Dear all, Happy New Year! I am dealing with the fitting of NaMn0.3Fe0.4Ni0.3O2 second shell. I have Mn, Ni, and Fe at 2.9772Å and Na at 3.1859Å, showing only one shell. If I use any of the transition metals (dZ <5) for fitting the second coordination shell. fitting is fine, but when I introduce the Na path, the fitting has no sense, CN_Na grows and also its error. Even including Na, I have Nvary = 10 and Ninp = 13.98, so I am getting out of ideas and nothing helpful in the ifeffit Archive until now. Is there any strategy for dealing with mixed second coordination shells? I am attaching the file exported from Larch and the cif file. Best regards. (^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=) Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates ¯\_(ツ)_/¯¯\_(ツ)_/¯ Who is John Galt? ¯\_(ツ)_/¯¯\_(ツ)_/¯
Hi Otal, I ran a quick FEFF simulation just to see what is present under that second peak in the FT. There are many more shells than just TM and Na...e.g. There is significant multiple scattering and another backscattering peak (Fe-O) at 3.6Angstroms. All of these are going to spread underneath that peak in the FT. You might also be getting some interference from the 4.07A MS stuff. It doesn't seem a surprise that just including TM and Na is giving problems. What is your high-R cutoff? Have you tried including multiple-scattering or that 4th backscattering contribution? cheers, Robert On 2024-01-09 12:06 a.m., Otal Eugenio wrote:
Dear all, Happy New Year! I am dealing with the fitting of NaMn0.3Fe0.4Ni0.3O2 second shell. I have Mn, Ni, and Fe at 2.9772Å and Na at 3.1859Å, showing only one shell. If I use any of the transition metals (dZ <5) for fitting the second coordination shell. fitting is fine, but when I introduce the Na path, the fitting has no sense, CN_Na grows and also its error. Even including Na, I have Nvary = 10 and Ninp = 13.98, so I am getting out of ideas and nothing helpful in the ifeffit Archive until now. Is there any strategy for dealing with mixed second coordination shells? I am attaching the file exported from Larch and the cif file. Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp mailto:eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates https://sites.google.com/view/zettsu-laboratory/news-updates
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Dear Robert,
Thanks for your detailed answer.
I am cutting at R=3.35. I also tried to go up to 4.0 to provide more
freedom and to include the SS TM-O at 3.6.
It seems that including MS was not fruitful at the moment. I found the
contribution very tiny, Importance < 10.
I included the path at 3.6, and it fits well, but when I include the Na,
the CN_Na goes to high values (>10) and errors (~+/- 50)
I also tried to restrict the CN of TM to force the Na to take place and get
good results. Also useless.
I was checking the data in R_real and the TM and Na paths. I see the TM
path is in phase while the Na path is not. I wonder if this is affecting
the fit. How should I constrain the fitting to solve this situation?
Best regards.
[image: image.png]
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL
Assistant Professor
Dept. of Materials Chemistry
Shinshu University
4-17-1 Wakasato, Nagano 380-8553, JAPAN
eugenio_otal@shinshu-u.ac.jp
https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
On Wed, Jan 17, 2024 at 1:24 AM Robert Gordon
Hi Otal,
I ran a quick FEFF simulation just to see what is present under that second peak in the FT. There are many more shells than just TM and Na...e.g.
There is significant multiple scattering and another backscattering peak (Fe-O) at 3.6Angstroms. All of these are going to spread underneath that peak in the FT. You might also be getting some interference from the 4.07A MS stuff. It doesn't seem a surprise that just including TM and Na is giving problems.
What is your high-R cutoff? Have you tried including multiple-scattering or that 4th backscattering contribution?
cheers, Robert
On 2024-01-09 12:06 a.m., Otal Eugenio wrote:
Dear all, Happy New Year! I am dealing with the fitting of NaMn0.3Fe0.4Ni0.3O2 second shell. I have Mn, Ni, and Fe at 2.9772Å and Na at 3.1859Å, showing only one shell. If I use any of the transition metals (dZ <5) for fitting the second coordination shell. fitting is fine, but when I introduce the Na path, the fitting has no sense, CN_Na grows and also its error. Even including Na, I have Nvary = 10 and Ninp = 13.98, so I am getting out of ideas and nothing helpful in the ifeffit Archive until now. Is there any strategy for dealing with mixed second coordination shells? I am attaching the file exported from Larch and the cif file. Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
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Hi Eugenio:
This looks like a layered structure, most likely a P2 or P3 phase. Is this
correct? How sure are you that you have a single phase and that the Na
ions are well ordered? Is it possible that there is so much disorder in
the M-Na distances that they wash out any contribution? In that case, the
second M-O distance would probably be more important. You also do not
mention if this is Ni, Fe or Mn edge data. Is it possible that these
differ?
