The structural phase transition accompanied by a Jahn–Teller switch has been studied over a range of H/D ratios in (NH4)2[Cu(H2O)6](SO4)2 (ACTS). In particular, single-crystal neutron diffraction investigations of crystals with deuteration in the range 50 to 82% are shown to be consistent with previous electron paramagnetic resonance (EPR) experiments exhibiting a phase boundary at 50% deuteration under ambient pressure. Polycrystalline samples show that the two phases can co-exist. In addition, single-crystal neutron and polycrystalline X-ray diffraction pressure experiments show a shift to lower pressure at 60% deuteration versus previous measurements at 100% deuteration.

A bent Bragg–Laue monochromator (BLM) is proposed for high-energy X-ray (∼25–60 keV) beamlines. The BLM has the unique feature of bi-directional focusing. A sagittally bent Laue crystal can focus the large horizontal fan of a bending magnet or wiggler source. A meridionally bent Bragg crystal focuses the beam vertically and corrects for the anticlastic bending effects of the Laue crystal. This monochromator geometry relies on the crystal orientations being optimized. It is shown that the focusing condition and Rowland condition can be simultaneously satisfied at a given energy. Detailed ray tracings indicate that a BLM can provide similar energy resolution and higher flux density compared to a sagittally bent double-Laue monochromator configuration. A prototype BLM with a symmetric Bragg crystal and an asymmetric Laue crystal was tested. Matching of the bend radii of the two crystals in the meridional direction was demonstrated. In general, the horizontal acceptance of the sagittally bent Laue crystal is limited by the large curvature. This horizontal BLM acceptance could be increased by translating the Laue crystal along its sagittal bending axis.

Results of DC magnetization and x-ray diffraction measurements under hydrostatic pressure are reported for the CdCr2S4 spinel compound. Magnetization measurements were performed in a polycrystalline sample up to 14 kbar in the 20-220 K temperature range. At low applied magnetic fields an anomalous susceptibility behavior, associated to magnetic clusters, persists up to 14 kbar. X-ray synchrotron diffraction spectra acquired under pressure show a strong linear correlation between the variation of lattice parameters under pressure and the variation of the Cr-Cr distance. In contrast, the S-Cr-S angles remain constant. Clearly, the CdCr2S4 magnetic properties are strongly sensitive to pressure variations and the Cr local distortions observed in this compound promote a competition between direct antifer-romagnetic and super-exchange ferromagnetic interactions within such short-range magnetic clusters. (C) 2017 Elsevier B.V. All rights reserved.

A series of photomagnetic coordination polymer core-shell heterostructures, based on the light-switchable Prussian blue analogue RbaCob[Fe(CN)(6)](c)center dot mH(2)O (RbCoFe-PBA) as the core and the ferromagnetic KjNik[Cr(CN)(6)](l)center dot nH(2)O (KNiCr-PBA) as the shell, was studied using powder X-ray diffraction, down to 100 K, and magnetometry, down to 2 K, to investigate the influence of the shell thickness on light-induced magnetization changes and gain insight into the mechanism. The core material is known to undergo a charge-transfer induced spin transition (CTIST), and synchrotron powder diffraction was used to monitor structural changes in both the core and the shell associated with the thermally and optically induced CTIST of the core. Significant lattice contraction in the RbCoFe-PBA core upon cooling through the high-spin to the low-spin state transition near similar to 260 K induces strain on the KNiCr-PBA shells. This lattice strain in the shell can be relieved either by thermal cycling back to high temperature or by using light to access the metastable high-spin state of the core at low temperature. The different extents of strain in the KNiCr-PBA shell are reflected in low-temperature, low-field magnetization versus temperature data in the light and dark states. A broader magnetic transition at T-c approximate to 70 K in the dark state relative to the light state reflects the greater dispersion of nearest-neighbor contacts and exchange energies induced by the structural distortions of the strained state. Analyses for different shell thicknesses, coupled with high-field magnetization data, support a mechanism whereby the light-induced magnetization changes in the KNiCr-PBA shell are due to realignment of the local magnetic anisotropy as a result of the structural changes in the shell associated with the optical CTIST of the core. Through magnetization and structural analyses, the depth to which the properties of the shell are influenced by the core-shell architecture was estimated to be between 40 and 50 nm.

