Non-Ambient Diffraction Subcommittee Agenda and Minutes

ICDD High Pressure and Temperature Diffraction (Non-Ambient Diffraction) Subcommittee
Wednesday, 20 March 2002
1:00 - 2:00 p.m.
ICDD Headquarters, Conference Room A
Chairman: Charles Prewitt

C. Prewitt as Chairman made a number of opening remarks; he informed the attendees of the changes that are happening in the high temperature and pressure community. He also suggested that there was currently more interest within the ICDD community in high-temperature than in high-pressure diffraction and encouraged anyone with any interest in high-temperature diffraction to become involved.

As there were no minutes taken at the last meeting, these were not discussed.
The mission statement was discussed and the current version is reproduced at the end of the minutes.

All members of the subcommittee received a questionnaire previous to the meeting regarding the role of the ICDD High Pressure and Temperature Diffraction Subcommittee. Eight members responded and several of their concerns were discussed. These included:

  • The need for temperature calibration standards and one or more descriptions of how these standards should be used. This could be expanded to include as complete as possible data on materials that are good temperature standards.
  • The development of the database as a means of identifying phases obtained or occurring under non-ambient conditions.
  • The addition to the database of non-diffraction information that includes, for example, thermal expansion coefficients and phase stability regions. J. Faber was asked if this is possible and he said 'yes'.
  • The addition of titles of papers to the ICDD database. It was suggested that titles often contain useful information and would allow users to judge their interest in the paper and its contents. A motion was passed unanimously requesting that the Technical Committee consider this addition (Motion #1 below).
  • ICDD software should allow searching on the non-ambient temperature/pressure flags already in the database. This clearly will be possible with PDF-4, but current software using PDF-2 generally does not have this capability, although the flags are present in the File.
  • It may be necessary to limit the number of high temperature/pressure materials in the database. This concern arises from the large number of data sets that can be collected during a synchrotron/neutron session. The point was also made that data are collected using different methods making comparison of the intensities difficult. The question, "whether energy dispersive data should be included in the database, and what is the usefulness of these data" was discussed.
  • The subcommittee should review and report on problems with non-ambient data, both internal (HQ) and external (journals), and the difficulties with 'duplicate' but 'different' patterns.
  • Should there be a standard method for reporting the pressures involved in experiments? For example, a material might be synthesized at one pressure, annealed at another, and quenched to ambient conditions. How much of this information should be included in the PDF?

S. Misture volunteered to look into methods of combining a number of individual data sets or databases into one universal form. The locations of a number of useful databases were suggested.

A second motion to change the name of the committee was approved (Motion #2 below). This was agreed upon as a way to include the low temperature community in subcommittee activities.

Motion #1: The High Pressure and Temperature Diffraction Subcommittee moves that the full titles of references be provided in the PDF database.

Motion #2: The High Pressure and Temperature Diffraction Subcommittee moves that the name of the Subcommittee be changed to Non-Ambient Diffraction Subcommittee.

Mike Bennett, Acting Secretary

High Pressure and Temperature Diffraction Subcommittee Mission Statement
The High Pressure and Temperature Diffraction Subcommittee of the International Centre for Diffraction Data is organized to facilitate the use of the PDF by the high-pressure, high-temperature diffraction community. It makes recommendations to the ICDD about how diffraction data obtained at non-ambient conditions should be represented in the PDF, and suggests specific research activities that could result in production of new non-ambient patterns for the PDF. It also maintains contact with various research and administrative groups throughout the world to exchange information about new developments in HPT diffraction techniques and results.