Carlo
On Tue, Jan 16, 2024 at 11:30 PM Otal Eugenio
Dear Robert, Thanks for your detailed answer. I am cutting at R=3.35. I also tried to go up to 4.0 to provide more freedom and to include the SS TM-O at 3.6. It seems that including MS was not fruitful at the moment. I found the contribution very tiny, Importance < 10. I included the path at 3.6, and it fits well, but when I include the Na, the CN_Na goes to high values (>10) and errors (~+/- 50) I also tried to restrict the CN of TM to force the Na to take place and get good results. Also useless. I was checking the data in R_real and the TM and Na paths. I see the TM path is in phase while the Na path is not. I wonder if this is affecting the fit. How should I constrain the fitting to solve this situation? Best regards.
[image: image.png]
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
On Wed, Jan 17, 2024 at 1:24 AM Robert Gordon
wrote: Hi Otal,
I ran a quick FEFF simulation just to see what is present under that second peak in the FT. There are many more shells than just TM and Na...e.g.
There is significant multiple scattering and another backscattering peak (Fe-O) at 3.6Angstroms. All of these are going to spread underneath that peak in the FT. You might also be getting some interference from the 4.07A MS stuff. It doesn't seem a surprise that just including TM and Na is giving problems.
What is your high-R cutoff? Have you tried including multiple-scattering or that 4th backscattering contribution?
cheers, Robert
On 2024-01-09 12:06 a.m., Otal Eugenio wrote:
Dear all, Happy New Year! I am dealing with the fitting of NaMn0.3Fe0.4Ni0.3O2 second shell. I have Mn, Ni, and Fe at 2.9772Å and Na at 3.1859Å, showing only one shell. If I use any of the transition metals (dZ <5) for fitting the second coordination shell. fitting is fine, but when I introduce the Na path, the fitting has no sense, CN_Na grows and also its error. Even including Na, I have Nvary = 10 and Ninp = 13.98, so I am getting out of ideas and nothing helpful in the ifeffit Archive until now. Is there any strategy for dealing with mixed second coordination shells? I am attaching the file exported from Larch and the cif file. Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
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-- Carlo U. Segre (he/him) -- Duchossois Leadership Professor of Physics Professor of Materials Science & Engineering Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Phone: 312.567.3498 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org
Dear Carlo,
Thanks for your answer.
Yes, it is a layered material. I was measuring in situ the transformation
from O3 to P3.
I am not sure that Na atoms are ordered, it is a light element in a layered
structure and I applied some cycles to form the electrolyte-cathode
interphase, and disorder can be found there. I shook the structure a
little, your observation is correct.
I compared the spectra of a non-cycled one (blue) with a cycled one (red)
and the differences are minimal.
[image: image.png][image: image.png]
I was measuring all the edges, all showed the same problem, Na is
impossible to include in the fitting.
The goal was to monitor changes in the first coordination shell during the
battery operation. I found all the necessary information to understand the
system.
To fit the second coordination shell was attempted to evaluate the Na
concentration along the cycles and complement the electrochemical
measurements.
Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL
Assistant Professor
Dept. of Materials Chemistry
Shinshu University
4-17-1 Wakasato, Nagano 380-8553, JAPAN
eugenio_otal@shinshu-u.ac.jp
https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
On Wed, Jan 17, 2024 at 2:56 PM Carlo Segre
Hi Eugenio:
This looks like a layered structure, most likely a P2 or P3 phase. Is this correct? How sure are you that you have a single phase and that the Na ions are well ordered? Is it possible that there is so much disorder in the M-Na distances that they wash out any contribution? In that case, the second M-O distance would probably be more important. You also do not mention if this is Ni, Fe or Mn edge data. Is it possible that these differ?
