Emission from the high lying excited states of Ho3+ ions in YAP and YAG crystals

Temperature and concentration quenching of Tb3+ emissions in Y4Al2O9 crystals

“…Assuming that 5 D 3 level splitting in YAM is similar, it is indeed possible that the obtained E of about 2 cm −1 could be involved in creating thermal population of second Stark level of 5 D 3 level. Similar tendency at low temperature was registered for Ho 3+ 3 D 3 decay in YAP [34] whereas in YAG it was much less noticeable. Such dependence on the host matrix may imply that the fast decrease of decay time at low temperature is related to crystal field, which has strong impact not only on the energy level positions, but also on their Stark splitting.…”

Ultraviolet and violet upconversion luminescence in Ho3+-doped Y2O3 ceramic induced by 532-nm CW laser

“…Five emission bands centered at 306, 362, 390, 412 and 428 nm were generated by intra-4f electron transitions of Ho 3+ ions. Emissions around 306, 362, and 412 nm can be assigned to the transitions from 3 D 3 state to the ground state 5 I 8 and the first two excited states 5 I 7 and 5 I 6 , respectively, corresponding well to the fluorescence emissions excited by the 288 nm pumping light [9]. Peaks centered at 390 and 428 nm can be assigned to the transitions 5 G 4 → 5 I 8 and 5 G 5 → 5 I 8 of the Ho 3+ ions [5].…”

“…There are also several high-lying metastable levels that can give rise to transitions at various wavelengths in the visible and UV regions [9]. Most upconversion studies on Ho 3+ -doped materials were mainly focused on infrared and visible regions.…”

A novel green phosphor LaMgAl11O19:Ho3+ for near-UV/blue light-pumped white light-emitting diodes

“…The intensities then decreased as Ho 3+ concentration increased further due to the concentration quenching. The concentration quenching was due to the crossrelaxation (CR) processes between the Ho 3+ ions, through the possible CR channels such as 5 S 2 → 5 I 4 = 5 I 8 → 5 I 7 [16]. The mechanisms of CR processes are based on the electric multipole interactions including dipole-dipole (d-d), dipole-quadrupole (d-q) and quadrupole-quadrupole (q-q) interactions.…”