Electronically focused time-of-flight powder diffractometers at the intense pulsed neutron source

Abstract

Two time-of-flight powder diffractometers have operated at the Intense Pulsed Neutron Source (IPNS) since August 1981. These instruments use dedicated microcomputers to focus time-of-flight events so that data from different detectors can be summed into a single histogram. Thus, large multidetector arrays can be employed at any scattering angle from 12 to 157 °. This design permits data to be collected over a uniquely wide range of d spacings while maintaining high resolution and count rates. The performance of the two instruments is evaluated by analyzing data from a standard A1203 sample by the Rietveld method. These instruments provide the capability for moderate-to high-resolution measurements with the duration of a typical run being a few hours.

Rietveld texture analysis of Dabie Shan eclogite from TOF neutron diffraction spectra

“…Neutron diffraction experiments were performed on the general purpose powder diffractometer (GPPD) (Jorgensen et al, 1989) at the IPNS of Argonne National Laboratory. Since the neutron source is pulsed, detectors measure neutron scattering as a function of TOF of neutrons, rather than the scattering angle.…”

Thermal expansion and compressibility in superconductingNaxCoO2∙4xD2OJorgensen1, Avdeev2, Hinks3 et al. 2005Phys. Rev. BSelf Cite6000View full textAdd to dashboardCite

“…Thus, the temperature-and pressure-dependent data differ in resolution (∆d/d≈0.003 in back scattering and 0.005 at 90°). [18] The lower-resolution data taken at pressure are more susceptible to systematic errors from the diffuse scattering resulting from short-range supercell ordering. [12] In an attempt to explore the size of this effect, we performed additional refinements in which the major regions of diffuse scattering were excluded.…”

Spin-state transitions in PrCoO3studied with neutron powder diffraction

“…5,19,20 Highresolution neutron powder diffraction measurements were performed from 12 to 600 K using the Special Environment Powder Diffractometer (SEPD) at IPNS, Argonne National Laboratory. 21 Structural refinements were carried out using the GSAS program with the EXPGUI interface, 22 in which isotropic thermal parameters (U iso ) of Co and Pr and anisotropic thermal parameters (U aniso ) for oxygen were used. The refinement with U aniso for oxygen was found to improve significantly the fitting agreement (an improvement of more than 8% at high temperatures), indicating the importance of the anisotropic thermal motions.…”