Carlo
On Tue, Jan 16, 2024 at 11:30 PM Otal Eugenio < eugenio_otal@shinshu-u.ac.jp> wrote:
Dear Robert, Thanks for your detailed answer. I am cutting at R=3.35. I also tried to go up to 4.0 to provide more freedom and to include the SS TM-O at 3.6. It seems that including MS was not fruitful at the moment. I found the contribution very tiny, Importance < 10. I included the path at 3.6, and it fits well, but when I include the Na, the CN_Na goes to high values (>10) and errors (~+/- 50) I also tried to restrict the CN of TM to force the Na to take place and get good results. Also useless. I was checking the data in R_real and the TM and Na paths. I see the TM path is in phase while the Na path is not. I wonder if this is affecting the fit. How should I constrain the fitting to solve this situation? Best regards.
[image: image.png]
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
On Wed, Jan 17, 2024 at 1:24 AM Robert Gordon
wrote: Hi Otal,
I ran a quick FEFF simulation just to see what is present under that second peak in the FT. There are many more shells than just TM and Na...e.g.
There is significant multiple scattering and another backscattering peak (Fe-O) at 3.6Angstroms. All of these are going to spread underneath that peak in the FT. You might also be getting some interference from the 4.07A MS stuff. It doesn't seem a surprise that just including TM and Na is giving problems.
What is your high-R cutoff? Have you tried including multiple-scattering or that 4th backscattering contribution?
cheers, Robert
On 2024-01-09 12:06 a.m., Otal Eugenio wrote:
Dear all, Happy New Year! I am dealing with the fitting of NaMn0.3Fe0.4Ni0.3O2 second shell. I have Mn, Ni, and Fe at 2.9772Å and Na at 3.1859Å, showing only one shell. If I use any of the transition metals (dZ <5) for fitting the second coordination shell. fitting is fine, but when I introduce the Na path, the fitting has no sense, CN_Na grows and also its error. Even including Na, I have Nvary = 10 and Ninp = 13.98, so I am getting out of ideas and nothing helpful in the ifeffit Archive until now. Is there any strategy for dealing with mixed second coordination shells? I am attaching the file exported from Larch and the cif file. Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
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-- Carlo U. Segre (he/him) -- Duchossois Leadership Professor of Physics Professor of Materials Science & Engineering Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Phone: 312.567.3498 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org
HI Eugenio, Have you seen this work? I came across it last night. https://www.nature.com/articles/srep43791 "Local structures around the substituted elements in mixed layered oxides" They experienced a similar issue: "... In the O3 compound, we included the contribution from the first- (O), second- (/M/), and third- (Na) nearest neighbor elements. In the P2 compounds, we included the contributions from the first- (O), third- (/M/), and fifth- (O) nearest neighbor elements. We omitted the contribution from the second- (Na2) and fourth- (Na1) nearest neighbor elements because the occupancy (/g/ = 0.21–0.41) is small. In both cases, we fixed /N/_j for the three elements at the crystallographic value (=6)..." "...We found that the R values of the third paths, /i.e/. the /M/–Na distances in the O3 compounds and the longer /M/ - O distances of the P2 compounds, are seriously deviated from the crystallographic values. In addition, the/σ/_j ^2 values for these paths are significantly large (~0.01–0.03 Å^2 ) as compared with those of the first and second paths. In this sense, the EXAFS analysis model including the third paths remains ambiguous. We performed another EXAFS analysis with omitting the third path to validate the discussion above. We observed the same trend of the /M/ – O and /M/ – /M/ distances between the compounds even if we omitted the third path...." Disorder does seem to be an issue. Do you have a pure phase result to which you can compare i.e. unaltered or non-substituted? cheers, -R. On 2024-01-16 11:40 p.m., Otal Eugenio wrote:
Dear Carlo, Thanks for your answer. Yes, it is a layered material. I was measuring in situ the transformation from O3 to P3. I am not sure that Na atoms are ordered, it is a light element in a layered structure and I applied some cycles to form the electrolyte-cathode interphase, and disorder can be found there. I shook the structure a little, your observation is correct. I compared the spectra of a non-cycled one (blue) with a cycled one (red) and the differences are minimal. image.pngimage.png I was measuring all the edges, all showed the same problem, Na is impossible to include in the fitting. The goal was to monitor changes in the first coordination shell during the battery operation. I found all the necessary information to understand the system. To fit the second coordination shell was attempted to evaluate the Na concentration along the cycles and complement the electrochemical measurements. Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp mailto:eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
On Wed, Jan 17, 2024 at 2:56 PM Carlo Segre
wrote: Hi Eugenio:
This looks like a layered structure, most likely a P2 or P3 phase. Is this correct? How sure are you that you have a single phase and that the Na ions are well ordered? Is it possible that there is so much disorder in the M-Na distances that they wash out any contribution? In that case, the second M-O distance would probably be more important. You also do not mention if this is Ni, Fe or Mn edge data. Is it possible that these differ?
