| 1. |
- Ahmed, Istaq, 1972, et al.
(författare)
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Effect of co-doping on proton conductivity in perovskite oxides BaZr0.9In0.05M0.05O3−δ (M = Yb3+ or Ga3+)
- 2010
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 35:12, s. 6381-6391
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Tidskriftsartikel (refereegranskat)abstract
- BaZr0.9In0.05M0.05O3-d (M ¼ Ga3+ or Yb3+) has been prepared by solid-statesynthesis route.Rietveld analysis of neutron powder diffraction data on as-prepared samples showed thatboth samples crystallise in the cubic space group Pm-3m. Scanning electron microscopyanalysis showed that the grains intheBaZr0.9In0.05Ga0.05O3-d sample were larger than the BaZr0.9In0.05Yb0.05O3-d sample. Dynamic thermogravimetric analysis indicates that the proton concentration was higher inpre-hydrated BaZr0.9In0.05Ga0.05O3-d sample (40%oftheoretical)than that of BaZr0.9In0.05Yb0.05O3-d sample (28%oftheoretical).Proton conductivity was studied on pre-hydrated samples(under both dry and wetAr atmospheres).Thebulk proton conductivities of the heating cycle of pre-hydrated BaZr0.9In0.05M0.05O3-d (M ¼ Ga3+ or Yb3+) samples were 2.1 * 10-5 S cm-1 and 1.9 * 10-4 Scm-1 at 350C, respectively.The effect of co-doping onproton conductivity was investigatedand the results are compared with single doped systems e.g. BaZr0.9M0.1O3-d (M=Ga3+, In3+ orYb3+) samples.
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| 2. |
- Biendicho, Jordi Jacas, et al.
(författare)
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In situ investigation of commercial Ni(OH)(2) and LaNi5-based electrodes by neutron powder diffraction
- 2015
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Ingår i: Journal of Materials Research. - : Springer Science and Business Media LLC. - 0884-2914 .- 2044-5326. ; 30:3, s. 407-416
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical reactions at both positive and negative electrodes in a nickel metal hydride (Ni-MH) battery during charge have been investigated by in situ neutron powder diffraction. Commercially available beta-Ni(OH)(2) and LaNi5-based powders were used in this experiment as positive and negative electrodes, respectively. Exchange of hydrogen by deuterium for the beta-Ni(OH)(2) electrode was achieved by ex situ cycling of the cell prior to in situ measurements. Neutron diffraction data collected in situ show that the largest amount of deuterium contained at the positive electrode is de-intercalated from the electrode with no phase transformation involved up to similar to 100 mA h/g and, in addition, the 110 peak width for the positive electrode increases on charge. The negative electrode of composition MmNi(3.6)Al(0.4)Mn(0.3)Co(0.7), where Mm = Mischmetal, exhibits a phase transformation to an intermediate hydride gamma phase first and then to the beta phase on charge. Unit cell dimensions and phase fractions have been investigated by Rietveld refinement of the crystal structure.
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| 3. |
- Biendicho, Jordi Jacas, et al.
(författare)
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New in-situ neutron diffraction cell for electrode materials
- 2014
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 248, s. 900-904
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Tidskriftsartikel (refereegranskat)abstract
- A novel neutron diffraction cell has been constructed to allow in-situ studies of the structural changes in materials of relevance to battery applications during charge/discharge cycling. The new design is based on the coin cell geometry, but has larger dimensions compared to typical commercial batteries in order to maximize the amount of electrode material and thus, collect diffraction data of good statistical quality within the shortest possible time. An important aspect of the design is its modular nature, allowing flexibility in both the materials studied and the battery configuration. This paper reports electrochemical tests using a Nickel-metal-hydride battery (Ni-MH), which show that the cell is able to deliver 90% of its theoretical capacity when using deuterated components. Neutron diffraction studies performed on the Polaris diffractometer using nickel metal and a hydrogen-absorbing alloy (MH) clearly show observable changes in the neutron diffraction patterns as a function of the discharge state. Due to the high quality of the diffraction patterns collected in-situ (i.e. good peak-to-background ratio), phase analysis and peak indexing can be performed successfully using data collected in around 30 min. In addition to this, structural parameters for the beta-phase (charged) MH electrode obtained by Rietveld refinement are presented. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.
