Ceria doped alumina by Spark Plasma Sintering for optical applications

Al₂O₃–CeO₂ ceramics were found to be transparent in the IR range and high-traslucent in the visible range. The surface of nanometric α-alumina particles was modified by deposition–precipitation of small fractions of ceria nanoparticles. The powders were sintered using Spark Plasma Sintering. Values of Real In-line Transmittance up to 70% in the IR-Vis range have been measured. Transparency enhancement has been attributed to Cerium oxide nanoparticles located at the grain boundaries and triple points. These particles are hindering alumina grain growth during SPS at a temperature as high as 1430 °C. This effect is found to be effective under SPS low vacuum conditions and short dwell times. The optimum ceria content was found to be 0.7 wt.%. Diffusion in Al₂O₃–CeO₂ as a function of the atmosphere has been studied in diffusion couples. The results obtained by the proposed route are discussed considering the data reported in the literature for SPS_ed transparent alumina.