , Dawei Wang , Ian M. Reaney Materials Today Physics 71 DOI: 10.1016/j.mtphys.2021.100426 Diamond Proposal Number(s): [21714] Open Access Show Abstract ▼ Abstract: The origin of the large electrostrain in BiFeO3-BaTiO3 (BF-BT) ceramics is controversial and has been attributed to either a field-induced transition to a long-range ferroelectric (FE) state or to multi-symmetry, polar nanoregions within a pseudocubic matrix whose vectors approximately align with the direction of the applied field. The (1-x)BiFeO3-xSrTiO3 (BF-xST) solid solution is structurally and microstructurally similar to BF-BT and provides a further case study to assess the origin of electrostrain. In BF-xST, electrostrain is optimised at x = 0.4 (0.15%) which zero field, room temperature full-pattern X-ray diffraction (XRD) Rietveld refinement and scanning/transmission electron microscopy suggest is composed of 15% rhombohedral (R) cores, surrounded by 85% pseudocubic (PC) shells. In-situ poling synchrotron XRD revealed that all peaks remained singlet and exhibited no change in full width half maximum up to 100 kV cm-1, confirming the absence of long-range FE order and the retention of short-range polar order, despite the large applied field. Strain anisotropy (calculated from individual peaks) of ε220 > ε111 > ε200 and the associated strain orientation distribution however, indicate the existence of local orthorhombic (O), rhombohedral (R) and tetragonal (T) symmetries. The data therefore imply the existence under poling of multi-symmetry polar nanoregions in BF-0.4ST rather than a long FE phase, supporting the model described by Wang and co-workers (2019) for BF-BT compositions.	May 2021
I15-Extreme Conditions	High-pressure neutron powder diffraction study of ε-CL-20: A gentler way to study energetic materials Sumit Konar , Steven Hunter , Carole A. Morrison , Paul L. Coster , Helen Maynard-Casely , Jonathan G. Richardson , William G. Marshall , Annette Kleppe , Stewart F. Parker , Colin R. Pulham The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.0c09967 Diamond Proposal Number(s): [4631, 6707] Show Abstract ▼ Abstract: High-pressure studies have been performed on the ε-form of the powerful explosive CL-20. Hydrostatic compression over the pressure range 0–12 GPa has been monitored using synchrotron X-ray powder diffraction. The potential effects of X-ray radiation damage were observed and circumvented through a follow-up compression study over the pressure range 0–7 GPa using neutron powder diffraction. This second study revealed smooth compression behavior, and the absence of any phase transitions. Intermolecular interaction energies as obtained using PIXEL calculations did not show any discontinuity upon the application of pressure. An isothermal equation of state has been determined, and the high-pressure response is supported by dispersion-corrected density functional theory calculations. Inelastic neutron scattering (experimental and simulated) spectra for the ε-form are in excellent agreement.	Dec 2020
I15-Extreme Conditions	Mechanism of enhanced energy storage in AgNbO3-based lead-free antiferroelectrics Zhilun Lu , Weichao Bao , Ge Wang , Shikuan Sun , Linhao Li , Jinglei Li , Huijing Yang , Hongfen Ji , Antonio Feteira , Dejun Li , Fangfang Xu , Annette K. Kleppe , Dawei Wang , Shi-Yu Liu , Ian M. Reaney Nano Energy DOI: 10.1016/j.nanoen.2020.105423 Diamond Proposal Number(s): [21714] Open Access Show Abstract ▼ Abstract: The mechanisms underpinning high energy storage in lead-free Ag1-3xNdxTayNb1-yO3 antiferroelectric (AFE) ceramics have been investigated. Rietveld refinements of in-situ synchrotron X-ray data reveal that the structure remains quadrupled and orthorhombic under electric field (E) but adopts a non-centrosymmetric space group, Pmc21, in which the cations exhibit a ferrielectric configuration. Nd and Ta doping both stabilise the AFE structure, thereby increasing the AFE-ferrielectric switching field from 150 to 350 kV cm-1. Domain size and correlation length of AFE/ferrielectric coupling reduce with Nd doping, leading to slimmer hysteresis loops. Pmax is optimised through A-site aliovalent doping which also decreases electrical conductivity, permitting the application of a larger E. These effects combine to enhance energy storage density to give Wrec = 6.5 J cm-3 for Ag0.97Nd0.01Ta0.20Nb0.80O3.	Sep 2020

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