Fine-grained transparent MgAl2O4 spinel obtained by spark plasma sintering of commercially available nanopowders

A high transmittance/small grain size combination for pure spinel ceramics from commercially available nanopowders without sintering aids can be obtained by SPS sintering. By using a low heating rate <= 10 degrees C/min and a sintering temperature <= 1300 degrees C, a transparent polycrystalline MgAl2O4 spinel was fabricated by SPS with an in-line transmission of 74% and 84% for 550 nm (visible) and 2000 nm (NIR) wavelengths respectively. A small average grain size of about 250 nm was obtained and the pores located at the multiple grain junctions have a mean size of about 20 nm. The high in-line transmission is linked not only to the low residual porosity but particularly to the very small size of pores. (C) 2011 Elsevier Ltd and Techna Group Sri. All rights reserved.