High-resolution Powder Diffractometer Research Articles

High-Resolution Powder Diffractometer Facility (HRPDF) for Low and Medium Power Research Reactor

Abstract: The present paper suggests a design of a high-resolution powder diffractometer facility that fits the low and medium power research reactors. The design choice guarantees the acceptable cost of a high-standard facility. Some components can be created in-house, while the design also includes detailed information about the commercially available components. It is highly recommended to carry out Monte Carlo simulations of realistic expected luminosity and resolution parameters of the finally designed and approved instrument in advance. Monte Carlo simulations can eventually show which components should be modified in order to achieve the expected resolution and luminosity parameters of the facility. Keywords: High-resolution powder diffractometer, Design, Construction, Low and medium research reactors.

Upgrade of Xuanwu: A dual-mode neutron powder diffractometer at CMRR

Neutron diffraction (ND) is a well-established technique of great significance in condensed physics and materials science. Although it has particular advantages against its brother X-ray diffraction (XRD), intensity is still a limiting factor counteracting its application. Herein, we report the upgrade of Xuanwu, a high-resolution neutron powder diffractometer at the China Mianyang Research Reactor (CMRR). A doubly focusing monochromator system made of Si blades is applied to enhance the intensity from 2 × 105n⋅cm−2⋅s−1 to 2.39 × 106n⋅cm−2⋅s−1 with changeable wavelength. The high-resolution mode with a best resolution 1.6‰ is reserved, which means the working style is optional between high-resolution and high-intensity, making Xuanwu more applicable in expanded scopes.

Visualizing lithium ions in the crystal structure of Li3PO4 by in situ neutron diffraction

Li3PO4 is known to demonstrate Li+ ionic conductivity, making it a good candidate for solid electrolytes in all-solid batteries. Understanding the crystal structure and its connection to Li+ diffusion is essential for further rational doping to improve the ionic transport mechanism. The purpose of this study is to investigate this mechanism using anisotropic displacement parameters (ADPs), nuclear density distribution and bond valence mapping. In situ neutron powder diffraction experiments have been performed using the high-resolution powder diffractometer ECHIDNA at the OPAL reactor, Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, NSW, Australia. The ADPs and nuclear density distribution were determined from the analysis of neutron diffraction data using the Rietveld method, whereas the bond valence map was calculated from the refined structure. The crystal structure remained unchanged as the temperature was increased (3, 100, 300 and 400 K). However, the ADPs show a greater increase in anisotropy in the a and b axes compared with the c axis, indicating the tendency of the ionic movement. By combining nuclear density distribution and bond valence mapping, the most likely lithium-ion diffusion in the crystal structure can be visualized.

世界最高分解能TOF型粉末中性子回折装置SuperHRPDの開発

世界最高分解能TOF型粉末中性子回折装置SuperHRPDの開発

高分解能粉末中性子回折装置HRPDの紹介

高分解能粉末中性子回折装置HRPDの紹介

DEVELOPMENT OF AUTOMATIC DATA PROCESSING FOR BATAN’S HRPD AND FCD/TD USING PYTHON CODE

High Resolution Powder Diffractometer (HRPD) and Four Circle Diffractometer/Texture Diffractometer (FCD/TD) are two BATAN-owned neutron diffractometers which have been fully operational since 1992. These are used to investigate structure and texture of crystalline materials, respectively. Before analyzing, the acquired raw neutron diffraction data should first be processed in a specific way to achieve the suitable data format required by the analysis software. This data processing step is a repetitive task for every single experiment which is previously done manually and very time-consuming. The purpose of this development project was to optimize this step to be fully automatic and executable by a code. This work was performed by means of Python code utilizing the array manipulation in re-arranging and re-formatting the raw data. The resulted Python codes were named as hrpd.py and fcdtd.py. These have been successfully done and validated, making data processing step easier, simpler, and significantly faster with only 20 seconds or less required.Keywords: HRPD, FCD/TD, Automatic Data Processing, Neutron Diffraction, Python

The Certification of Standard Reference Material 1979: Powder Diffraction Line Profile Standard for Crystallite Size Analysis.

