Neutron and X-ray Scattering in Materials Science: Poster Session
Sponsored by: TMS Functional Materials Division, TMS: Chemistry and Physics of Materials Committee
Program Organizers: Michael Manley, Oak Ridge National Laboratory; Chen Li, University of California-Riverside; Jennifer Niedziela, Oak Ridge National Lab; Hillary Smith, Swarthmore College
Tuesday 5:30 PM
March 21, 2023
Room: Exhibit Hall G
Location: SDCC
Longitudinal Conical Magnetic Structure in Scandium Doped M-type Barium Hexaferrite: Surbhi Gupta1; 1Indian Institute of Technology, Bombay
M-type barium hexaferrites (BaM) have attracted a lot of attention due to their multiferroic and other functional properties. Doped M-Type Barium hexaferrite, BaFe12-xTxO19, where T = Sc with x = 2.5 has been investigated. XRD analysis reveals that the samples are in a single phase with space group P63/mmc. Magnetization curves in the temperature range of 5 K to 750 K indicate several transitions for the BaFe9.5Sc2.5O19. Transitions observed at lower temperatures indicate antiferromagnetic order. Temperature dependence neutron diffraction measurements performed at a wavelength of, λ = 2.315 Å, in the temperature range 3 K – 300 K. Magnetic satellite reflections start appearing at low angles on decreasing temperature, refinement of this magnetic reflection indicates the presence of conical magnetic structures at low temperatures. This indicates, that the direction of magnetic moments, compared with the parent compound, is no longer along the hexagonal c-axis.
L-55: Neutron Compton Scattering of Hydrogen in Zirconium: Brent Heuser1; Timothy Prisk2; Alexander Kolesnikov3; Garrett Granroth3; Jun-Li Lin1; 1University of Illinois; 2NIST; 3ORNL
We report on deep inelastic neutron scattering measurements of the zero point energy of interstitial hydrogen in zirconium using SEQUOIA at the Spallation Neutron Source. In addition, the vibrational modes were characterized in the same set of measurements. The dynamic structure factor exhibits dispersionless bands of the fundamental and higher optical phonon modes. At 6.2eV incident energy the recoil dispersion of ground state hydrogen is captured. Analysis of the recoil dispersion is consistent with a harmonic ground state of hydrogen. Anharmonic effects are evident in the excited states of hydrogen via the multiphonon bands. The hydrogen (proton) kinetic energy in zirconium is measured as E=109.0eV in ZrH2 and as 113eV in ZrH0.0155 at 6K.
L-56: Plastic Scintillators Using Nanocrystal Emitters: Gerard Ducharme1; Amanda Graff1; 1Los Alamos National Lab
Plastic scintillators suffer from low efficiency and poor signal separation, hampering source discrimination. Inclusion of wavelength shifters and heavy atom dopants have allowed for improvements in these devices. Our research has shown that inclusion of II-VI based core-shell giant quantum dots (gQDs) into the polymer matrix greatly improves the luminescence efficiency and signal separation over previous fluor doped polymeric scintillators. The efficiency arises from a combination of the heavy atom quantum dots that are capped to prevent self-attenuation and can more easily interact with stimuli than traditional fluors, as well as the presence of a triplet-triplet annihilating fluor which boosts emission efficiency significantly. The goal of this research is to develop an additive manufacturing process to more consistently and easily form highly efficient and cost-effective scintillators.
L-68: Quantification of Nanoscale Precipitation in Al Using SAXS and Electron Microscopy-based Automatic Particle Counting Software Techniques: Alyssa Stubbers1; Ning Zhu2; Luke Brewer2; Anthony Naccarelli3; Timothy Eden3; John Balk1; 1University of Kentucky; 2University of Alabama; 3Pennsylvania State University
Quantification of precipitate size distributions in Zn-containing Al alloys is challenging due to limited precipitate size (< 20 nm) and dense precipitate fields. Manual microscopy methods are time consuming and have difficulty identifying individual precipitates for measurement in large precipitate fields. Small angle x-ray scattering (SAXS) provides an alternative pathway for analysis of precipitate sizes, spacing, and volume fraction data that can provide insight on precipitate structures and how they relate to mechanical properties of the material. This work evaluates SAXS as a complement and to TEM particle measurement techniques, and highlights challenges of this technique compared to conventional microscopy characterization. This comparison is applied to AA7050-T7451 material heat treated over a range of times and temperatures. Evaluation of TEM-based automatic particle counting software as a comparable method to scattering is also considered. The analyses from each technique will be compared and contrasted, with a discussion of their relative merits.
