Fabrication and luminescence properties of U:YAG transparent ceramic

Uranium doped yttrium aluminum garnet (YAG) transparent ceramic with Ca2+ as charge compensator and sintering aid was firstly fabricated by vacuum sintering technique using the co-precipitation synthesis of raw powders. The structural, optical spectral and luminescence properties of the U:YAG ceramic have been investigated in detail. The experimental results show that uranium doped in YAG matrix has not changed the crystal structure. Vacuum sintering 15 h in 1800 °C, the sample has a pore-free structure with an average grain size of about 3.5 μm, and in-line transmittance reaches up to 78% in the visible wavelength region. The excitation spectrum showed a sharp band around 458 nm, and the emission spectrum revealed the intense green emission located at 520 nm. Further, with respect to the shape of emission band and luminescence color, uranium was inferred to exist as uranate ion (UO66−) in the YAG host where it replaces the 'Y' ions at dodecahedral site with surrounding defect centers created for charge compensation.