Vanadium in yttrium aluminum garnet: Charge states and localization in the lattice

Abstract

Vanadium ions charge states and their incorporation in the yttrium aluminum garnet Y 3 Al 5 O 12 (YAG) lattice were studied by the correlated optical absorption and electron paramagnetic resonance (EPR) measurements. In as-grown crystals, the occupation of the V 3+ at both the octahedral and tetrahedral aluminum sites was proven. The V 3+ to V 4+ charge transformation was observed after annealing in air, whereas annealing in the hydrogen atmosphere resulted exclusively in a slight weakening of the V 3+ absorption bands due to partial recharge of these ions. Spin Hamiltonian parameters of the V 3+ and V 4+ ions at the tetrahedral sites including the zero field splitting and the 51 V hyperfine constants have been determined using the high-frequency, up to 300 GHz, EPR measurements. From the analysis of the spin Hamiltonian parameters in the framework of the crystal field theory, the ground state energy levels splitting of the V 3+ and V 4+ ions were calculated. The charge distribution over the tetrahedral V 3+ and its nearest oxygen surroundings was found to be strongly inhomogeneous whereas the tetrahedral V 4+ ion concentrated the charge with very weak participation of surrounding ligands. Furthermore, the correlation of the optical and EPR data allowed the proper assignment of the optical absorption peaks in YAG:V crystals.

Rare-earth ions incorporation into Lu2Si2O7 scintillator crystals: Electron paramagnetic resonance and luminescence study

“…It is in the 0.93 -0.98 cm -1 range. This value also agrees with the tetrahedral position of the V 3+ ions [31,33]. It means that this impurity ion substitutes for Si 4+ .…”

“…The corresponding g factor is thus not smaller than approximately 3.05. This is completely inconsistent with the V 4+ (3d 1 ion) exhibiting g factor values less than 2 (see e.g., very recent investigation of the vanadium ion charge states by EPR in Y3Al5O12 [33]). Therefore, this rather points out large zero field splitting (ZFS) constant of this d 2 ion, greater than the microwave quantum used in the X band EPR measurements.…”

Synthesis-enabled exploration of chiral and polar multivalent quaternary sulfides

“…In the case of V, the EPR spectrum at 6 K did not have adequate signal-to-noise ratio for a proper assignment. 90,91 …”

“…shows that Ti has 3+ oxidation states while its neighbors in group 4 (Zr and Hf) have 4+ oxidation states (Table S1B and S4). In the case of V, the EPR spectrum at 6 K did not have adequate signalto-noise ratio for a proper assignment 90,91 .…”

Li+ incorporation and defect-creation processes imposed by X-ray and UV irradiation in Li-codoped Y3Al5O12:Ce scintillation crystals

“…This research is a continuation of our study on electron and hole trapping in wide bandgap oxide scintillation materials, where the dominant trapping sites are oxygen vacancies, antisite ions, and lattice oxygen ions, 16,17 using combinations of the local probe EPR method with optical characterization. It is clear that the chemistry and efficiency of the trapping processes substantially depend on the codoping of the crystals.…”