X-ray diffraction in the presence of electric potential

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Discussion Overview

The discussion revolves around the effects of external electric potential on X-ray diffraction (XRD) patterns of a material, particularly in the context of a battery material during discharging. Participants explore the implications of observed differences in XRD patterns between cases with and without electric potential, considering the role of electron distribution and specific material properties.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that the presence of electric potential appears to change the electron distribution in the material, suggesting a possible interaction with light-sensitive properties due to the presence of Ti4+ with empty 3d orbitals.
  • Another participant questions the nature of the external fields involved, indicating that significant perturbation of molecular wavefunctions and interatomic bonds would be expected only with sufficiently large fields.
  • A piezoelectric effect is proposed as a potential cause for the observed differences in XRD patterns, although it is suggested that this effect would need to be substantial.
  • Further clarification reveals that the discussion pertains to in situ synchrotron XRD during battery discharging, where expected phase transitions were not observed during discharging but occurred after stopping the circuit.
  • One participant expresses skepticism about the significance of the external potential, stating that the observed effects are peculiar to the material in question and not seen in others.

Areas of Agreement / Disagreement

Participants express differing views on the significance and implications of the external electric potential, with no consensus reached on whether the observed effects are substantial or merely artifacts of the experimental conditions.

Contextual Notes

Participants note the potential limitations of their assumptions regarding the strength of the electric potential and its effects on molecular interactions, as well as the specific characteristics of the material being studied.

bearcharge
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Hi, I was conducting an experiment on a material using XRD and I investigated two cases. One case is the presence of outside electric potential, that is, the material being connected to a electric circuit. The other case is the absence of this electric potential. I found that the two XRD patterns from these two cases differ, though not significantly. I think this is suggesting that the exerted electric potential is changing the original electron distribution, which is not surprising, right? Considering that the sample contains Ti4+ which has empty 3d orbitals, does this fact possibly has relationship to what I observed? Yes, I think I'm implying the interaction of X-ray with possible light-sensitive material in the presence of an electric potential. I'm sorry if this question belongs more to the chemistry area :) Thanks!
 
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What sort of external fields are we talking about here? I'm not familiar with such an effect, which doesn't mean it isn't commonly known to others, but I would expect it if the fields are large enough to perturb molecular wavefunctions and therefore interatomic bonds. You see analogous effects with isolated atoms, Stark line broadening and shifts.
 
A piezoelectric effect could also cause this, but it'd have to be a big effect, I think.
 
JeffKoch said:
What sort of external fields are we talking about here? I'm not familiar with such an effect, which doesn't mean it isn't commonly known to others, but I would expect it if the fields are large enough to perturb molecular wavefunctions and therefore interatomic bonds. You see analogous effects with isolated atoms, Stark line broadening and shifts.

Thanks for the answer. Actually, I was talking about an in situ synchrotron XRD of a battery material during discharging. During discharging, a two-phase transition was expected. However, this was not observed when the discharging was going on. Instead, the phase changed can be observed when I stopped the discharging circuit and then radiated the X-ray beam. I wonder if external electric potential is playing a role in this even though this potential is as small as several Vs...
 
fleem said:
A piezoelectric effect could also cause this, but it'd have to be a big effect, I think.

Thank you for the suggestion! As I explained in the previous reply, the external potential is only several Vs. I assume this is far from being big... The experiment result is peculiar as it didn't happen for other materials but for this one which has a Ti4+ in it. I was wondering if this is something special...
 

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