[Ifeffit] Ifeffit Digest, Vol 160, Issue 17

Fri Jun 24 00:19:34 CDT 2016

Hello Fuxiang,

A small suggestion

Please also don't forget to try multiple edge data fitting if you already
measured your data in both Fe and Ni edge, this may actually reduce the
number of parameters to use. You need just on parameter  Fe-Ni/Ni-Fe should
be same when looking from both atom

Hope it helps,

Ditty
On Jun 23, 2016 23:48, <ifeffit-request at millenia.cars.aps.anl.gov> wrote:

> Send Ifeffit mailing list submissions to
>         ifeffit at millenia.cars.aps.anl.gov
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> or, via email, send a message with subject or body 'help' to
>         ifeffit-request at millenia.cars.aps.anl.gov
>
> You can reach the person managing the list at
>         ifeffit-owner at millenia.cars.aps.anl.gov
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Ifeffit digest..."
>
>
> Today's Topics:
>
>    1. Re: How to input atoms in solid solution for Artemis
>       (Scott Calvin)
>    2. Re: How to input atoms in solid solution for Artemis
>       (Fuxiang Zhang)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 23 Jun 2016 16:23:36 -0400
> From: Scott Calvin <dr.scott.calvin at gmail.com>
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
> Subject: Re: [Ifeffit] How to input atoms in solid solution for
>         Artemis
> Message-ID: <F8C55BBE-4E8E-436E-97C4-35387D9B5B02 at gmail.edu>
> Content-Type: text/plain; charset="utf-8"
>
> One additional thought:
>
> Distinguishing Ni-Ni and Ni-Fe by creating two different feff paths and
> fitting the spectrum as a mixture of the two is very difficult, to put it
> mildly, as both Anatoly and Matt indicated.
>
> But the bond length determined by your fit may be able to give you a clue,
> particularly when compared to appropriate standards. Depending on the
> details of your structure, the average bond length may depend on the
> fraction of sites occupied by iron to a degree which is measurable by
> EXAFS. Even if you simply use a nickel-nickel scattering path in feff to
> model your structure, differences in bond length could be indicative of
> changes in site occupancy.
>
> Ideally, this could be done by creating a series of standards with known
> iron-nickel ratios, fitting the bond length for each, and then comparing a
> fit of a sample with a similar structure but unknown iron-nickel ratio to
> the results for the standards.
>
> ?Scott Calvin
> Sarah Lawrence College
>
> > On Jun 23, 2016, at 3:41 PM, Fuxiang Zhang <zhangfx at umich.edu> wrote:
> >
> > Hi, Matt and Anayoly,
> > Thank you very much for the help.
> >
> > Fuxiang
> >
> > On Thu, Jun 23, 2016 at 1:51 PM, Anatoly I Frenkel <afrenke2 at yu.edu
> <mailto:afrenke2 at yu.edu>> wrote:
> > Whatever you decide to do, remember that Ni Ni and Ni Fe pairs look very
> similar by EXAFS, so it does not matter how you end up doing it.
> > You can as well use pure Ni but you may want to consider both fcc and
> bcc structure for making the model because the alloy may end up to be
> either that or that, especially if it is a nanoalloy.
> >
> > Anayoly
> >
> >
> >
> > Sent from my Verizon Wireless 4G LTE Tablet
> >
> >
> > -------- Original message --------
> > From: Fuxiang Zhang <zhangfx at umich.edu <mailto:zhangfx at umich.edu>>
> > Date: 6/23/2016 12:51 PM (GMT-05:00)
> > To: ifeffit at millenia.cars.aps.anl.gov <mailto:
> ifeffit at millenia.cars.aps.anl.gov>
> > Subject: [Ifeffit] How to input atoms in solid solution for Artemis
> >
> > Hi, All,
> > I am new in using EXAFS techniques. Just wondering how to input atomic
> structure of NiFe solid solution to Artemis. It has a simple Ni-structure,
> but both Ni and Fe occupy the same site. If I use partial occupancy,
> Artemis program does not allow. Anyone can give me an ideal?
> > Also the coordination number N cannot be refined in this simple system
> (12), is that right? In fact I just want to get the N through the fitting
> of EXAFS because of the partial occupancy.
> > Thank you very much
> >
> > Fuxiang Zhang
> >
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov <mailto:
> Ifeffit at millenia.cars.aps.anl.gov>
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit <
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit>
> > Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit <
> http://millenia.cars.aps.anl.gov/mailman/options/ifeffit>
> >
> >
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> > Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
>
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160623/f98683ca/attachment-0001.html
> >
>
> ------------------------------
>
> Message: 2
> Date: Thu, 23 Jun 2016 17:47:00 -0400
> From: Fuxiang Zhang <zhangfx at umich.edu>