This rather long-standing project has resulted in a National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) for the analysis of crystallite size from a consideration of powder diffraction line profile broadening. It consists of two zinc oxide powders, one with a crystallite size distribution centered at approximately 15 nm, and a second centered at about 60 nm. These materials display the effects of stacking faults that broaden specific hkl reflections and a slight amount of microstrain broadening. Certification data were collected on the high-resolution powder diffractometer located at beamline 11-BM of the Advanced Photon Source, and on a NIST-built laboratory diffractometer equipped with a Johansson incident beam monochromator and position sensitive detector. Fourier transforms were extracted from the raw data using a modified, two-step profile fitting procedure that addressed the issue of accurate background determination. The mean column lengths, 〈L〉area and 〈L〉vol, were then computed from the Fourier transforms of the specimen contribution for each reflection. Data were also analyzed with fundamental parameters approach refinements using broadening models to yield 〈L〉area and 〈L〉vol values. These values were consistent with the model-independent Fourier transform results; however, small discrepancies were noted for the 〈L〉area values from both machines and both crystallite size ranges. The fundamental parameters approach fits to the laboratory data yielded the certified lattice parameters.

HRPD-X; a proposed upgrade to the ISIS High-Resolution Powder Diffractometer

HRPD-X is a proposal to completely replace the current high-resolution powder diffractometer (HRPD) at the ISIS Neutron and Muon Source. The new instrument is expected to deliver a factor of four increase in solid-angle coverage. Taking advantage of new detector technology and coupled with a non-magnetic sample tank and improved incident- and diffracted-beam collimation, the new instrument will substantially improve HRPD’s scientific capabilities to study magnetic structures and behaviour, high-pressure phenomena and supramolecular structures whilst strengthening its performance in already-established areas.

Thermal expansion of the Al2SiO5 polymorphs, kyanite, andalusite and sillimanite, between 10 and 1573 K determined using time-of-flight neutron powder diffraction

Powder and single-crystal diffraction data measured from the three geologically important Al2SiO5 polymorphs, kyanite, andalusite and sillimanite, over the last six decades have given varying accounts of each polymorph’s thermal expansion, the scatter between and even within experimental datasets often being quite large. Furthermore, there are no lattice parameter determinations below 273 K, where the thermodynamic functions vary substantially, and few measurements above 1200 K. Accurate and precise lattice parameters of natural kyanite, andalusite and sillimanite have therefore been obtained in the range 10–1573 K using the high-resolution powder diffractometer (HRPD) at the ISIS neutron spallation source. Accuracy is ensured by the use of an internal standard (NIST silicon SRM640c) and use of a bulk probe (neutrons) to avoid the specimen-displacement corrections required by typical back-reflection X-ray diffraction methods. Precision is ensured by use of the time-of-flight method on one of the longest primary neutron flightpath instruments in the world. For kyanite, the improved precision reveals the true temperature dependence of the three inter-axial angles for the first time, permitting derivation of accurate thermal expansion tensor coefficients. For both andalusite and sillimanite, the measurements reveal hitherto unknown regions of substantial negative linear expansivity below room temperature, along the c-axis in andalusite and along the a-axis in sillimanite. Above 1200 K, sillimanite exhibits an anomalous increase in thermal expansion that may be due to a change in the Al/Si tetrahedral site ordering.

Diffraction Line Profile Analysis of 3D Wedge Samples of Ti-6Al-4V Fabricated Using Four Different Additive Manufacturing Processes

Wedge-shaped samples were manufactured by four different Additive Manufacturing (AM) processes, namely selective laser melting (SLM), electron beam melting (EBM), direct metal deposition (DMD), and wire and arc additive manufacturing (WAAM), using Ti-6Al-4V as the feed material. A high-resolution powder diffractometer was used to measure the diffraction patterns of the samples whilst rotated about two axes to collect detected neutrons from all possible lattice planes. The diffraction pattern of a LaB6 standard powder sample was also measured to characterize the instrumental broadening and peak shapes necessary for the Diffraction Line Profile Analysis. The line profile analysis was conducted using the extended Convolution Multiple Whole Profile (eCMWP) procedure. Once analyzed, it was found that there was significant variation in the dislocation densities between the SLMed and the EBMed samples, although having a similar manufacturing technique. While the samples fabricated via WAAM and the DMD processes showed almost similar dislocation densities, they were, however, different in comparison to the other two AM processes, as expected. The hexagonal (HCP) crystal structure of the predominant α-Ti phase allowed a breakdown of the percentage of the Burgers’ vectors possible for this crystal structure. All four techniques exhibited different combinations of the three possible Burgers’ vectors, and these differences were attributed to the variation in the cooling rates experienced by the parts fabricated using these AM processes.

ECHIDNA: a decade of high-resolution neutron powder diffraction at OPAL

The ECHIDNA high-resolution neutron powder diffractometer at the 20 MW OPAL research reactor in Australia produces high-quality data for a broad spectrum of crystal and magnetic structural studies. The paper presents an overview of the current status of the hardware, latest developments in data-reduction software, statistics on instrument usage and the user programme, and instrument limitations.

