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

[prehisto]

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.

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.

 

[ycheff]

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.

 

[DrDu]

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.

 

[prehisto]

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.