Re: [Ifeffit] Linear Combination Fitting using ATHENA

Hi all! I am out of my place and I can not check it now, but I believe that in the database of XAFS (or something like that) there are some spectra of maghemites obtained by Lytle long time ago. Best regards Maria Elena Montero Cabrera El ago 13, 2013 3:38 a.m., "Teck Kwang Choo" escribió:

Hi all,

@Drew Latta: I was wondering why the end members should be magnetite and maghemite. Is it because they are both of inverse-spinel structure, the difference only being that the latter has all Fe completely oxidized into Fe(III)? Would you be able to provide the standard spectra to me if that is the case? Thanks very much!

Previously I have only thought of using hematite (alpha-Fe2O3) and FeO as end-members, both representing Fe(III) and Fe(II) respectively without giving much thought to the structure Fe takes. I also had my doubts using magnetite (Fe3O4) as a standard as it is a mixture of both Fe (II) and Fe (III). But thanks to the insights Drew has given, I now think I should take the Fe-coordination environment into account with the use of magnetite and maghemite as standards.

@Alexandre and Matthew: I have obtained Mossbauer spectra of some of my samples but like Drew said, it is not straightforward at this point in time. Will see what I can do with the data I have!

Thanks for all your responses! It is greatly appreciated! This forum has been more helpful than I thought!

Teck Kwang

On 13 August 2013 01:34, Matthew Marcus wrote:

...

While it's true that Mossbauer is the gold standard for Fe valence determination, access to the technique isn't all that common, and I don't know of any facility that can do it on a micro scale. Is there one? mam

On 8/12/2013 7:01 AM, Alexandre dos Santos Anastacio wrote:

...

Hello,

maybe that fingerprinting technique would be Mossbauer spectroscopy. The Fe(II)/Fe(III) ratio comes easily and also there are lots of papers about Mg-ferrite, an example:

10.1109/TMAG.2009.2018880 <http://dx.doi.org/10.1109/**TMAG.2009.2018880http://dx.doi.org/10.1109/TMAG.2009.2018880

...

Alexandre.

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