Fabrication of transparent MgAl2O4 spinel polycrystal by spark plasma sintering processing

Transparent spinel can be fabricated without any sintering aids by spark plasma sintering (SPS) processing for only a 20 min soak at 1300 °C. For heating rates <10 °C min−1, the spinel exhibits an in-line transmission of 47% for a visible-wavelength of 550 nm and a fracture strength of ∼500 MPa. By means of low heating rate SPS processing, high transmission and strength can be attained mainly by reducing the residual pores to <0.5%.