The influence of charge compensation defects on the spectroscopic properties of europium doped Ca9Y( PO4)(7)

摘要

In this study, a series of Ca9Y(PO4)(7) compounds doped with 5% of Eu ions and with different [Y]/[Ca] ratios was synthesized using the Pechini method. Due to the presence of two different cations in the studied matrix (Ca2+ and Y3+) that are available for europium substitution, the synthesis parameters were selected to obtain the incorporation of the europium ions (5% mol) into the calcium sites only. The phase composition as well as elemental analysis and the spectroscopic measurements, carried out before and/or after the reduction of Eu3+ were performed to characterize the obtained phosphors. The XRD patterns show that in all cases the obtained materials consist of pure phase of Ca9Y(PO4)(7). PLE and PL spectra measured before the reduction indicate that for the materials with the excess of yttrium, an additional Eu3+ site is observed which was not observed for materials with a deficiency of yttrium. For samples obtained after the reduction, the luminescence of Eu2+ depends on the changes of the Y/Ca ratio. The observed differences in Eu2+ luminescence are discussed taking into account the creation of different compensation defects depending on change of the Y/Ca ratio.