Fabrication and microstructural characterization of the novel optical ceramic consisting of alpha-Al2O3@amorphous alumina nanocomposite core/shell structure

摘要

In this study, alpha-Al2O3@amorphous alumina nanocomposite core-shell structure was synthesized from AICl(3) and the commercial alpha-Al2O3 nanoparticles as the starting materials via a wet chemical route. The results indicated that the shell material mainly comprised of ammonium chloride and boehmite phases. Boehmite was transformed to the amorphous and gamma-Al2O3 phases after the calcination process and the shell material was completely converted to gamma-Al2O3 at 1000 degrees C. However, for the alpha-Al2O3@amorphous alumina core-shell nanoparticles were completely converted to alpha-Al2O3 at 1000 degrees C. It can be concluded that alpha-Al2O3 core particles, as the seed crystalline, help to transforming of gamma-Al2O3 phase as the shell material directly without forming transitional phases to alpha-Al2O3. The optical polycrystalline alumina was fabricated using spark plasma sintering of alpha-Al2O3@amorphous alumina core-shell nanocomposite. The body sintered has a final density of similar to 99.8% and the in-line transmittance value is similar to 80% within the IR range.