Hot-pressed Dy-alpha-sialon ceramics, using LiF as a sintering additive, were fabricated at lower temperatures (<= 1650 degrees C). Some of the densified samples possessed higher hardness and fracture toughness up to 19.00-20.00 GPa and 4.00-6.00 MPa.m(1/2), respectively. The amount of LiF had a strong effect on the densification behavior in sialon preparation. As one of the experimental results, the sample with 0.1 wt% of LiF additive sintered at 1600 degrees C produced an optical translucence of about 50% in the range of 1.5-5.0 mu m wavelengths. The maximum infrared transmission reached similar to 60% at a wavelength of 2.4 mu m. It is inferred that these more easily sintered materials would be practical for optical applications in certain fields.