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Instruments / Technical Area	Publication Details	Published
I11-High Resolution Powder Diffraction	Compositional nanodomain formation in hybrid formate perovskites Edwina A. Donlan , Hanna L. B. Bostroem , Harry S. Geddes , Emily M. Reynolds , Andrew L. Goodwin Chem. Commun. 309 DOI: 10.1039/C7CC06928F Diamond Proposal Number(s): [13284] Show Abstract ▼ Abstract: We report the synthesis and structural characterisation of three mixed-metal formate perovskite families [C(NH2)3]CuxM1−x(HCOO)3 (M = Mn, Zn, Mg). Using a combination of infrared spectroscopy, non-negative matrix factorization, and reverse Monte Carlo refinement, we show that the Mn- and Zn-containing compounds support compositional nanodomains resembling the polar nanoregions of conventional relaxor ferroelectrics. The M = Mg family exhibits a miscibility gap that we suggest reflects the limiting behaviour of nanodomain formation.	Sep 2017
I11-High Resolution Powder Diffraction	Compositional inhomogeneity and tuneable thermal expansion in mixed-metal ZIF-8 analogues Adam F. Sapnik , Harry S. Geddes , Emily M. Reynolds , Hamish H.-m. Yeung , Andrew L. Goodwin Chemical Communications 13 DOI: 10.1039/C8CC04172E Diamond Proposal Number(s): [13284] Show Abstract ▼ Abstract: We study the structural and thermomechanical effects of cation substitution in the compositional family of metal–organic frameworks Zn1−xCdx(mIm)2 (HmIm = 2-methylimidazole). We find complete miscibility for all compositions x, with evidence of inhomogeneous distributions of Cd and Zn that in turn affect framework aperture characteristics. Using variable-temperature X-ray powder diffraction measurements, we show that Cd substitution drives a threefold reduction in the magnitude of thermal expansion behaviour. We interpret this effect in terms of an increased density of negative thermal expansion modes in the more flexible Cd-rich frameworks.	Aug 2018
I15-1-X-ray Pair Distribution Function (XPDF)	Non-equilibrium metal oxides via reconversion chemistry in lithium-ion batteries Xiao Hua , Phoebe K. Allan , Chen Gong , Philip A. Chater , Ella M. Schmidt , Harry S. Geddes , Alex W. Robertson , Peter G. Bruce , Andrew L. Goodwin Nature Communications 12 DOI: 10.1038/s41467-020-20736-6 Diamond Proposal Number(s): [22115] Open Access Show Abstract ▼ Abstract: Binary metal oxides are attractive anode materials for lithium-ion batteries. Despite sustained effort into nanomaterials synthesis and understanding the initial discharge mechanism, the fundamental chemistry underpinning the charge and subsequent cycles—thus the reversible capacity—remains poorly understood. Here, we use in operando X-ray pair distribution function analysis combining with our recently developed analytical approach employing Metropolis Monte Carlo simulations and non-negative matrix factorisation to study the charge reaction thermodynamics of a series of Fe- and Mn-oxides. As opposed to the commonly believed conversion chemistry forming rocksalt FeO and MnO, we reveal the two oxide series topotactically transform into non-native body-centred cubic FeO and zincblende MnO via displacement-like reactions whose kinetics are governed by the mobility differences between displaced species. These renewed mechanistic insights suggest avenues for the future design of metal oxide materials as well as new material synthesis routes using electrochemically-assisted methods.	Jan 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Revisiting metal fluorides as lithium-ion battery cathodes Xiao Hua , Alexander S. Eggeman , Elizabeth Castillo-martinez , Rosa Robert , Harry S. Geddes , Ziheng Lu , Chris J. Pickard , Wei Meng , Kamila M. Wiaderek , Nathalie Pereira , Glenn G. Amatucci , Paul A. Midgley , Karena W. Chapman , Ullrich Steiner , Andrew L. Goodwin , Clare Grey Nature Materials 22 DOI: 10.1038/s41563-020-00893-1 Diamond Proposal Number(s): [17315] Show Abstract ▼ Abstract: Metal fluorides, promising lithium-ion battery cathode materials, have been classified as conversion materials due to the reconstructive phase transitions widely presumed to occur upon lithiation. We challenge this view by studying FeF3 using X-ray total scattering and electron diffraction techniques that measure structure over multiple length scales coupled with density functional theory calculations, and by revisiting prior experimental studies of FeF2 and CuF2. Metal fluoride lithiation is instead dominated by diffusion-controlled displacement mechanisms, and a clear topological relationship between the metal fluoride F− sublattices and that of LiF is established. Initial lithiation of FeF3 forms FeF2 on the particle’s surface, along with a cation-ordered and stacking-disordered phase, A-LixFeyF3, which is structurally related to α-/β-LiMn2+Fe3+F6 and which topotactically transforms to B- and then C-LixFeyF3, before forming LiF and Fe. Lithiation of FeF2 and CuF2 results in a buffer phase between FeF2/CuF2 and LiF. The resulting principles will aid future developments of a wider range of isomorphic metal fluorides.	Jan 2021

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