Abstract
The luminescence of Eu 2+ in (Ca,Sr), MgSiO 2O 7, MSiO 4 (M, Ba, Sr, Ca). BaSi 2O 7, BaMgSiO 4, CaMgSiO 4 and Sr 2LiSiO 4F has been studied. In these structures there are chains of alkaline earth ions. In some cases the Eu 2+ ion in these chains shows emission at long wavelengths. This effect is due to preferential orientation of a d orbital and lifts a model proposed earlier. In (Ca,Sr) 2MgSi 2O 7Eu 2+, it is shown that when the cell parameters are increased by replacing (part of) the calcium by strontium ions, the effect of preferential orientation of a d orbital in the chain direction decreases and the Eu 2+ emission shifts to shorter wavelengths. However, in SrSiO 4Eu 2+ the chains of alkaline earth ions are close together and a blue E 2+ emission is observed. This indicates that preferential orientation of only d orbital is required to obtain a Eu 2+ emission at low energies.
Published Version
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