High-resolution Guinier powder diffractometer combined with multilayer optics

High-resolution Guinier powder diffractometer combined with multilayer optics

X-ray diffractometer for the investigation of temperature- and magnetic field-induced structural phase transitions

This article reports the development and characterization of a laboratory-based high-resolution X-ray powder diffractometer equipped with a 5.5 T magnet and closed-cycle helium cryostat that is primarily designed for the investigation of magneto-structural phase transitions. Unique features of the diffractometer include the position-sensitive detector, allowing the collection of an entire diffraction pattern at once, and the high energy resolution with Mo Kα1radiation. The ability to utilize a lower energy resolution but higher photon flux by switching to an X-ray mirror monochromator makes it a versatile setup for a variety of compounds. In this contribution, details of the design and performance of the instrument are presented along with its specifications.

Energy research with neutrons (ErwiN) and installation of a fast neutron powder diffraction option at the MLZ, Germany.

The need for rapid data collection and studies of small sample volumes in the range of cubic millimetres are the main driving forces for the concept of a new high-throughput monochromatic diffraction instrument at the Heinz Maier-Leibnitz Zentrum (MLZ), Germany. A large region of reciprocal space will be accessed by a detector with sufficient dynamic range and microsecond time resolution, while allowing for a variety of complementary sample environments. The medium-resolution neutron powder diffraction option for 'energy research with neutrons' (ErwiN) at the high-flux FRM II neutron source at the MLZ is foreseen to meet future demand. ErwiN will address studies of energy-related systems and materials with respect to their structure and uniformity by means of bulk and spatially resolved neutron powder diffraction. A set of experimental options will be implemented, enabling time-resolved studies, rapid parametric measurements as a function of external parameters and studies of small samples using an adapted radial collimator. The proposed powder diffraction option ErwiN will bridge the gap in functionality between the high-resolution powder diffractometer SPODI and the time-of-flight diffractometers POWTEX and SAPHiR at the MLZ.

Accurate and precise lattice parameters of H2O and D2O ice Ih between 1.6 and 270 K from high-resolution time-of-flight neutron powder diffraction data.

Accurate and precise lattice parameters for D2O and H2O varieties of hexagonal ice (ice Ih, space group P63/mmc) have been obtained in the range 1.6 to 270 K. Precision of the lattice parameters (∼0.0002% in a and 0.0004% in c for D2O, 0.0008% in a and 0.0015% in c for H2O) is ensured by use of the time-of-flight method on one of the longest primary neutron flight-path instruments in the world, the High-Resolution Powder Diffractometer at the ISIS neutron source. These data provide a more precise description of the negative thermal expansion of the material at low temperatures than the previous synchrotron `gold standard' [Röttger et al. (1994). Acta Cryst. B50, 644-648], including the region below 10 K where the lattice parameters saturate. The volume expansivity of both isotopologues turns negative below 59-60 K, in excellent agreement with a recent dilatometry study. The axial expansivities are highly isotropic (differing by < 1% in D2O ice Ih). Furthermore, the c/a ratio of different D2O ice samples exhibit a statistically significant dispersion of ∼0.015% below 150 K that appears to depend on the thermal history of the sample, which disappears on warming above 150 K. Similarly, H2O ice exhibits a `kink' in the c/a ratio at ∼115 K. The most plausible explanation is a freezing-in of the molecular reorientation process on cooling and subsequent relaxation on warming.

Conceptual design of a new high-resolution powder diffractometer at Jordan Research and Training Reactor

The Jordan Research and Training Reactor (JRTR) has started its full power operation of 5 MW, upgradable to 10 MW, since December 7, 2016. Currently, the JRTR is planning to install a new high-resolution powder diffractometer (HRPD) at the ST1 beam tube in the near future. This study aims to design an optimum HRPD based on the specifications and characteristics of the JRTR. This investigation is based on the manipulation of the components of HRPD such as monochromator crystals, collimators, detectors, and samples by using McStas software. This study shows that the Jordanian HRPD can achieve a neutron flux up to ∼106 n/cm2·s at a sample position with a good resolution of Δd/d = 2.0 × 10−3. The detection system can cover a large range of scattering angles [5°, 165°] by using an array of 64 He-3 position-sensitive detectors provided with 10 arc min of a Soller collimator in front of each detector.

H/D isotope effect on the molar volume and thermal expansion of benzene.