> To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
> Subject: Re: [Ifeffit] How to input atoms in solid solution for
>         Artemis
> Message-ID:
>         <CAP=
> koc6bTHKqDGk30bqQPH+56apQ8Jn5g0gCxhMRJbqhMhc38A at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Hi, Scott,
>
> In fact, I have a series of single crystal Ni-Fe alloys (Fm-3m) with known
> atomic ratio, and measured both Fe and Ni edges for samples and standards.
> I just want to see if there's any difference between the local bonding
> environment of Fe and Ni, such as R, N and sigma2. Now using the suggested
> method by Matt by changing atoms in FEFF.inp file, I can only get ss, deltr
> and E0 from fitting (I don't know how to refine N and R). But the fitting
> with Ni (or Fe) edge can only generate the same R and deltr for Ni-Ni and
> Ni-Fe pairs. Fitting the edges of Ni and Fe will yield a little difference
> in the R and deltr. Which results should I believe, or something wrong I am
> using the program because I cannot generate different R for Ni-Ni and Ni-Fe
> pairs with the same data set.
> Many thanks for your suggestions and helps.
>
> Fuxiang Zhang
>
> On Thu, Jun 23, 2016 at 4:23 PM, Scott Calvin <dr.scott.calvin at gmail.com>
> wrote:
>
> > One additional thought:
> >
> > Distinguishing Ni-Ni and Ni-Fe by creating two different feff paths and
> > fitting the spectrum as a mixture of the two is very difficult, to put it
> > mildly, as both Anatoly and Matt indicated.
> >
> > But the bond length determined by your fit *may* be able to give you a
> > clue, particularly when compared to appropriate standards. Depending on
> the
> > details of your structure, the average bond length may depend on the
> > fraction of sites occupied by iron to a degree which is measurable by
> > EXAFS. Even if you simply use a nickel-nickel scattering path in feff to
> > model your structure, differences in bond length could be indicative of
> > changes in site occupancy.
> >
> > Ideally, this could be done by creating a series of standards with known
> > iron-nickel ratios, fitting the bond length for each, and then comparing
> a
> > fit of a sample with a similar structure but unknown iron-nickel ratio to
> > the results for the standards.
> >
> > ?Scott Calvin
> > Sarah Lawrence College
> >
> > On Jun 23, 2016, at 3:41 PM, Fuxiang Zhang <zhangfx at umich.edu> wrote:
> >
> > Hi, Matt and Anayoly,
> > Thank you very much for the help.
> >
> > Fuxiang
> >
> > On Thu, Jun 23, 2016 at 1:51 PM, Anatoly I Frenkel <afrenke2 at yu.edu>
> > wrote:
> >
> >> Whatever you decide to do, remember that Ni Ni and Ni Fe pairs look very
> >> similar by EXAFS, so it does not matter how you end up doing it.
> >> You can as well use pure Ni but you may want to consider both fcc and
> bcc
> >> structure for making the model because the alloy may end up to be either
> >> that or that, especially if it is a nanoalloy.
> >>
> >> Anayoly
> >>
> >>
> >>
> >> Sent from my Verizon Wireless 4G LTE Tablet
> >>
> >>
> >> -------- Original message --------
> >> From: Fuxiang Zhang <zhangfx at umich.edu>
> >> Date: 6/23/2016 12:51 PM (GMT-05:00)
> >> To: ifeffit at millenia.cars.aps.anl.gov
> >> Subject: [Ifeffit] How to input atoms in solid solution for Artemis
> >>
> >> Hi, All,
> >> I am new in using EXAFS techniques. Just wondering how to input atomic
> >> structure of NiFe solid solution to Artemis. It has a simple
> Ni-structure,
> >> but both Ni and Fe occupy the same site. If I use partial occupancy,
> >> Artemis program does not allow. Anyone can give me an ideal?
> >> Also the coordination number N cannot be refined in this simple system
> >> (12), is that right? In fact I just want to get the N through the
> fitting
> >> of EXAFS because of the partial occupancy.
> >> Thank you very much
> >>
> >> Fuxiang Zhang
> >>
> >> _______________________________________________
> >> Ifeffit mailing list
> >> Ifeffit at millenia.cars.aps.anl.gov
> >> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> >> Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
> >>
> >>
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> > Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
> >
> >
> >
> > _______________________________________________
> > Ifeffit mailing list
> > Ifeffit at millenia.cars.aps.anl.gov
> > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> > Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
> >
> >
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160623/e80e582d/attachment.html
> >
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
>
>
> ------------------------------
>
> End of Ifeffit Digest, Vol 160, Issue 17
> ****************************************
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20160624/9dfd8a01/attachment-0001.html>