Carlo
On Tue, Jan 16, 2024 at 11:30 PM Otal Eugenio
wrote: Dear Robert, Thanks for your detailed answer. I am cutting at R=3.35. I also tried to go up to 4.0 to provide more freedom and to include the SS TM-O at 3.6. It seems that including MS was not fruitful at the moment. I found the contribution very tiny, Importance < 10. I included the path at 3.6, and it fits well, but when I include the Na, the CN_Na goes to high values (>10) and errors (~+/- 50) I also tried to restrict the CN of TM to force the Na to take place and get good results. Also useless. I was checking the data in R_real and the TM and Na paths. I see the TM path is in phase while the Na path is not. I wonder if this is affecting the fit. How should I constrain the fitting to solve this situation? Best regards.
image.png
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp mailto:eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
On Wed, Jan 17, 2024 at 1:24 AM Robert Gordon
wrote: Hi Otal,
I ran a quick FEFF simulation just to see what is present under that second peak in the FT. There are many more shells than just TM and Na...e.g.
There is significant multiple scattering and another backscattering peak (Fe-O) at 3.6Angstroms. All of these are going to spread underneath that peak in the FT. You might also be getting some interference from the 4.07A MS stuff. It doesn't seem a surprise that just including TM and Na is giving problems.
What is your high-R cutoff? Have you tried including multiple-scattering or that 4th backscattering contribution?
cheers, Robert
On 2024-01-09 12:06 a.m., Otal Eugenio wrote:
Dear all, Happy New Year! I am dealing with the fitting of NaMn0.3Fe0.4Ni0.3O2 second shell. I have Mn, Ni, and Fe at 2.9772Å and Na at 3.1859Å, showing only one shell. If I use any of the transition metals (dZ <5) for fitting the second coordination shell. fitting is fine, but when I introduce the Na path, the fitting has no sense, CN_Na grows and also its error. Even including Na, I have Nvary = 10 and Ninp = 13.98, so I am getting out of ideas and nothing helpful in the ifeffit Archive until now. Is there any strategy for dealing with mixed second coordination shells? I am attaching the file exported from Larch and the cif file. Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp mailto:eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
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-- Carlo U. Segre (he/him) -- Duchossois Leadership Professor of Physics Professor of Materials Science & Engineering Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Phone: 312.567.3498 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org
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As Robert notes, it is likely that you have a lot of disorder in the Na
sites, particularly if there is also a P3 to O3 transition happening. If
the second shell fits using just the metal and oxygen atoms are reasonable,
then I would simply not worry about the Na and make the case that the
disorder washed out their contribution. More importantly, I would focus on
the bond lengths of the atoms you can see to detect a structural transition
although it will be very difficult as the transition typically consists of
the layers sliding against one another without changing the bond
lengths internal to the layers very much. If you want to discuss this more
off the list I am happy to do so.
Carlo
On Wed, Jan 17, 2024 at 1:41 AM Otal Eugenio
Dear Carlo, Thanks for your answer. Yes, it is a layered material. I was measuring in situ the transformation from O3 to P3. I am not sure that Na atoms are ordered, it is a light element in a layered structure and I applied some cycles to form the electrolyte-cathode interphase, and disorder can be found there. I shook the structure a little, your observation is correct. I compared the spectra of a non-cycled one (blue) with a cycled one (red) and the differences are minimal. [image: image.png][image: image.png] I was measuring all the edges, all showed the same problem, Na is impossible to include in the fitting. The goal was to monitor changes in the first coordination shell during the battery operation. I found all the necessary information to understand the system. To fit the second coordination shell was attempted to evaluate the Na concentration along the cycles and complement the electrochemical measurements. Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
On Wed, Jan 17, 2024 at 2:56 PM Carlo Segre
wrote: Hi Eugenio:
This looks like a layered structure, most likely a P2 or P3 phase. Is this correct? How sure are you that you have a single phase and that the Na ions are well ordered? Is it possible that there is so much disorder in the M-Na distances that they wash out any contribution? In that case, the second M-O distance would probably be more important. You also do not mention if this is Ni, Fe or Mn edge data. Is it possible that these differ?
