Dear scientists,
Could anyone explain the effect of crystallite size (decreasing to reach few nanometers scale) of inorganic phosphor materials on the line-shape of the emission bands (splitting, broadening) including the decrease or increase of emission intensities and also crystal symmetry effects on the degeneracy of energy levels ?
Thanks for your contribution
Ilyes.
The emission spec spectra depends on energy band structure of the material.
It is so as the crystal size decreases the bandgap increases and so the spectrum will be shifted to lower wavelength.
The other effect is that because of the large surface states in the energy gap , there will be some broadening of line widths. Also, because of the random size pf the grains one expects much wider spectrum with lower intensity compared to the mono crystalline one.
Best wishes
Dear Lyes,
As pointed out before, the line width will broaden with decreasing particle size. This effect is well known for RE3+ doped phosphors. Please read the excellent review by Prof. Koen Binnemans on the interpretation of spectra of Eu3+ phosphors:
Coordination Chemistry Reviews 295 (2015) 1–45
All the best,
Thomas
Dear Zekry
The shift occurs when RE3+ ions occupied or substitute materials which resulted in Blue and Red-Shift on Emission Spectra.
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