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An extended nitro-functionalised 1,2,4-triazole ligand has been used to induce considerable lattice distortion in a 2-D Hofmann framework material via competing supramolecular interactions. Single crystal X-ray diffraction analyses on [Fe3(N-cintrz)6(Pd(CN)4)3]·6H2O (N-cintrz: (E)-3-(2-nitrophenyl)acrylaldehyde) reveal a substantial deviation from a regular Hofmann structure, in particular as the intra- and inter-layer contacts are dominated by hydrogen-bonding interactions rather than the typical π-stacking arrays. Also, the 2-D Hofmann layers show an assortment of ligand conformations and local FeII coordination environments driven by the optimisation of competing supramolecular contacts. Temperature-dependent magnetic susceptibility measurements reveal a two-step spin crossover (SCO) transition. Variable temperature structural analyses show that the two crystallographically distinct FeII centres, which are arranged in stripes (2 : 1 ratio) within each Hofmann layer, undergo a cooperative HS ↔ HS/LS ↔ LS (HS = high spin, LS = low spin) transition without periodic spin-state ordering. The mismatch between crystallographic (2 : 1) and spin-state (1 : 1) periodicity at the HS : LS step provides key insight into the competition (frustration) between elastic interactions and crystallographically driven order. [ABSTRACT FROM AUTHOR]

Invited for this month's cover is the group of Daniel R. Sørensen at the University of Aarhus (Denmark) and at the University of Lund (Sweden). The cover picture shows a battery cell designed for in operando neutron powder diffraction. The picture seeks to illustrate the experiment process where lithium ions are moving into the crystal structure of the battery cathode during discharge. This leads to changes in the crystal structure that are very important to understand for optimizing the battery materials. These structural changes are probed in operando by neutron powder diffraction, and neutrons are especially suited for probing the location of Li‐ion compared with similar techniques such as X‐ray diffraction. The beauty of using neutrons is also that their penetrating power allows for investigating the battery without the need for windows of any kind. Read the full text of their Research Article at 10.1002/cmtd.202200046. [ABSTRACT FROM AUTHOR]

The ability to directly track the charge carrier in a battery as it inserts/extracts from an electrode during charge/discharge provides unparalleled insight for researchers into the working mechanism of the device. This crystallographic-electrochemical information can be used to design new materials or modify electrochemical conditions to improve battery performance characteristics, such as lifetime. Critical to collecting operando data used to obtain such information in situ while a battery functions are X-ray and neutron diffractometers with sufficient spatial and temporal resolution to capture complex and subtle structural changes. The number of operando battery experiments has dramatically increased in recent years, particularly those involving neutron powder diffraction. Herein, the importance of structure-property relationships to understanding battery function, why in situ experimentation is critical to this, and the types of experiments and electrochemical cells required to obtain such information are described. For each battery type, selected research that showcases the power of in situ and operando diffraction experiments to understand battery function is highlighted and future opportunities for such experiments are discussed. The intention is to encourage researchers to use in situ and operando techniques and to provide a concise overview of this area of research. [ABSTRACT FROM AUTHOR]

Thestructure of the nanoporous metal–organic frameworkCu3(BTC)2(BTC = 1,3,5-benzenetricarboxylate)with a variety of molecular guests was studied in situusing single crystal X-ray diffraction. By collecting crystal structuredata for a series of guests within the same host crystal, insightsinto the molecular interactions underpinning guest adsorption processeshave been gained. Adsorption behaviors are influenced strongly byboth enthalpic and entropic thermodynamic, as well as interpore steric(size-exclusion) effects, and we note correlations between guest attributesand these effects. Vapor adsorption measurements revealed a guestuptake capacity inversely proportional to guest size. Correspondingly,structural results show that guests reside in the smallest pores accessibleto them. Interpore steric effects for larger guests cause these tobe excluded from the smallest pores, and this corresponds to lowertotal uptake. Both hydrophilic and lipophilic small guests adsorbfavorably into the 5 Å diameter smallest pore of the material,with the number of guests in these pores dependent on guest size andtheir location, in turn dependent upon both guest–guest interactionsand competition between hydrogen-bonding interactions at the aperturesof the smallest pore and lipophilic interactions at the center ofthe smallest pore. Hydrophilic guests with lone electron pairs interactpreferentially with the coordinatively unsaturated Cu sites of thedesolvated framework, with the number of these depending on stericinteractions between neighboring bound guests and guest flexibility.Guest coordination at the Cu sites has a significant effect on theframework structure, increasing the Cu···Cu distancein the dinuclear unit, with the Cu3(BTC)2unitcell being smaller when guests that do not coordinate with the Cuare present, and in the case of cyclohexane, smaller than for thedesolvated framework. Overall, our comprehensive structural studyreconciles Cu3(BTC)2adsorption properties withthe underlying guest–host and guest–guest interactionsthat gives rise to these. [ABSTRACT FROM AUTHOR]

Graphite has been widely used as a negative electrode material in lithium-ion batteries, and recently it has attracted attention for its use in potassium-ion batteries. In this study, the first in situ X-ray diffraction characterisation of a K/graphite electrochemical cell is performed. Various graphite intercalation compounds are found, including the stage three KC36 and stage one KC8 compounds, along with the disappearance of the graphite during the potassiation process. These results show new insights on the non-equilibrium states of potassium-ion intercalation into graphite in K/graphite electrochemical cells. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including powder diffraction, X-ray diffraction, and X-ray fluorescence.

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]

Yeelimite, Ca4[Al6O12]SO4, is outstanding as an aluminatesodalite, being the framework ofthese type of materials flexible and dependent on ion sizes and anionordering/disordering. On the other hand, yeelimite is also importantfrom an applied perspective as it is the most important phase in calciumsulfoaluminate cements. However, its crystal structure is not wellstudied. Here, we characterize the room temperature crystal structureof stoichiometric yeelimite through joint Rietveld refinement usingneutron and X-ray powder diffraction data coupled with chemical soft-constraints.Our structural study shows that yeelimite has a lower symmetry thanthat of the previously reported tetragonal system, which we establishto likely be the acentric orthorhombic space group Pcc2, with a √2a × √2a × a superstructure basedon the cubic sodalite structure. Final unit cell values were a= 13.0356(7) Å, b= 13.0350(7) Å,and c= 9.1677(2) Å. We determine several structuresusing density functional theory calculations, with the lowest energystructure being Pcc2 in agreement with our experimentalresult. Yeelimite undergoes a reversible phase transition to a higher-symmetryphase which has been characterized to occur at 470 °C by thermodiffractometry.The higher-symmetry phase is likely cubic or pseudocubic possessingan incommensurate superstructure, as suggested by our theoreticalcalculations which show a phase transition from an orthorhombic toa tetragonal structure. Our theoretical study also predicts a pressure-inducedphase transition to a cubic structure of space group I43m. Finally, we show thatour reported crystal structure of yeelimite enables better mineralogicalphase analysis of commercial calcium sulfoaluminate cements, as shownby RFvalues for this phase, 6.9% and 4.8% for the previouslypublished orthorhombic structure and for the one reported in thisstudy, respectively. [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]

Ca4[Al6O12]SO4 (yeelimite) is prepared by solid state reaction of CaCO3, Al2O3, and CaSO4 (1300 °C, 4 h, slow cooling). [ABSTRACT FROM AUTHOR]