Carlo
On Tue, Jan 16, 2024 at 11:30 PM Otal Eugenio < eugenio_otal@shinshu-u.ac.jp> wrote:
Dear Robert, Thanks for your detailed answer. I am cutting at R=3.35. I also tried to go up to 4.0 to provide more freedom and to include the SS TM-O at 3.6. It seems that including MS was not fruitful at the moment. I found the contribution very tiny, Importance < 10. I included the path at 3.6, and it fits well, but when I include the Na, the CN_Na goes to high values (>10) and errors (~+/- 50) I also tried to restrict the CN of TM to force the Na to take place and get good results. Also useless. I was checking the data in R_real and the TM and Na paths. I see the TM path is in phase while the Na path is not. I wonder if this is affecting the fit. How should I constrain the fitting to solve this situation? Best regards.
[image: image.png]
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Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
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On Wed, Jan 17, 2024 at 1:24 AM Robert Gordon
wrote: Hi Otal,
I ran a quick FEFF simulation just to see what is present under that second peak in the FT. There are many more shells than just TM and Na...e.g.
There is significant multiple scattering and another backscattering peak (Fe-O) at 3.6Angstroms. All of these are going to spread underneath that peak in the FT. You might also be getting some interference from the 4.07A MS stuff. It doesn't seem a surprise that just including TM and Na is giving problems.
What is your high-R cutoff? Have you tried including multiple-scattering or that 4th backscattering contribution?
cheers, Robert
On 2024-01-09 12:06 a.m., Otal Eugenio wrote:
Dear all, Happy New Year! I am dealing with the fitting of NaMn0.3Fe0.4Ni0.3O2 second shell. I have Mn, Ni, and Fe at 2.9772Å and Na at 3.1859Å, showing only one shell. If I use any of the transition metals (dZ <5) for fitting the second coordination shell. fitting is fine, but when I introduce the Na path, the fitting has no sense, CN_Na grows and also its error. Even including Na, I have Nvary = 10 and Ninp = 13.98, so I am getting out of ideas and nothing helpful in the ifeffit Archive until now. Is there any strategy for dealing with mixed second coordination shells? I am attaching the file exported from Larch and the cif file. Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
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-- Carlo U. Segre (he/him) -- Duchossois Leadership Professor of Physics Professor of Materials Science & Engineering Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Phone: 312.567.3498 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org
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-- Carlo U. Segre (he/him) -- Duchossois Leadership Professor of Physics Professor of Materials Science & Engineering Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Phone: 312.567.3498 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org
Dear Robert, Dear Carlo,
Thank you for sharing your knowledge.
I have scheduled beamline time next month, during which I can measure
samples prepared under various conditions; this might prove helpful.
Additionally, I have requested a cryostat for other measurements. I plan to
measure FMN at low temperatures as well, in the hope of detecting some
signal for sodium.
Once again, thank you!
Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL
Assistant Professor
Dept. of Materials Chemistry
Shinshu University
4-17-1 Wakasato, Nagano 380-8553, JAPAN
eugenio_otal@shinshu-u.ac.jp
https://sites.google.com/view/zettsu-laboratory/news-updates
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On Thu, Jan 18, 2024 at 6:26 AM Carlo Segre
As Robert notes, it is likely that you have a lot of disorder in the Na sites, particularly if there is also a P3 to O3 transition happening. If the second shell fits using just the metal and oxygen atoms are reasonable, then I would simply not worry about the Na and make the case that the disorder washed out their contribution. More importantly, I would focus on the bond lengths of the atoms you can see to detect a structural transition although it will be very difficult as the transition typically consists of the layers sliding against one another without changing the bond lengths internal to the layers very much. If you want to discuss this more off the list I am happy to do so.
