Search Results

You searched for all publications:

with publication states 'Published (Approved)'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

2 items found (0 items not approved), displaying all items.1

Instruments / Technical Area	Publication Details	Published	Actions
I15-1-X-ray Pair Distribution Function (XPDF)	Local structure and lithium-ion diffusion pathway of cubic Li7La3Zr2O12 studied by total scattering and the Reverse Monte Carlo method 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 Journal Of Materials Chemistry A 46 DOI: 10.1039/D3TA04495E Diamond Proposal Number(s): [19378] Open Access Show Abstract ▼ 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.	Oct 2023
B18-Core EXAFS	Transition metal cations on the move: simultaneous operando X-ray absorption spectroscopy and X-ray diffraction investigations during Li uptake and release of a NiFe2O4/CNT composite Stefan Permien , Tobias Neumann , Sylvio Indris , Gero Neubüser , Lorenz Kienle , Andy Fiedler , Anna-Lena Hansen , Diego Gianolio , Thomas Bredow , Wolfgang Bensch Physical Chemistry Chemical Physics 9 DOI: 10.1039/C8CP02919A Diamond Proposal Number(s): [10411] Show Abstract ▼ Abstract: We report on results of a comprehensive investigation on reaction mechanisms occurring during Li uptake and release of the composite NiFe2O4/CNT. Operando X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) data collected simultaneously using one in situ cell allowed thorough elucidation of structural and electronic alterations happening during Li uptake. From the beginning of Li uptake, the Bragg intensity of the spinel reflections decreases which can be explained by reduction of Fe3+ ions and simultaneous movement of the Fe2+ cations from tetrahedral 8a to empty octahedral 16c sites. The reduction of Fe3+ is clearly evidenced by XAS. The occupation of tetrahedral sites by Li+ can be excluded based on results of density functional theory calculations. Increasing the Li content leads to formation of a new crystalline phase resembling a monoxide with a NaCl-like structure. The appearance of the new phase is accompanied by a steady decrease of the sizes of coherently scattering domains of the spinel and a growth of the domains of the monoxide phase. After uptake of about 2.5 Li per NiFe2O4, all Fe3+ cations are reduced to Fe2+ and the tetrahedral 8a sites are empty (XAS spectra). Careful Rietveld refinements of X-ray powder patterns demonstrate that the tetrahedral 8a site is successively depleted with increasing Li content. Interestingly, the occupancy of the octahedral 16d site is also slightly reduced. Increasing the Li content beyond 2.5 Li/NiFe2O4 leads to successive reduction of the cations to very small metal particles embedded in a Li2O matrix (as evidenced by 7Li MAS NMR investigations). During Li release metallic Ni and Fe are reoxidized to Ni2+ resp. Fe3+. The cycling stability of NiFe2O4/CNT is significantly improved compared to pure NiFe2O4 or a mechanical mixture of NiFe2O4 and CNTs.	Jun 2018

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User