Deciphering role of the Fe substitution in modulating the structural, magnetic and magnetocaloric properties of NdCrTi5\mathrm{NdCrTi_{5}}

A detailed magnetic study on the Fe substituted $\mathrm{NdCrTi_{5}}$is presented. Phase purity of polycrystalline $\mathrm{NdCr_{0.5}Fe_{0.5}TiO_5}$ prepared by conventional solid-state technique has been confirmed by synchrotron X-ray diffraction (SXRD). Temperature-dependent magnetization (MT) measurements indicate a transition to an antiferromagnetic (AFM) type of magnetic ordering at $T_N  ∼$ 10 K. AFM type of order is also supported by magnetocaloric data. Magnetic hysteresis as well as a type of magnetic relaxation behavior collected below (at 5 K) indicate the presence of weak ferromagnetism

High-Pressure High-Temperature Stability and Thermal Equation of State of Zircon-Type Erbium Vanadate

The zircon to scheelite phase boundary of ErVO$_4$ has been studied by high-pressure and high-temperature powder and single-crystal X-ray diffraction. This study has allowed us to delimit the best synthesis conditions of its scheelite-type phase, determine the ambient-temperature equation of state of the zircon and scheelite-type structures, and obtain the thermal equation of state of the zircon-type polymorph. The results obtained with powder samples indicate that zircon-type ErVO$_4$ transforms to scheelite at 8.2 GPa and 293 K and at 7.5 GPa and 693 K. The analyses yield bulk moduli K$_0$ of 158(13) GPa for the zircon phase and 158(17) GPa for the scheelite phase, with a temperature derivative of dK$_0$/dT = −[3.8(2)] × 10$^{–3}$ GPa K$^{–1}$ and a volumetric thermal expansion of $α_0$ = [0.9(2)] × 10$^{–5}$ K$^{–1}$ for the zircon phase according to the Berman model. The results are compared with those of other zircon-type vanadates, raising the need for careful experiments with highly crystalline scheelite to obtain reliable bulk moduli of this phase. Finally, we have performed single-crystal diffraction experiments from 110 to 395 K, and the obtained volumetric thermal expansion $(α_0 )$ for zircon-type ErVO$_4$ in the 300–395 K range is [1.4(2)] × 10$^{–5}$ K$^{–1}$, in good agreement with previous data and with our experimental value given from the thermal equation of state fit within the limits of uncertainty

On site-selective optically and thermally induced processes in Lu2O3:Tb,Ta\mathrm{{Lu_2O_3}:Tb,Ta} storage phosphors

Photo- thermo- and optically stimulated luminescence properties of $\mathrm{Lu_2O_3:Tb,Ta}$ ceramics sintered at 1700 °C in air were investigated. Low temperature (10 K) excitation and emission spectra using synchrotron excitation in the range of 150–330 nm are also discussed. The effect of the dopant contents on the various luminescence effects and processes was tackled. The ceramics showed intense thermoluminescence (TL) and the glow curve consisted of two main peaks around 170 and 250 °C upon 5 °C/s heating rate. The shape of the glow curve and TL intensity depended strongly on the dopant concentrations. Above 0.1% of their contents the TL quickly lessened to disappear around 1%. This was in contrary to photoluminescence which hardly showed any quenching up to the concentration of 1%. In addition to the regular first order TL kinetics some contribution from tunneling and semi-localized transitions was proved

Software Platform for European XFEL: Towards Online Experimental Data Analysis

Large amount of data being generated at large scale facilities like European X-ray Free-Electron Laser (XFEL) requires new approaches for data processing and analysis. One of the mostcomputationally challenging experiments at an XFEL is single-particle structure determination.In this paper we propose a new design for an integrated software platform which combines well establishedtechniques for XFEL data analysis with High Performance Data Analysis (HPDA)methods. In our software platform we use streaming data analysis algorithms with high performancecomputing solutions. This approach should allow analysis of the experimental dataflow in quasionlineregime

Experimental Observation of Crystal–Liquid Coexistence in Slit-Confined Nonpolar Fluids

Films of carbon tetrachloride (CCl$_4$) confined in slit geometry between two flat diamond substrates down to a few tens of Angstroms are studied by combining X-ray reflectivity with in-plane and out-of-plane X-ray scattering. The confined films form a heterogeneous structure with coexisting regions of liquid and crystalline phases. The liquid phase shows short-range ordering normal to the surfaces of the substrates. The experiments directly show the ability of the confinement to induce crystal objects, which is a long-discussed issue in the literature. The surface structure and morphology of the substrates may influence the actual realization of the crystalline phase in confinement