Carlo
On Wed, Jan 17, 2024 at 1:41 AM Otal Eugenio
wrote: Dear Carlo, Thanks for your answer. Yes, it is a layered material. I was measuring in situ the transformation from O3 to P3. I am not sure that Na atoms are ordered, it is a light element in a layered structure and I applied some cycles to form the electrolyte-cathode interphase, and disorder can be found there. I shook the structure a little, your observation is correct. I compared the spectra of a non-cycled one (blue) with a cycled one (red) and the differences are minimal. [image: image.png][image: image.png] I was measuring all the edges, all showed the same problem, Na is impossible to include in the fitting. The goal was to monitor changes in the first coordination shell during the battery operation. I found all the necessary information to understand the system. To fit the second coordination shell was attempted to evaluate the Na concentration along the cycles and complement the electrochemical measurements. Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
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Who is John Galt?
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On Wed, Jan 17, 2024 at 2:56 PM Carlo Segre
wrote: Hi Eugenio:
This looks like a layered structure, most likely a P2 or P3 phase. Is this correct? How sure are you that you have a single phase and that the Na ions are well ordered? Is it possible that there is so much disorder in the M-Na distances that they wash out any contribution? In that case, the second M-O distance would probably be more important. You also do not mention if this is Ni, Fe or Mn edge data. Is it possible that these differ?
Carlo
On Tue, Jan 16, 2024 at 11:30 PM Otal Eugenio < eugenio_otal@shinshu-u.ac.jp> wrote:
Dear Robert, Thanks for your detailed answer. I am cutting at R=3.35. I also tried to go up to 4.0 to provide more freedom and to include the SS TM-O at 3.6. It seems that including MS was not fruitful at the moment. I found the contribution very tiny, Importance < 10. I included the path at 3.6, and it fits well, but when I include the Na, the CN_Na goes to high values (>10) and errors (~+/- 50) I also tried to restrict the CN of TM to force the Na to take place and get good results. Also useless. I was checking the data in R_real and the TM and Na paths. I see the TM path is in phase while the Na path is not. I wonder if this is affecting the fit. How should I constrain the fitting to solve this situation? Best regards.
[image: image.png]
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
On Wed, Jan 17, 2024 at 1:24 AM Robert Gordon
wrote: Hi Otal,
I ran a quick FEFF simulation just to see what is present under that second peak in the FT. There are many more shells than just TM and Na...e.g.
There is significant multiple scattering and another backscattering peak (Fe-O) at 3.6Angstroms. All of these are going to spread underneath that peak in the FT. You might also be getting some interference from the 4.07A MS stuff. It doesn't seem a surprise that just including TM and Na is giving problems.
What is your high-R cutoff? Have you tried including multiple-scattering or that 4th backscattering contribution?
cheers, Robert
On 2024-01-09 12:06 a.m., Otal Eugenio wrote:
Dear all, Happy New Year! I am dealing with the fitting of NaMn0.3Fe0.4Ni0.3O2 second shell. I have Mn, Ni, and Fe at 2.9772Å and Na at 3.1859Å, showing only one shell. If I use any of the transition metals (dZ <5) for fitting the second coordination shell. fitting is fine, but when I introduce the Na path, the fitting has no sense, CN_Na grows and also its error. Even including Na, I have Nvary = 10 and Ninp = 13.98, so I am getting out of ideas and nothing helpful in the ifeffit Archive until now. Is there any strategy for dealing with mixed second coordination shells? I am attaching the file exported from Larch and the cif file. Best regards.
(^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=)
Eugenio H. OTAL Assistant Professor Dept. of Materials Chemistry Shinshu University 4-17-1 Wakasato, Nagano 380-8553, JAPAN eugenio_otal@shinshu-u.ac.jp https://sites.google.com/view/zettsu-laboratory/news-updates
¯\_(ツ)_/¯¯\_(ツ)_/¯
Who is John Galt?
¯\_(ツ)_/¯¯\_(ツ)_/¯
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-- Carlo U. Segre (he/him) -- Duchossois Leadership Professor of Physics Professor of Materials Science & Engineering Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Phone: 312.567.3498 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org
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-- Carlo U. Segre (he/him) -- Duchossois Leadership Professor of Physics Professor of Materials Science & Engineering Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Phone: 312.567.3498 segre@iit.edu http://phys.iit.edu/~segre segre@debian.org
participants (4)
-
Carlo Segre
-
Otal Eugenio
-
Robert Gordon
-
Robert Gordon