Fabrication of transparent Ce:LuAG ceramics by a solid-state reaction method

Lu₂O₃ powders with an average particle size of about 40 nm were produced by a precipitation method using Lu (NO₃)₃ and NH₄HCO₃ as starting materials. The precipitation precursor is amorphous and transforms into pure Lu₂O₃ phase by calcining at 600°C for 2 h. The resultant Lu₂O₃, Al₂O₃ and CeO₂ powders were mixed by ball milling, and then sintered into a fully transparent Ce:LuAG ceramic body by vacuum sintering at 1760°C for 10 h and annealed at 1450°C for 20 h. The resultant transparent ceramic has a uniform microstructure with an average grain size of about 4 μm. The polished Ce:LuAG ceramic disk with 1.2 mm thickness is highly transparent. The transmittance in the visible region reaches 56%, which is 72% of the theoretical value. The emission spectrum at 470-650 nm with the double peak structure (517 nm and 552 nm) excited by X-ray is the characteristic spectrum of Ce³⁺ due to the 5d-4f transition, is consistent with that of LuAG:Ce single crystals, well coupled with the silicon photodiodes and satisfies the property requirements of a scintillator. Ce:LuAG transparent ceramics is a promising scintillating material.