The Role of Er3+ Content in the Luminescence Properties of Y3Al5O12 Single Crystals: Incorporation into the Lattice and Defect State Creation

Erbium-doped Y3Al5O12 (YAG) single crystals grown using the micro-pulling-down technique were investigated. Three Er concentrations were chosen: 0.1, 0.3 and 1 at%. Er3+ electron paramagnetic resonance (EPR) spectra were measured in the ground and first excited states. The corresponding g tensors and Er-167 hyperfine interaction were changing upon Er content indicating moderation of the Er-O bond length and/or Er local surrounding. Photoluminescence (PL) and radioluminescence (RL) spectra were complex, consisting of strongly overlapped typical Er3+ transitions. In addition, there were other broad PL band (3.1 eV) and RL band (3.95 eV) attributed to the F+ center and yttrium substituting for aluminum (Y-Al), respectively. The X-ray excited decay kinetics exhibited a decrease of the decay time of the Y-Al from hundreds of nanoseconds to nanoseconds upon Er doping level. This is discussed and explained considering EPR data.