Transparent ceramics prepared from ultrapure magnesium aluminate spinel nanopowders by spark plasma sintering

Abstract

We have studied the properties of transparent magnesium aluminate spinel ceramics prepared by spark plasma sintering (SPS) of ultrapure nanopowders. The starting powders, of ≃ 99.98% purity, ranging in specific surface area from 30 to 160 m²/g, were prepared through the hydrolysis of alcoholic solutions of magnesium aluminum alkoxide complexes, followed by calcination at temperatures from 900 to 1100°C. SPS was carried out at 1450°C, with the holding time at the highest temperature not longer than 15 min. The transparent ceramic samples thus prepared have a transmission of up to 73% in the visible and IR spectral regions (λ = 2.5–5.0 µm). The crystallite size in the ceramics is 0.2–0.4 µm, and their microhardness is HV0.1 = 14.8–16.2 GPa.