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| 4. |
- Biendicho, Jordi Jacas, et al.
(författare)
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New Opportunities for Air Cathode Batteries; in-Situ Neutron Diffraction Measurements
- 2018
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Ingår i: Frontiers in energy research. - : Frontiers Media SA. - 2296-598X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Batteries with air electrodes are gaining interest as Energy Storage Systems (ESSs) for Electrical Vehicles (EVs) because of their high specific energy density. The electrochemical performance of these batteries is limited by the metallic electrode, which suffers structural transformations and corrosion during cycling that reduces the cycle life of the battery. In this context, relevant information on the discharge products may be obtained by in-situ neutron diffraction, a suitable technique to study electrodes that contain light elements or near neighbor elements in the periodic table. Case studies of MH-air and Fe-air batteries are highlighted.
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| 5. |
- Biendicho, Jordi Jacas, et al.
(författare)
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The Fluorite-Like Phase Nd5Mo3O16 +/-delta in the MoO3-Nd2O3 System: Synthesis, Crystal Structure, and Conducting Properties
- 2018
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 57:12, s. 7025-7035
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a study of the system MoO3-Nd(2)O(3)using a combination of X-ray powder diffraction (XRD), neutron powder diffraction (NPD), thermogravimetric analysis (TGA), and ac impedance spectroscopy (IS). A phase-pure material is observed at a composition of 45.5 mol % Nd2O3, which corresponds to an ideal stoichiometry of Nd5Mo3O16.5. XRD and NPD show that the crystal structure is a superstructure of the fluorite arrangement, with long-range ordering of the two cation species leading to a doubled unit cell parameter. The sample is found to be significantly oxygen deficient, i.e. Nd5Mo3O15.63(4), when it is prepared by a solid-state reaction at 1473 K in air. TGA measurements indicate that the sample loses only minimal mass on heating to 1273 K in O-2. IS studies of the mean conductivity under different atmospheres show that the sample is a mixed conductor between ambient temperature and 873 K, with a dominant electronic component at higher temperatures, as demonstrated by measurements under inert atmosphere. NPD measurements indicate that the anion vacancies are preferentially located on the O2 sites, while studies of the temperature dependence performed under an O(2)atmosphere to 1273 K show significantly anisotropic thermal parameters of the anions. Together with analysis of the total neutron scattering data, this supports a model of oxygen ions hopping between O2 positions, with a vacancy, rather than interstitial, mechanism for the anion diffusion.
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| 6. |
- Borowska-Centkowska, Anna, et al.
(författare)
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Defect structure in delta-Bi5PbY2O11.5
- 2019
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 9:17, s. 9640-9653
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Tidskriftsartikel (refereegranskat)abstract
- A detailed study of the defect structure in a di-substituted -Bi2O3 type phase, -Bi5PbY2O11.5, is presented. Using a combination of conventional Rietveld analysis of neutron diffraction data, reverse Monte Carlo (RMC) analysis of total neutron scattering data and ab initio molecular dynamics (MD) simulations, both average and local structures have been characterized. -Bi5PbY2O11.5 represents a model system for the highly conducting -Bi2O3 type phases, in which there is a higher nominal vacancy concentration than in the unsubstituted parent compound. Uniquely, the methodology developed in this study has afforded the opportunity to study both oxide-ion vacancy ordering as well as specific cation-cation interactions. Oxide-ion vacancies in this system have been found to show a preference for association with Pb2+ cations, with some evidence for clustering of these cations. The system shows a non-random distribution of vacancy pair alignments, with a preference for 100 ordering, the extent of which shows thermal variation. MD simulations indicate a predominance of oxide-ion jumps in the 100 direction.
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| 7. |
- Brant, William R, et al.
