allthough we are all more or less powder people, we obviously have
different interests. In fact, UnitCell is one of MY most helpful tools,
when I try to do a phase analysis of my routine diffractogrammes and when I
work out the input files for the Rietveld-refinement (maybe, because it
existed for the MAC first :-) ).
I do mostly have an idea of the miller-indices just from regarding relative
intensities; the reflections are like fingerprints (this holds at least for
relatively simple cubic, tetragonal and orthorhombic structures and some
hexagonal) given that you know other details of the sample ( e.g.
stoichiometric composition; VERY useful). Actually, it's just a kind of
Hanawalt-search going on in your head.
You might call that irrational, but in fact it is just another way to solve
the problem. A more chemical way to look at things ;-).
For example: You will probably NOT yield a hexagonal perovskite stacking
variant using Ca or any reare earth as A-cation. Or take the
(200)-(121)-(002)-(030) set of the orthorhombic perovskites; I worked that
one out during my diploma thesis and since then, I guess, I will allways
remember this structure, when I see that combination of intensities
somewhere around 31-35° 2Q (with Cu Kalpha radiation, to be precise).
I must admit, that UnitCell is probably not the tool you will use to
resolve a completely unknown structure. And you should perhaps not tell
someone completely unaware of crystallography, that you don't need any
information to index diffractogrammes.
Given the limitation to Rietveld stuff (and related; for sure not SOCCER
;-) ) of the list, Simon should probably have posted his message on the
xtal-list, but that doesn't matter the fact, does it?
Greetings from Bordeaux
Carsten
Carsten Schinzer ---------------------------------------
Institut de Chimie de la Matiere Condensee de Bordeaux
87, Avenue du Docteur A. Schweitzer
F-33608 PESSAC
fon +33 556 84 2650 (poste 7397) fax +33 556 84 2761
http://www.icmcb.u-bordeaux.fr/~schinzer
--------------------------------------------------------