Time-of-flight neutron powder diffraction data have been collected from C6H6 and C6D6, as a function of temperature between 10 and 276 K using the High Resolution Powder Diffractometer at the ISIS Neutron and Muon Source. In order to achieve high accuracy and precision both in the determination of lattice parameters and in the control of the sample temperature, data were acquired using the same instrumental conditions for each isotopologue with an internal NIST silicon standard and in situ-heated sample holders. In contrast with the work from J. D. Dunitz and R. M. Ibberson, Angew. Chem. Int. Ed., 2008, 47, 4208-4210, we find that the difference in molar volume between the two isotopologues is almost invariant with temperature and that the anisotropic linear expansivities of the crystallographic axes are nearly identical in C6H6 and C6D6.

Magnetoelastic coupling forbidden by time-reversal symmetry: Spin-direction-dependent magnetoelastic coupling on MnO, CoO, and NiO

In the Landau free energy, which is a powerful tool for describing the physical properties and phase transitions in condensed-matter physics, it has been generally believed that time-reversal symmetry allows only even-power polynomials in the magnetic moment when magnetic transition happens. Although no experimental evidence supports it, this symmetry constraint is very strict in theory. On the other hand, MnO, CoO, and NiO have been extensively studied for several decades since these materials are used to test advance experimental and theoretical methods. However, their precise spin directions and phase-transition mechanism have remained as a long-standing problem until now. To resolve these issues, we used the cutting-edge time-of-flight neutron powder diffractometer (SuperHRPD) at the Japan Proton Accelerator Research Complex (J-PARC) to study the spin-direction-dependent magnetoelastic coupling in MnO, CoO, and NiO. We also constructed a group-subgroup structure relation from $Fm\ensuremath{-}3m$ to $C2/m$ with exchange striction and a type of magnetostriction (dipolar and roto magnetostriction). These unified viewpoints and the high-resolution neutron powder diffractometer enable us to construct an order-parameter vector diagram. The order-parameter vector diagram reveals distinguished order-parameter coupling and phase-transition characters by different ${\mathrm{\ensuremath{\Gamma}}}_{1}^{+}({A}_{g})$ and ${\mathrm{\ensuremath{\Gamma}}}_{2}^{+}({B}_{g})$ spin direction. Moreover, the experiment results show clearly that the ${\mathrm{CoO}}_{6}$ octahedral distortion and the Co magnetic moment couple through a magnetoelastic coupling ${\ensuremath{\epsilon}}_{\text{oct}}\ensuremath{\sim}{M}^{3}$, which is forbidden by time-reversal symmetry but allowed by the more general magnetic symmetry---the so-called rotation-time-reversal symmetry in the double antisymmetry space group. Rotation-time-reversal symmetry allows the coupling of odd-power polynomials in the spin vector and odd-power ones in the roto vector when both spin- and roto-axial vectors belong to the same irreducible representation in Landau free energy. Here, we show experimental evidence that the magnetic order parameter and static structural order parameter belong to the same irreducible representation in the materials. Experimental discovery of general magnetic symmetry opens a way to find the physics forbidden by time-reversal symmetry in condensed matter physics.

SPODI: High resolution powder diffractometer

The high resolution powder diffractometer SPODI (jointly operated by the Karlsruhe Institute of Technology and the Technische Universität München) is designed for structure solution and Rietveld refinement of crystal and magnetic structural parameters on polycrystalline powders. Instrumental specification (design, flexibility, peak shape, resolution etc.) as well as a variety of specialized sample environment equipment implemented for in-situ materials characterisation make the instrument attractive for studies of complex ordering phenomena.

Large-scale scientific facility at China Advanced Research Reactor for neutron scattering

As a complementary role to X-rays, neutrons provide a unique, non-destructive method. Neutron scattering techniques have been widely applied to the determination of the structural details and the dynamics of atomic arrangements in materials and matters. Large-scale scientific facility of neutron scattering has played an important role in basic research and industry. This paper reviews the outstanding characteristics of neutron probe, the development status of neutron scattering facilities abroad, and especially the progress of the first phase of Neutron Scattering Project at China Advanced Research Reactor (CARR). By now, ten instruments, including a High Resolution Powder Diffractometer (HRPD), a High Intensity Powder Diffractometer (HIPD), a Residual Stress Diffractometer (RSD), a texture diffractometer (TD), a four circle diffractometer (FC), two Triple Axis Spectrometers (TAS), a reflectometer (RF), a Small Angle Neutron Scattering instrument (SANS) and a High Frame-rate Neutron Imaging Test Station (HFNIT) have been constructed in cooperation with Peking University, Institute of Chemistry of Chinese Academy of Sciences (CAS), Institute of Physics of CAS, Juelich Center in Germany and the partner from Sweden. The construction of them has been completed and they are under commissioning. CARR has run more than 200 hours for adjusting and optimizing the instruments and some promising experimental results have been attained. As one of the most powerful high-flux reactor neutron sources in the world, CARR will ensure the development and application of neutron scattering in China.