A rare four-step spin crossover transition has been attained in a two-dimensional Hofmann-type material through the presence of an array of antagonistic host–host and host–guest interactions.

A new functionalized 1,2,4-triazole ligand, 4-[(E)-2-(5-methyl-2-thienyl)vinyl]-1,2,4-triazole (thiome), was prepared to assess the broad applicability of strategically producing multistep spin transitions in two-dimensional Hofmann-type materials of the type [FeIIPd(CN)4(R-1,2,4-trz)2]·nH2O (R-1,2,4-trz = a 4-functionalized 1,2,4-triazole ligand). A variety of structural and magnetic investigations on the resultant framework material [FeIIPd(CN)4(thiome)2]·2H2O (A·2H2O) reveal that a high-spin (HS) to low-spin (LS) transition is inhibited in A·2H2O due to a combination of guest and ligand steric bulk effects. The water molecules can be reversibly removed with retention of the porous host framework and result in the emergence of an abrupt and hysteretic one-step spin transition due to the removal of guest internal pressure. A spin transition can, furthermore, be induced in A·2H2O (0-0.68 GPa) under hydrostatic pressure, as evidenced by variable-pressure structure and magnetic studies, resulting in a two-step spin transition at ambient temperatures at 0.68 GPa. The presence of a two-step spin crossover (SCO) in A·2H2O under hydrostatic pressure compared to a one-step SCO in A at ambient pressure is discussed in terms of the relative ability of each phase to accommodate mixed HS/LS states according to differing lattice flexibilities.

In situ synchrotron powder diffraction has been used to probe the pressure-dependent structural properties of the magnetic molecular framework material Co(dca)2 [dca = dicyanamide or N(CN)2(-)]. An orthorhombic (Pmnn) to monoclinic (P2₁/n) transformation to a high-pressure phase, namely γ-Co(dca)2, occurs at 1.1 GPa. Structural determination of γ-Co(dca)2 shows that the rutile-like topology of the pristine material is retained at high pressures, with the lower symmetry allowing a progression of volume-reducing structural distortions. γ-Co(dca)2 was stable at the maximum pressure measured of 4.2 GPa. Both phases were soft, with bulk moduli (B0) for α-Co(dca)2 and γ-Co(dca)2 of 13.15 (18) and 9.0 (6) GPa, respectively. Modest uniaxial negative linear compressibility (K) of the order of -4 TPa(-1) was observed over the entire measured pressure range.

Correction for 'Hydrophobic pillared square grids for selective removal of CO2 from simulated flue gas' by Sameh K. Elsaidi et al., Chem. Commun., 2015, 51, 15530-15533.

The pressure-induced structural phase transition in the intermediate-valence compound CeNi has been investigated by x-ray and neutron powder diffraction techniques. It is shown that the structure of the pressure-induced CeNi phase (phases) can be described in terms of the Pnma space group. Equations of state for CeNi on both sides of the phase transition are derived and an approximate P-T phase diagram is suggested for P<8 GPa and T<300 K. The observed Cmcm→Pnma structural transition is then analyzed using density functional theory calculations, which successfully reproduce the ground state volume, the phase transition pressure, and the volume collapse associated with the phase transition.

CaZrF 6 (I), CaHfF 6 (II), and CoZrF 6 (III) are prepared by solid state reaction of CaF 2 (CoF 2 ) and ZrF 4 (HfF 4 ) in equimolar amounts (Cu or Ni tube in evacuated quartz tubes, 750 °C (I) or 850 °C (II, III), 24 h).

