Dear Anatoly,
The problem is even more complex:
-
there is one Co2+ species in tetrahedral environment;
-
there are small (20 - 100 atoms) metallic clusters;
-
there is an intermediate Co+1 like species in tetrahedral coordination.
All these species may be present in some of the samples. Plus,
I assume the
Co-O distance between Co in small metallic
clusters and oxygen in the
silica is different than that
between Co2+ ions and O2- ions in the cobalt
oxide -
like compound, which adds to the complexety.
We feel
like we're chasing our tail with this thing...:)
Dragos
-----Original Message-----
From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov]On Behalf Of Scott Calvin
Sent: Friday, May 06, 2005 5:09 PM
To: XAFS Analysis using Ifeffit
Subject: Re: [Ifeffit] Need an adviceHi Matt, The quote below is where I got the idea that Steven was interested in size-determination of nanoparticles, but I may have misunderstood...maybe he meant to use the fraction of oxide as a marker for the surface to volume ratio? In any case, that still makes me think that he expects to have nanoscale particles... --Scott Calvin Sarah Lawrence College At 03:12 PM 5/5/2005 -0400, Steven wrote: >>>> However, if what we have is closer to a physical mixture of small Co metal particles and Co oxide particles, it would seem that it would be more appropriate to analyze separately the windowed Co-O and Co-Co peaks in R-space, to somehow normalize the Co-Co to the fraction of metal in the sample and use this as a qualitative measure of metal particle size.