Effects of LiF on the microstructure and optical properties of hot-pressed MgAl2O4 ceramics

Transparent magnesium aluminate spinel (MgAl2O4) ceramics were fabricated by hot-pressing of the MgO and α-Al2O3 powder mixture using LiF as a sintering aid. Effects of the LiF additive on densification, microstructure and optical properties of MgAl2O4 ceramics were systematically investigated. It has been found that the addition of LiF can effectively remove the porosity and increase the optical transparency of MgAl2O4 ceramics. For the spinel ceramics HP-ed at 1550 °C for 3 h with 1 wt% LiF addition, the average grain size is about 36 µm and the in-line transmittance exceeds 60% at the wavelength of 800 nm.