X-ray photoelectron spectroscopy and NIR self-quenching emission behavior in Ho3+ doped YOF and V-YOF

Abstract

Stoichiometric (YOF) and non-stoichiometric yttrium oxyfluoride (Y7O6F9) also known as the vernier phase (V-YOF) were investigated for possible optical applications. Both structures were prepared from a single source through the pyrolysis method. The V-YOF and YOF structures decomposed at 900 °C and 950 °C, respectively. X-ray photoelectron spectroscopy revealed four different yttrium sites in the V-YOF structure. The visible holmium ions emission doped in both consisted of three regions due to the 5S2,5F4 → 5I8, 5F5 → 5I8, and 5S2,5F4 → 5I7 transitions. The YOF structure's visible lifetime was also longer than in the V-YOF structure. The near-infrared photoluminescence emission originated from 5S2,5F4 → 5I6, 5I6 → 5I8 in both structures. The 5S2,5F4 → 5I6 near-infrared lifetimes for both decreased, indicating an energy transfer process. The 5I6 → 5I8 lifetime in both fluctuated due to the possibility of self-quenching through photon-trapping processes. The lifetimes were in the microseconds range.