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Journal of synchrotron radiation 30(4), 671 - 685 (2023). doi:10.1107/S1600577523003910, An experimental platform for dynamic diamond anvil cell (dDAC) research hasbeen developed at the High Energy Density (HED) Instrument at the EuropeanX-ray Free Electron Laser (European XFEL). Advantage was taken of the highrepetition rate of the European XFEL (up to 4.5 MHz) to collect pulse-resolvedMHz X-ray diffraction data from samples as they are dynamically compressed atintermediate strain rates ( 10 3 s1), where up to 352 diffraction images can becollected from a single pulse train. The set-up employs piezo-driven dDACscapable of compressing samples in 340 ms, compatible with the maximumlength of the pulse train (550 ms). Results from rapid compression experimentson a wide range of sample systems with different X-ray scattering powers arepresented. A maximum compression rate of 87 TPa s1 was observed duringthe fast compression of Au, while a strain rate of 1100 s1 was achievedduring the rapid compression of N2 at 23 TPa s1., Published by Wiley-Blackwell, [Erscheinungsort nicht ermittelbar]

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Materials with an intrinsic (ultra)low lattice thermal conductivity (k$_L$) are critically important for the development of efficient energy conversion devices. In the present work, we have investigated microscopic origins of low k$_L$ behavior in BaO, BaS and MgTe by exploring lattice dynamics and phonon transport of 16 iso-structural MX (Mg, Ca, Sr, Ba and X = O, S, Se and Te) compounds in the rocksalt (NaCl)-type structure by comparing their lattice transport properties with the champion thermoeletric iso-structural material, PbTe. Anomalous trends are observed for k$_L$ in MX compounds except the MgX series in contrast to the expected trend from their atomic mass. The underlying mechanisms for such low k$_L$ behavior in relatively low atomic mass systems namely BaO, BaS and MgTe compounds are thoroughly analyzed. We propose the following dominant factors that might be responsible for low k$_L$ behavior in these materials: 1) softening of transverse acoustic (TA) phonon modes despite low atomic mass, 2) low lying optic (LLO) phonon modes fall deep into acoustic mode region which enhances overlap between longitudinal acoustic (LA) and LLO phonon modes which increases scattering phase space, 3) short phonon lifetimes and high scattering rates, 4) relatively high density (\r{ho}) and large Gr\"uneisen parameter. Moreover, tensile strain also causes a further reduction in k$_L$ for BaO, BaS and MgTe through phonon softening and near ferroelectric instability. Our comprehensive study on 16 binary MX compounds might provide a pathway for designing (ultra)low k$_L$ materials even with simple crystal systems through phonon engineering., Comment: 40 pages, 10 figures

We present the results of a combined study of shocked labradorite from the Lonar crater, India, using optical microscopy, micro-Raman spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, high-energy X-ray total scattering experiments, and micro-Fourier transform infrared (micro-FTIR) spectroscopy. We show that maskelynite of shock class 2 is structurally more similar to fused glass than to crystalline plagioclase. However, there are slight but significant differencespreservation of original preimpact igneous zoning, anisotropy at infrared wavelengths, X-ray anisotropy, and preservation of some intermediate range orderwhich are all consistent with a solid-state transformation from plagioclase to maskelynite.