Hot pressing of Yb:Y2O3 laser ceramics with LiF sintering aid

Transparent ytterbium-doped yttria ceramics, 2 at.% Yb:Y2O3, were fabricated by hot uniaxial pressing in vacuum at 1550 °C/50 MPa followed by a two-stage Hot Isostatic Pressing (HIPing) at 1200–1400 °C/100 MPa, using nanopowders obtained by self-propagating high-temperature synthesis (with lithium fluoride serving as a sintering aid). The addition of LiF during the powder synthesis markedly changed the morphology of powders, and at the stage of hot pressing, drastically reduced the carbon contamination of ceramics, as well as stimulated sintering without formation of the liquid phase. The spectroscopic properties of ceramics were studied. The stimulated-emission cross-section for Yb3+ ions is 0.90 × 10−20 cm2 at 1030.4 nm and the luminescence lifetime is 797 μs. A continuous-wave 2 at.% Yb:Y2O3 ceramic laser generated an output power of 735 mW at 1027–1034 nm with a slope efficiency of 64.5% and a laser threshold of 0.28 W.