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There are five filter-analyzer neutron spectrometers available worldwide for scientists to use in order to measure the vibrational density of states in various samples. While Taipan, the thermal spectrometer, has been operated as a triple-axis spectrometer at the Australian Centre for Neutron Scattering since 2010, a beryllium filter analyzer spectrometer was added in 2016. Due to the complex nature of the data post-processing, it has thus far been impossible to fully treat experimental data from scientific measurements taken over the last five years. We have successfully created a robust method of treating data from the Taipan filter-analyzer and present the method on three different samples. The data-treatment process includes correction for the non-linear energy variation of a particular monochromator, removal of higher-order wavelength contamination, and estimation of low-energy multiple-scattering. The steps described here can be utilized by all users of the Australian Nuclear Science and Technology Organisation "Be-filter"—past, present, and future. [ABSTRACT FROM AUTHOR]

Abstract: The interdependent effects of temperature and guest uptake on the structure of the ultramicroporous metal–organic framework [Cu3(cdm)4] (cdm=C(CN)2(CONH2)−) were explored in detail by using in situ neutron scattering and density functional theory calculations. The tetragonal lattice displays an anisotropic thermal response related to a hinged “lattice‐fence” mechanism, unusual for this topology, which is facilitated by pivoting of the rigid cdm anion about the Cu nodes. Calculated pore‐size metrics clearly illustrate the potential for temperature‐mediated adsorption in ultramicroporous frameworks due to thermal fluctuations of the pore diameter near the value of the target guest kinetic diameter, though in [Cu3(cdm)4] this is counteracted by a competing contraction of the pore with increasing temperature as a result of the anisotropic lattice response. [ABSTRACT FROM AUTHOR]

While some works in this Special Collection highlight recent developments in the in situ and (in) operando characterisation techniques that have been successfully applied for more than a decade, such as X-ray and neutron diffraction and X-ray spectroscopy ( B Liang et al b ., B Wu et al b ., B Gustafsson et al b ., B Chien et al b ., B Lebens-Higgins b ), some new rising methods such as acoustic emission methods ( B Schweidler et al b .), This B Special Collection b concerns the recent evolution of methods and techniques used to understand the function of such materials, a necessary step towards the rational design of new energy storage technology with improved performance characteristics. Such characterisation methods would ideally give information about energy storage materials and components that are performing as they would in the operating device, as close to real-world applied conditions and with as much detail as possible. [Extracted from the article]

A system for positioning powder samples in top-loading cryofurnaces during neutron scattering experiments, while facilitating the successive delivery of gas doses at set temperatures to the sample, has been designed and tested. The positioning system is compatible with a Hiden Isochema IMI instrument as a gas-dosing platform, enabling gases to be delivered to the sample through a centrally located and thermally stabilized capillary line and valve. The positioning system separates into an upper and a lower section, with the lower section enabling the sample to be isolated and inserted into a glove box. This work describes the system using example neutron powder diffraction results obtained with this system in closed-cycle cryofurnaces. [ABSTRACT FROM AUTHOR]

The dissimilar lattice-evolution of the isostructural layered Li(Ni,Co,Al)O2 (NCR) and Li(Ni,Co,Mn)O2 (CGR) cathodes in commercial lithium-ion batteries during overcharging/discharging was examined using operando neutron powder-diffraction. The stacking axis (c parameter) of both cathodes expands on initial lithiation and contracts on further lithiation. Although both the initial increase and later decrease are smaller for the CGR cathode, the overall change between battery charged and discharged states of the c parameter is larger for the CGR (1.29%) than for the NCR cathode (0.33%). We find these differences are correlated to the transition metal to oxygen bond (as measured through the oxygen positional-parameter) which is specific to the different cathode chemistries. Finally, we note the formation of and suggest a model for a LiCx intermediate between graphite and LiC12 in the anode of both batteries. [ABSTRACT FROM PUBLISHER]

Abstract: The structures of the defect pyrochlores AAl0.33W1.67O6 where A=K, Rb or Cs have been investigated using X-ray and neutron powder diffraction methods as well as the ab initio modelling program VASP. The three cubic pyrochlores exhibit a non-linear increase in lattice parameter with respect to ionic radius of the A cation as a consequence of displacive disorder of the A-type cations. Solid state 27Al MAS NMR studies of this pyrochlore system reveal shifts in the δ∼21–22ppm range that are indicative of pseudo-5 coordinate Al environments and emanate from distorted Al octahedral with one abnormally long Al–O bond. Solid state 39K, 85Rb, 87Rb and 133Cs MAS and static NMR studies reflect the local cation disorder demonstrated in the structural studies. [Copyright &y& Elsevier]

In this work lithium self-diffusion in the model lithium garnet oxide Li 5 La 3 Ta 2 O 12 was investigated by combining quasi-elastic neutron scattering experiments and molecular dynamics simulation. The Q -dependence of the quasi-elastic broadening measured experimentally and of the mean relaxation rate of lithium calculated by molecular dynamics simulations were both well described by the Singwi-Sjölander diffusion model. This model describes lithium nuclei that undergo diffusion via a jump-type mechanism consisting of a distribution of jumps with a mean square jump distance and residence time. The extracted mean jump length is consistent with a jump between tetrahedral (24 d ) to octahedral (48 g and 96 h ) sites within the I a 3 ¯ d symmetry structure and the residence time of Li at these sites obeys an Arrhenius relation from ~ ps timescales at 1100 K to the ~ ns range at 400 K. This result supports a lithium diffusion mechanism in which jumps are more frequent (smaller residence time) and shorter at higher temperature. The self-diffusivities of Li from both experiment and calculation were in good agreement, but deviations from those previously measured using nuclear magnetic resonance and muon spin relaxation were observed and discussed. Analysis of stretching parameter describing the relaxation of lithium calculated by molecular dynamics indicated that Li motion is more cooperative at shorter length scales, below ~ 4.4 Å, which corresponds to the distance between octahedral sites across the tetrahedral site. [ABSTRACT FROM AUTHOR]

Abstract: The structure of the defect pyrochlore NaW2O6+δ ·nH2−z O after ion exchange with K, Rb, Sr or Cs for Na has been investigated using thermal analysis, solid-state nuclear magnetic resonance, laboratory X-ray and neutron diffraction methods. Neutron diffraction studies show that both the A-type cations (Na+, K+, Rb+, and/or Cs+) and the water molecules reside within the channels that form in the 111 direction of the W2O6 framework and that these strongly interact. The analytical results suggest that the water and A-type cations compete for space in the tunnels within the W2O6 pyrochlore framework, with the total number of water molecules and cations being approximately constant in the six samples investigated. The interplay between the cations and water explains the non-linear dependence of the a lattice parameter on the choice of cation. It appears that the ion-exchange capacity of the material will be controlled by the amount of water initially present in the sample. [Copyright &y& Elsevier]