Structure Determination by Continuous Diffraction from Imperfect Crystals

The coherent diffraction pattern of a non-periodic finite object does not consist of Bragg peaks but is continuously and smoothly varying. Such patterns do not suffer from the well-known phase problem of crystallography. In this case, robust iterative algorithms exist to determine the electron density of the object from the diffraction pattern alone. Continuous diffraction is accessible from ensembles of aligned molecules, including disordered protein crystals. We discuss the application of the concepts of coherent diffractive imaging to such cases and describe the experimental considerations to adequately measure the weak continuous diffraction signals

Annealing-assisted high-pressure torsion in Zr55Cu30Al10Ni5\mathrm{Zr_{55}Cu_{30}Al_{10}Ni_{5}} metallic glass

For bulk metallic glasses (BMGs) structural anisotropy has been studied for many years, but usually for small creep strains, rather than for large strains associated with the viscoplastic flow. In this study, the structural modifications in the short-to-medium range order of $\mathrm{Zr_{55}Cu_{30}Al_{10}Ni_{5}}$ BMG is deliberated for the first time upon simultaneous high-pressure torsion (HPT) and in-situ annealing around the glass transition temperature $(T_{g})$. The changes are evaluated in terms of hardness by microindentation, thermal properties by differential thermal calorimetry, chemistry by energy dispersive X-ray, and structural properties by synchrotron X-ray diffraction and transmission electron microscopy. A remarkable increase of the glass transition temperature and the absence of the shoulder of the crystallization peak along with remarkable softening and shear thinning reveals that even at $T_g$ the material gains flow characteristics because of the extreme pressure applied. A clear shift towards smaller wave vector $Q$ in the peak positions of the partial distribution function $G(r)$ , and reconfiguration of the bonding between $Zr - Zr$ and $Zr - Cu$ atomic pairs extracted from the deconvolution of the radial distribution function $RDF(r)$ are observed with changing the processing temperature. The findings give insight into the atomic and nano-scale modifications in BMGs due to high-pressure torsion at different temperatures which would be essential to tune the intrinsic properties of BMGs to attain the desirable hardness and thermal stability for a specific application

An adaptive scheme for suppression of higher harmonics in an undulator

An undulator usually emits radiation at the energy of the fundamental wavelength and the higher harmonics at the same time. Likewise, monochromators with gratings or low-indexed crystals also transmit these higher harmonics with substantial efficiency. Most experiments, however, require a clean monochromatic spectrum and use mirrors or a detuning of the monochromator to suppress the higher harmonics in the spectrum. A quasi-periodic undulator is a well- established device which shifts the position of the higher harmonics to non-integer multiples of the fundamental and helps to improve the signal-to-background ratio in the measurement significantly.We have implemented a new alternative concept for suppression of higher harmonics which can be adapted on the fly during operation of the undulator. It is based on creating a distinct phase step in the center of the magnet structure which leads to a tailored distortion of the emitted spectrum. For that purpose, a permanent magnet phase shifter is embedded into the magnet structure of a planar hybrid undulator. We discuss the principle and technical implementation of this scheme, and present first experimental results

Design status of the ultra-low emittance synchrotron facility PETRA IV

At DESY the Synchrotron Light Source PETRA III offers scientists outstanding opportunities for experiments with hard X-rays of exceptionally high brilliance since 2009. Research activities have been started to upgrade PETRA III to the ultra-low emittance source PETRA IV, which will be diffraction limited up to the hard X-ray range. Therefore the future light source PETRA IV will be ideal for 3D X-ray microscopy of biological, chemical, and physical processes under realistic conditions at length scales from atomic dimensions to millimeters. The lattice design is aiming for a horizontal emittance in the range between 10 pm rad and 30 pm rad at a beam energy of 6 GeV. Presently, two different approaches are considered for the lattice design: a design based on a hybrid multibend achromat with an interleaved sextupole configuration based on the ESRF-EBS design, and a lattice with a double non-interleaved sextupole configuration. The current status of the design activities is reported including the injector and several technical aspects

FAST-XPD: XFEL Photon Pulses Database for Modeling XFEL Experiments

Knowledge of different properties of the radiation from X-ray FEL is very important for planning experiments. An understanding of such properties can come from start-to-end simulations of experiments: modern FEL simulation allows to reliably predict the output radiation pulses from X-ray FEL. We present a web a ccessible XFEL photon pulses simulation database showing data calculated with the FAST simulation framework