(författare)
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A large format in operando wound cell for analysing the structural dynamics of lithium insertion materials
- 2016
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 336, s. 279-285
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a large wound cell for in operando neutron diffraction (ND) from which high quality diffraction patterns are collected every 15 min while maintaining conventional electrochemical performance. Under in operando data collection conditions the oxygen atomic displacement parameters (ADPs) and cell parameters were extracted for Li0.18Sr0.66Ti0.5Nb0.5O3. Analysis of diffraction data collected under in situ conditions revealed that the lithium is located on the (0.5 0.5 0) site, corresponding to the 3c Wyckoff position in the cubic perovskite unit cell, after the cell is discharged to I V. When the cell is discharged under potentiostatic conditions the quantity of lithium on this site increases, indicating a potential position where lithium becomes pinned in the thermodynamically stable phase. During this potentiostatic step the oxygen ADPs reduce significantly. On discharge, however, the oxygen ADPs were observed to increase gradually as more lithium is inserted into the structure. Finally, the rate of unit cell expansion changed by similar to 44% once the lithium content approached similar to 0.17 Li per formula unit. A link between lithium content and degree of mobility, disorder of the oxygen positions and changing rate of unit cell expansion at various stages during lithium insertion and extraction is thus presented.
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| 8. |
- Chamoun, Mylad, et al.
(författare)
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Stannate Increases Hydrogen Evolution Overpotential on Rechargeable Alkaline Iron Electrodes
- 2017
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 164:6, s. A1251-A1257
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Tidskriftsartikel (refereegranskat)abstract
- Alkaline iron electrodes present some challenges for use in secondary batteries that are associated with low coulombic efficiency and discharge utilization. Low coulombic efficiency is correlated to the hydrogen evolution reaction that takes place during charge. In this work, we demonstrate rechargeable alkaline iron electrodes with significant capacity retention over 150 cycles with high efficiency by suppressing the hydrogen evolution with stannate. Adding stannate to the alkaline electrolyte when cycling the iron electrode drastically changes the electrochemistry. The additive brings on two advantageous attributes for the iron electrode: increased hydrogen evolution overpotential, and a flat and prolonged discharge curve at typical battery operation. These attributes were provided by a novel intermediate phase that was detected from in situ neutron diffraction measurements. This phase was only detected in situ while it decomposed ex situ, and indicated a solid solution constituted by some of the elements present in the electrode.
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| 9. |
- Haynes, R.J., et al.
(författare)
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New high temperature gas flow cell developed at ISIS
- 2009
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 251:1, s. Art. no. 012090-
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Konferensbidrag (refereegranskat)abstract
- A flow-through quartz gas cell, together with a gas flow control and monitoring system, has been designed and constructed at ISIS. This equipment allows neutron powder diffraction data to be collected on samples at temperatures up to around 1300 K when exposed to user chosen mixtures of O2, Ar, CO2, and CO. By exploiting the sensitivity of neutrons to the presence of light atoms such as oxygen, it is possible to probe the crystal structure of oxide materials as a function of oxygen partial pressures down to log 10p(O2) of about -20. The resultant structural information can then be correlated with the bulk properties of the materials, whose research and technological interests lie in fields such as energy production, storage materials, catalysis, and earth science.
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| 10. |
- Hosegood, Jane, et al.
(författare)
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Phylogenomics and species delimitation for effective conservation of manta and devil rays
- 2020
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Ingår i: Molecular Ecology. - : John Wiley & Sons. - 0962-1083 .- 1365-294X. ; 29:24, s. 4783-4796
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Tidskriftsartikel (refereegranskat)abstract
- Practical biodiversity conservation relies on delineation of biologically meaningful units. Manta and devil rays (Mobulidae) are threatened worldwide, yet morphological similarities and a succession of recent taxonomic changes impede the development of an effective conservation strategy. Here, we generate genome-wide single nucleotide polymorphism (SNP) data from a geographically and taxonomically representative set of manta and devil ray samples to reconstruct phylogenetic relationships and evaluate species boundaries under the general lineage concept. We show that nominal species units supported by alternative data sources constitute independently evolving lineages, and find robust evidence for a putative new species of manta ray in the Gulf of Mexico. Additionally, we uncover substantial incomplete lineage sorting indicating that rapid speciation together with standing variation in ancestral populations has driven phylogenetic uncertainty within Mobulidae. Finally, we detect cryptic diversity in geographically distinct populations, demonstrating that management below the species level may be warranted in certain species. Overall, our study provides a framework for molecular genetic species delimitation that is relevant to wide-ranging taxa of conservation concern, and highlights the potential for genomic data to support effective management, conservation and law enforcement strategies.
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