NaLaF4:Er3+ up-conversion spectrum in glass an ceramics

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Discussion Overview

The discussion centers on the differences observed in the up-conversion spectrum of NaLaF4:Er3+ in glass versus ceramics, specifically focusing on luminescence band width, intensity variations, and potential underlying mechanisms such as phonon energy and the Stark effect.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that the luminescence bands in glass are wider due to the lattice structure allowing for more non-equivalent sites for ions, which affects the electric fields around the ions.
  • Another participant suggests that the shift in bands observed in glass could be due to the disturbance of symmetry in the crystal structure, affecting selection rules for absorption and emission lines.
  • A participant mentions that the intensity of luminescence is higher in ceramics, attributing this to lower phonon energy in ceramics compared to glass, although the exact mechanism of how phonon energy affects intensity remains unclear.
  • One participant proposes that the widening and shift of bands could be explained by the Stark effect, but expresses uncertainty regarding the intensity issue.
  • Another participant suggests obtaining spectra at low temperatures to minimize phonon effects, although they acknowledge that this may not be feasible.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms behind the observed spectral differences, particularly regarding the intensity of luminescence and the role of phonon energy. The discussion remains unresolved with multiple competing explanations presented.

Contextual Notes

Participants acknowledge limitations in their current understanding, particularly regarding the mathematical explanations for the intensity differences and the impact of phonon energy on luminescence.

prehisto
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Hi,Guys.
I have registered 2 spectrum's. 980nm induced spectrum of NaLaF4:Er3+ glass and NaLaF4:Er3+ ceramics.
Now, i have to explain the observed differences.

spctr.jpg


So the first one and obvious one,is that in the case of glass, luminescence bands becomes wider,because of the lattice structure of glass. Glass has more possible no-equivalent structure spots where ions can build into therefore having different electrical fields,which affect the levels of ions.

But there seemingly is another effect ,shift of the bands. Could someone can,please,explain me is it possible and if yes, why this could happen ?

There is another effect , in the case of ceramics , the intensity is much higher . I have red that that s related to phonon energy. Glass has high phonon energy,cceramics-low. But how the energy of phonos affect the intensity of luminescence is unclear for me.

p.s. this is part of my study semester ,laboratory work.
 
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Width is wider, intensity is lower. And vice versa.
Integral is approximately the same.
Try to get spectra at low temperature (liquid N2) - without phonons.
 
Just a guess: In the crystal the Erbium impurities occupy some positions of high symmetry which lead to some selection rules on the absorption and emission lines. In a glass, this symmetry is disturbed and the selection rules are weakened which can lead to a shift of line strength from one transition to another.
 
ycheff said:
Width is wider, intensity is lower. And vice versa.
Integral is approximately the same.
Try to get spectra at low temperature (liquid N2) - without phonons.

I do not think it is possible to explain it just mathematically.
Yes,the low temperature spectra would definitely help, but unfortunately its not possible.

Ok, i think the widening and the shift could be explained by Stark effect.
But the intensity problem still is unclear.
 

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