Effect of LiF on the optical transmittance of magnesium aluminate spinel

The effect of LiF as a sintering aid to the optical transparency of magnesium aluminate (MgAl2O4) spinel ceramics is studied. The spinel ceramics is prepared in a process proved to be suitable for commercial production. LiF, in different concentrations ranging from 0-2.5 wt%, is doped into MgAl2O4 powders prepared by sol-gel method. Sample MgAl2O4 ceramic discs are fabricated by ball milling, cold pressing, and hot-pressing, or hot-isostatic-pressing of the powder mixtures. Optical transparency measurements show that, hot-pressed samples exhibit higher transparency when more LiF is added. While for hot-isostatic pressed samples, excessive LiF content leads to a decrease in optical transparency. The optimal LiF doping quantity is suggested for the present technique.