L-57: Recent Developments at the Forming and Shaping Technology (FAST) Beamline: Katherine Shanks1; Amlan Das1; 1Cornell University
The Forming and Shaping Technology (FAST) beamline at the Cornell High Energy Synchrotron Source (CHESS) provides x-ray tools for investigating the performance and processing of structural materials, with a particular focus on in-situ and time-resolved measurements. Both imaging and diffraction methods are supported, primarily near- and far-field high-energy diffraction microscopy (HEDM), transmission powder diffraction, and micro-computed tomography. Beamline design, capabilities and applications will be described, along with recent developments including: the design and commissioning of a laser powder bed fusion system developed in collaboration with NIST for in-situ diffraction measurements during AM builds, the deployment of advanced area detector technology to support time-resolved experiments at kHz – MHz rates, and progress towards infrastructure for streamlined on-the-fly screening and analysis of large datasets.
L-58: Residual Stress Mapping in a Dissimilar Metal Weldment Using Neutron Diffraction: Brent Heuser1; Weicheng Zhong2; Jun-Li Lin1; Yan Chen2; Zhen Li1; Ke An2; Benjamin Sutton3; 1University of Illinois; 2ORNL; 3EPRI
The engineering diffractometer VULCAN was used to quantify residual stress in a SA508-304L weldment with 309L butter and 308L groove filler material. The weldment was nuclear grade and fabricated by EPRI. Residual stress is a first order effect in irradiation assisted stress corrosion cracking of weldments in nuclear power plants. The entire heat affected zone as well as the base metals were scanned. In addition, a comb dnot sample was measured. Large tensile residual stresses and large gradients are observed near the SA508-309L butter interface. This coincides with observed cracking in hot water immersion tests with proton irradiated material. Discussion will focus on correlations between residual stress, hardness, microstructure, radiation damage, and cracking.
L-59: Thermodynamics of Elinvar Behavior: An Experimental Study with Nuclear X-ray Scattering: Pedro Guzman1; Stefan Lohaus1; Camille Bernal-Choban1; Brent Fultz1; 1California Institute of Technology
Fe-45%Ni exhibits a temperature-independent bulk modulus over a wide temperature range at ambient pressure; this anomaly is known as the “Elinvar effect”. We performed X-ray diffractometry experiments at several conditions of pressure and temperature to measure the bulk modulus (B = -V dp/dV) of Fe-45%Ni, confirming it has a negligible temperature dependence at low pressures. Next, we performed nuclear resonant inelastic X-ray scattering and nuclear forward scattering experiments at room temperature and several conditions of pressure to probe the phonon spectrum and magnetism of Fe-45%Ni. These measurements allow us to quantify the vibrational and magnetic entropies and investigate the effects of vibrational and magnetic degrees of freedom on the bulk modulus. At pressures of Elinvar behavior, we report a cancellation of phonon and magnetic entropies that results in the weak temperature dependence of the bulk modulus. This work was supported by the National Science Foundation under Grant No. 1904714.
Unveiling Structural Disorders and Their Correlation with Ionic Conductivity in a Potential Na-Ion Battery Material: Na2Mn3O7: Bikash Saha1; Anup Bera2; Seikh Yusuf2; 1Bhabha Atomic Research Centre; 2Bhabha Atomic Research Centre
In the present study, crystal structure and ionic conduction properties of the technologically important 2D layered Na-ion battery material Na2Mn3O7 have been investigated by x-ray diffraction, neutron diffraction and impedance spectroscopy. Our study reveals the layered crystal structure contains a significant amount of stacking faults of the manganese-oxygen Mn3O72- layers as evident from the asymmetric broadening of selective nuclear Bragg peaks in the neutron diffraction pattern. Comprehensive impedance spectroscopy study and its data analysis in the form of dc-conductivity, ac-conductivity, electrical modulus, and dielectric constant reveal a long-range Na-ionic conductivity. The role of stacking faults on the Na-ion conduction properties has been brought out by investigating the samples that were prepared with varying annealing time (4, 14, and 28 h). The derived results establish a correlation between the stacking faults and the ionic conductivity where the conductivity increases with the reducing stacking faults of the crystal structure.