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RE: contribution to working group

Dear David and fellow members:

Thoughts inspired by Jean-Claude's message this morning:

7.1.  I agree with him that, at least for inorganic compounds (including
intermetallics), composition should be an essential part of any internal
identifier if pertinent information residing in all types of databases is
thereby to be accessible.

Regarding solid solutions, since they necessarily involve a range of
with properties that may be dependent on a very narrow range, the inclusion
of a
numerical indication is probably obligatory. For example, piezoelectric PZT
widely used industrially) may be represented as Pb[Zr(1-x)Ti(x)]O3 with
electromechanical properties of maximum value in the range x ~ 0.5 to 0.6. A
given paper may well refer to a highly specific value of x in this range,
the identifier must be able to retrieve that paper as well as others with
composition. A possible problem that an external identifier will have to
is in being either too broad or too narrow in retrieving a given mixed

7.2   It would be more user-friendly if we could devise an approach in which
either an internal or external identifer were acceptable.

7.3   I prefer to leave this question for comment by those members who are
database knowledgeable.

7.4   Jean-Claude has identified a problem of considerable importance. There
are clear advantages in formulating identifiers that are universally
to all kinds of crystalline phases, and I would hope we can achieve such a

7.5   If a hybrid system proves possible, and in principle there seems to be
reason why not, that might eliminate many problems for us.

7.6   I look forward to proposals by others more expert than I in this

Best wishes.

Prof. S. C. Abrahams
Physics Department
Southern Oregon University
Ashland, OR 97520

Fax: (541) 552-6415   Tel: (541) 482 7942
Email: sca@mind.net

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