X-ray Excited Luminescence from Cr Doped YAG Crystals

X-ray excited visible light luminescence were evaluated from Cr doped Y 3 Al 5 O 12 (YAG) crystals using an X-ray powder diffractometer adapting a fiber spectrometer, a digital camera, and a LED illumination. Red colored luminescence peaking at λ = 678, 690, 708, and 726 nm were observed from Cr doped YAG under irradiation by both CuK α X-ray and a violet LED ( λ = 405 nm). Peak wavelengths of X-ray excited luminescence are the same as those of photoluminescence (PL). The peak intensities of X-ray excited luminescence, which increases linearly with X-ray strength, increases up to Cr concentration at around 0.5 mol%, then decreases gradually with Cr concentration due to a concentration quenching. It was found that the concentration quenching of X-ray excited luminescence occurs at a lower concentration at around 0.5 mol% than that of PL at around 3.5 mol%.