Neutron Diffraction
(PDF-4+ 2016, PDF-4/Minerals 2016)

neutron
Identification of a two phase fuel cell composition performed using the PDF-4+ program SIeve+. The experimental data are courtesy of the OPAL neutron diffractometer at the Bragg Institute ANSTO, Sydney, Australia.

In 2014, we announced our neutron diffraction analysis capability based on constant wavelength neutron diffraction. In 2015, we added the ability to analyze deuterated materials and continued to produce neutron pattern references for newly discovered materials. Major additions made to the SIeve/SIeve+ analysis programs to quantify and identify materials can be applied to neutron, electron, synchrotron, and X-ray data.

New Capabilities: Time-of-Flight (TOF) Neutron Diffraction Pattern Simulations

Neutron powder diffraction is a useful tool because elemental scattering contrast is quite different when compared to X-rays. Elements in the periodic table often have quite different scattering amplitudes (the scattering cross sections are not strictly proportional to atomic number, Z and isotope).

Unlike standard laboratory X-ray sources, synchrotron sources, nuclear research reactors and pulsed neutron sources are sited at national facilities (available world-wide). One of the initiatives of the ICDD is to expand the content of the PDF-4 to include powder diffraction from facilities outside the X-ray laboratory.

Even though constant wavelength neutron sources continue to be exceedingly productive, pulsed neutron sources continue to be at the technology edge. The basic rationale for this is that current high flux reactors use limiting technology to achieve the power density required to support neutron powder diffraction. The next step is to use extremely intense pulses of polychromatic (white beams) neutrons.

For Release 2016, the PDF-4 software allows users to:

  • Import instrument parameters provided by time-of-flight (TOF) neutron facilities (in either GSAS or FullProf formats).
  • Simulate TOF neutron powder diffraction patterns using these imported instrument parameters (provided the database entry has atomic coordinates).
  • Import raw TOF neutron diffraction patterns (in either d-spacing or TOF units) for visual comparison or full pattern matching to simulated diffraction patterns from the database.
  • Perform isotopic substitution for both constant-wavelength (CW) and time-of-flight (TOF) neutron diffraction pattern simulations.

Raw TOF neutron diffraction pattern (La B6) plotted against a PDF-4 simulated diffraction pattern found using full pattern matching.tof

Full pattern matching results for La B6 using TOF neutron diffraction patterns.
tof2
Isotoptic substitution for constant-wavelength (CW) neutron diffraction pattern simulations.tof3

Technical Bulletins

time of flight

Synchrotron Neutron User's GUide

Fast Facts on ICDD’s Neutron Diffraction Capability

Developed via an ICDD member task team of neutron diffractionists

273,842 entries calculated for neutron diffraction

Strong and long line index creation for rapid searches

I/Ic generated for neutron data for use in quantitative analysis by RIR

Instrument function wizard to simulate digital patterns based on international neutron facilities

Interfaces to SIeve+ to enable neutron data search and identification by several different algorithms

2015 Technical Presentations on Neutron Diffraction

2015 Denver X-ray Conference

Fundamentals of Neutron Diffraction (Workshop)
Organizer & Instructors:
P.S. Whitfield, Oak Ridge National Laboratory, Oak Ridge, TN, whitfieldps@ornl.gov
T.G. Fawcett, International Centre for Diffraction Data, Newtown Square, PA, fawcett@icdd.com
A. dos Santos, J.R. Bunn, Oak Ridge National Laboratory, Oak Ridge, TN
J. Faber, Faber Consulting Inc., Thornton, PA

2014 Technical Presentations on Neutron Diffraction

ICDD Workshop EPDIC 14

“Materials Characterization Capabilities Using the Powder Diffraction File™”

“New Neutron Diffraction Data Analysis Capabilities in PDF-4+” - T. G. Fawcett, ICDD, Newtown Square, PA

2014 Denver X-ray Conference

New Neutron Diffraction Data Capability in the ICDD PDF-4+ 2014 Relational Database,” Advances in X-ray Analysis, 58, 77-89, Faber, J., Crowder, C. E., Blanton, J., Kabekkodu, S. N., Blanton, T. N., Fawcett, T. G.,   Gourdon, O. (2015)

“A Powder Diffraction Database for All Radiations” (poster) - C.E. Crowder, S. Kabekkodu, J. Blanton, R. Vithayathil, V. Bosnic, D. Sagnella, K. Zhong, T. Blanton, T. Fawcett, ICDD, Newtown Square, PA