Investigation of Luminescence and Photoacoustic Properties in Ce3+-Doped Ln3Al5O12 (Ln = Lu, Y, Gd) Garnet

Optical and photoacoustic properties of Ce3+-doped lanthanide (Lu, Y, Gd) aluminum garnet were investigated. In the photoacoustic (PA) spectra, the 5d(1) (lowest 5d level) band of Ce3+ was observed at around 450 nm in the obtained Ce3+-doped garnet samples. This result shows that a part of the excited energy is converted to thermal energy, which is generated by some nonradiative processes. In Y3Al5O12:Ce3+, the 5d(1) PA peak wavelength is shorter than the 5d(1) photoluminescence excitation peak wavelength, which indicates that part of the heat generation is caused by the phonon relaxation process within 5d(1) state. The PA intensity and luminescence quantum efficiency of the Ce3+-doped gadolinium yttrium aluminum garnets ((Gd0.5Y0.5)(3)Al5O12, (Gd0.75Y0.25)(3)Al5O12) are much stronger and smaller, respectively, than those of Y3Al5O12:Ce3+. Based on these results and the persistent luminescence excitation spectra, we conclude that (Gd0.5Y0.5)(3)Al5O12:Ce3+ and (Gd0.75Y0.25)(3)Al5O12:Ce3+ possess the additional heat generation process explained by the thermal ionization. (C) The Author(s) 2016. Published by ECS. All rights reserved.