segre at iit.edu
Tue Feb 3 21:46:38 CST 2009
In my experience, nanoparticles tend to become perfect crystals because
the strain energy per atom in the cluster is too large to support a dopant
which severely distorts the structure. It is possible that a dopant like
Er is simply expelled from the nanoparticle. In the bulk, there are more
mechanisms for relaxing the strain and, more importantly, there are many
more atoms available over which to spread the strain energy.
>From the bond distances you quote, the Er may indeed be on the surface.
Did you notice any change in the spectrum as a function of time?
On Tue, 3 Feb 2009, Eugenio Otal wrote:
> Hi everybody,
> thanks for your time, knowledge and pacience.
> The first shell is can be fitted by 2 sub shells with this composition:
> n_first_1 = 2.4702860
> r = 1.782161
> n_first_2 = 9.2476950
> r = 2.342539
> This is really far from Zn in ZnO, is closer to Er(OH)3, with 8 between 2.40
> and 2.43 and ErOOH presents 7 neighbors between 2.26 and 2.45, with
> something like 2 sub-shells. Er2O3 has two sites with octahedral simmetry,
> one is perfectly Oh and the other distorted with 2.21 to 2.36 for Er-O.
> I chequed the doping element incorporation and found that what I suppose to
> be 1% is in fact 0.6% (by ICP quantification) the incorporation is less I
> though. Maybe that is the reason to do not find call parameters change.
> What kind of difference could I find between nanoparticles and bulk for
> Cheers, euG
Carlo U. Segre -- Professor of Physics
Associate Dean for Special Projects, Graduate College
Illinois Institute of Technology
Voice: 312.567.3498 Fax: 312.567.3494
segre at iit.edu http://www.iit.edu/~segre segre at debian.org
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