47 research outputs found
Versatile spectroscopic cell for operando studies in heterogeneous catalysis using tender Xâray spectroscopy in fluorescence mode
Mirror Furnace for Synchrotron Dark Field X-ray Microscopy Experiments
We present a multi-purpose mirror furnace designed for synchrotron X-ray
experiments. The furnace is optimized specifically for dark-field X-ray
microscopy (DFXM) of crystalline materials at the beamline ID06 of the ESRF.
The furnace can reach up to ~1600{\deg}C with stability better than 2{\deg}C,
and heating and cooling rates up to 30{\deg}C/s. The contact-less design
enables samples to be heated either in air or in a controlled atmosphere in a
capillary tube. The temperature was calibrated via the thermal expansion of an
a-iron grain. Temperature profiles in the y and z axes were measured by
scanning a thermocouple through the focal spot of the furnace. In the current
configuration of the beamline, the furnace can be used for DFXM, near-field
X-ray topography, bright field X-ray nanotomography, high resolution reciprocal
space mapping, and limited powder diffraction experiments. As a first
application, we present a DFXM case study on isothermal heating of a
commercially pure Al single crystal
Simultaneous resonant x-ray diffraction measurement of polarization inversion and lattice strain in polycrystalline ferroelectrics
International audienceStructure-property relationships in ferroelectrics extend over several length scales from the individual unit cell to the macroscopic device, and with dynamics spanning a broad temporal domain. Characterizing the multi-scale structural origin of electric field-induced polarization reversal and strain in ferroelectrics is an ongoing challenge that so far has obscured its fundamental behaviour. By utilizing small intensity differences between Friedel pairs due to resonant scattering, we demonstrate a time-resolved X-ray diffraction technique for directly and simultaneously measuring both lattice strain and, for the first time, polarization reversal during in-situ electrical perturbation. This technique is demonstrated for BaTiO3-BiZn0.5Ti0.5O3 (BT-BZT) polycrystalline ferroelectrics, a prototypical lead-free piezoelectric with an ambiguous switching mechanism. This combines the benefits of spectroscopic and diffraction-based measurements into a single and robust technique with time resolution down to the ns scale, opening a new door to in-situ structure-property characterization that probes the full extent of the ferroelectric behaviou
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Simultaneous resonant x-ray diffraction measurement of polarization inversion and lattice strain in polycrystalline ferroelectrics
Structure-property relationships in ferroelectrics extend over several length scales from the individual unit cell to the macroscopic device, and with dynamics spanning a broad temporal domain. Characterizing the multi-scale structural origin of electric field-induced polarization reversal and strain in ferroelectrics is an ongoing challenge that so far has obscured its fundamental behaviour. By utilizing small intensity differences between Friedel pairs due to resonant scattering, we demonstrate a time-resolved X-ray diffraction technique for directly and simultaneously measuring both lattice strain and, for the first time, polarization reversal during in-situ electrical perturbation. This technique is demonstrated for BaTiOâ-BiZnâ.â
Tiâ.â
Oâ (BT-BZT) polycrystalline ferroelectrics, a prototypical lead-free piezoelectric with an ambiguous switching mechanism. This combines the benefits of spectroscopic and diffraction-based measurements into a single and robust technique with time resolution down to the ns scale, opening a new door to in-situ structure-property characterization that probes the full extent of the ferroelectric behaviour.This is the publisherâs final pdf. The published article is copyrighted by the author(s) and published by the Nature Publishing Group. The published article can be found at: http://www.nature.com/srep
Testing for an effect of a mindfulness induction on child executive functions
Several sessions of mindfulness practice can exert positive gains for child executive functions (EF); however, the evidence for effects of a mindfulness induction, on EF for adults, is mixed and this effect has not been tested in children. The immediate effect of an age appropriate 3-min mindfulness induction on EF of children aged 4â7 years was tested. Participants (N =â156) were randomly assigned to a mindfulness induction or dot-to-dot activity comparison group before completing four measures of EF. A composite score for EF was calculated from summed z scores of the four EF measures. A difference at baseline in behavioural difficulties between the mindfulness induction and comparison group meant that data was analysed using a hierarchical regression. The mindfulness induction resulted in higher average performance for the composite EF score (Mâ= 0.12) compared to the comparison group (M =âââ0.05). Behavioural difficulties significantly predicted 5.3% of the variance in EF performance but participation in the mindfulness or comparison induction did not significantly affect EF. The non-significant effect of a mindfulness induction to exert immediate effects on EF fits within broader evidence reporting mixed effects when similar experimental designs have been used with adults. The findings are discussed with consideration of the extent to which methodological differences may account for these mixed effects and how mindfulness inductions fit within broader theoretical and empirical understanding of the effects of mindfulness on EF
Synthesis and Characterization of Cs<sub>1-x</sub>Ti<sub>2</sub>Te<sub>2</sub>O (x â 0.2): Electron Doping by Te Resulting in a Layered Metal
Reacting Cs2O1.3, TiTe, TiO2, and Te under inert conditions gives powders of Cs1-xTi2Te2O (x approximate to 0.2). Small single crystals of the same phase were obtained from a CsCl salt melt in closed ampoules. This cesium dititanium ditelluride oxide (P4/mmm, a = 4.0934(3) angstrom, c = 8.9504(9) angstrom) is isostructural to CeCr2Si2C and contains layers of face-sharing trans-TiTe4O2 octahedra that are separated by Cs. As Ti occupies only one crystallographic site, its average oxidation state is +2.6, for the Cs deficit x = 0.2. The formally intermediate Ti valence state agrees well with the metallic conductivity and temperature-independent paramagnetic behavior. No superconductivity is observed down to 0.1 K in Cs0.8Ti2Te2O, but the fact that this structure type can accommodate Te2- suggests that electron doping of structurally closely related pnictide oxide superconductors, for example, BaTi2Bi2O, might be possible
Impact of thermal variations on biochemical and physiological traits
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