Thermal stability and annealing behavior of photoluminescence from Eu doped YAG

• Thermal stability and annealing of Eu doped YAG are evaluated by PL spectra.
• Color of Eu doped YAG varies with O2 concentration and annealing.
• PL at 590, 607, 624, 647 and 709 nm from Eu3+ are observed from Eu doped YAG.
• Temperature dependence of PL is improved by annealing.
• Oxidation of Eu2+ is responsible for de-coloration and temperature dependence of PL.

Eu2O3 doped Y3Al5O12 (YAG) crystals have been grown using a floating zone technique and evaluated thermal stability and annealing behavior of PL for a fluorescence thermo-sensor application. Color of the crystals grown varies from deep purple to colorless with O2 concentration of the growth atmosphere and annealing in air. Photoluminescence (PL) peaking at λ = 590, 607, 624, 647 and 709 nm due to Eu3+ ions are observed from the crystals under UV excitation. Anomalous temperature dependence of PL intensity, which is observed in as-grown crystals, is improved greatly by annealing through the heat cycle. From annealing behavior of optical absorption spectra, residual Eu2+ ions are suggested to be responsible for the de-coloration and the improvement of anomalous temperature dependence of Eu doped YAG crystals.