Luminescence properties of CsI:Eu crystals

The work is aimed to research of CsI:Eu single crystals’ luminescence at different excitations in the wide temperature range (from 8 to 300 K) and admixture concentration from 10−4% up to 10−1% of Eu2+ ions. This study was directed to separation of different luminescence mechanisms and luminescence quenching explore. It is found that due to the temperature quenching the room temperature yield is decreased in order of magnitude even for heavy Eu doped CsI crystals. Intense low temperature luminescence band at 441–448 nm connected with Eu2+ 4f6 5d → 4f7 radiative transition is observed. The results obtained show that the excitonic mechanism plays the main role in energy transfer process to Eu2+ ions and this is the reason for relatively low light yield of this emission at RT. The nature of the additional emission bands (410, 450, 480 and 500 nm) are apparently caused by the significant non-isomorphism of cations and/or by the presence of oxygen-containing admixtures.

► The optical and luminescence properties of CsI:Eu crystals has been studied.
► Intense low temperature luminescence band at 441 nm in CsI:Eu is observed.
► The temperature evolution of emission bands shows the change of the main mechanism.
► Excitonic mechanism plays the main role in energy transfer process in CsI:Eu.