Enhancement of adsorption capacity and separation of radioactive Xe/Kr at room temperature and above is a challenging problem. Here, we report a detailed structural refinement and analysis of the synchrotron X-ray powder diffraction data of Ni-DODBC metal organic framework with in situ Xe and Kr adsorption at room temperature and above. Our results reveal that Xe and Kr adsorb at the open metal sites, with adsorption geometries well reproduced by DFT calculations. The measured temperature-dependent adsorption capacity of Xe is substantially larger than that for Kr, indicating the selectivity of Xe over Kr and is consistent with the more negative adsorption energy (dominated by van der Waals dispersion interactions) predicted from DFT. Our results reveal critical structural and energetic information about host-guest interactions that dictate the selective adsorption mechanism of these two inert gases, providing guidance for the design and synthesis of new MOF materials for the separation of environmentally hazardous gases from nuclear reprocessing applications.

Capture of CO2 from flue gas is considered to be a feasible approach to mitigate the effects of anthropogenic emission of CO2. Herein we report that an isostructural family of metal organic materials (MOMs) of general formula [M(linker)(2)(pillar)], linker = pyrazine, pillar = hexaflourosilicate and M = Zn, Cu, Ni and Co exhibits highly selective removal of CO2 fromdry and wet simulated flue gas. Two members of the family, M = Ni and Co, SIFSIX-3-Ni and SIFSIX-3-Co, respectively, are reported for the first time and compared with the previously reported Zn and Cu analogs.

The electrochemical performance and mechanism of a MIL-101(Fe) metal–organic framework (MOF) as a lithium ion battery electrode is reported for the first time.

Rapid shifts in the energy, technological, and environmental demands of materials science call for focused and efficient expansion of the library of functional inorganic compounds. To achieve the requisite efficiency, we need a materials discovery and optimization paradigm that can rapidly reveal all possible compounds for a given reaction and composition space. Here we provide such a paradigm via in situ X-ray diffraction measurements spanning solid, liquid flux, and recrystallization processes. We identify four new ternary sulfides from reactive salt fluxes in a matter of hours, simultaneously revealing routes for ex situ synthesis and crystal growth. Changing the flux chemistry, here accomplished by increasing sulfur content, permits comparison of the allowable crystalline building blocks in each reaction space. The speed and structural information inherent to this method of in situ synthesis provide an experimental complement to computational efforts to predict new compounds and uncover routes to targeted materials by design.

Synchrotrons have revolutionized powder diffraction. They enable rapid collection of data with tremendous angular resolution and exceptional statistics. High resolution powder diffraction beamlines employing multiple single crystal analyzer detectors routinely reveal subtle crystallographic distortions undetectable on other powder instruments, and are an important tool at most modern synchrotrons for structural studies of a diverse range of materials. Beamline 11-BM at the Advanced Photon Source (APS) is a dedicated high resolution (ΔQ/Q ~2×10-4) powder diffraction instrument which uses vertical and horizontal beam focusing capabilities and a counting system consisting of twelve perfect crystal analyzers paired with scintillator detectors. This APS beamline supports both traditional on-site experiments and a highly successfully rapid access mail-in program mode. This mail-in program has greatly simplified access for a growing user community (> 250 in 2013) to world-class synchrotron quality powder data for their research and resulting publications (> 100 11-BM citations in 2013). The presentation will provide an overview of 11-BM's unique mail-in program. It will be presented both from the view of an external remote user, and will also highlight the numerous alignment, calibration, correction and merging software routines needed to efficiently and accurately reduce the numerous multi-bank detector datasets associated with a high throughput user program. An integrated web interface has been developed to serve as a user-friendly relational database interface for tracking of samples and datasets throughout all stages of the measurements; from the initial user request to sample disposal. The database and software tools critical for this high-throughput synchrotron powder diffraction program will be discussed in detail. More information about the 11-BM and its mail-in program can be found on the beamline webpage: http://11bm.xray.aps.anl.gov