Upconversion luminescence and kinetics in Er:YAlO3 under 652.2 nm excitation

Ultraviolet and visible upconversion properties of Er³⁺ in YAlO₃ were investigated following 652.2 nm excitation of the multiples ⁴F_9/2. The luminescence and excitation spectra were recorded. Ultraviolet (326-342 and 354-359 nm), violet (405-420 nm), blue (436-442 nm) and green (525-575 nm) upconversion and infrared downconversion luminescence were simultaneously observed. The intense green luminescence corresponds to the emissions from the thermal coupled ⁴S_3/2 and ²H_11/2 bands and ²G_9/2 level. Energy transfer upconversion processes were proposed to explain the upconversion phenomena. The luminescence kinetics was discussed in detail by the analyses of fluorescence decay curves.