In a message dated 12/31/1999 1:24:41 AM Pacific Standard Time,
[EMAIL PROTECTED] writes:
<< Seems to me that powder diffractionists in the 1950-70 years, had too
much confidence in powder diffraction.............. thus delivering a poor
uncomplete database to real users all those past long years............
However, we are scientists.......>>
I do not think so. One has to take the PDF database by what it really is: a
collection of XRD powder patterns for expedient compound and phase
identification. The emphasis has always been on careful observation! In how
much this observation agreed or disagreed with true cystallographic nature of
the material has so far been a second priority. Look in the mineral subfile,
actual traces of patterns observed are published for various clays. I find
this extremely helpful for a first approach to solve unknown patterns! But I
don't know any 'real user' who would rely on PDF data only to do serious
crystallography. Obviously, the time has come now to close this gap and all
the efforts going into such an endeavor are truly appreciated. And one should
not hestitate to concede deserved credit to the pioneers who started this
database and did a great service to analytical chemistry over decades. (The
fact that the PDF database seems overpriced is a different matter!).
L. Keller
