The Effects of Sintering Atmosphere on the Fabrication of Transparent Polycrystalline YAG Ceramics

Abstract

In this paper, a mixture of commercial Al2O3 and Y2O3 nanopowders was prepared according to the stoichiometric ratios of YAG (Y3Al5O12) with 0.5 wt% tetraethyl orthosilicate (TEOS) as a sintering aid. The effects of air and vacuum sintering atmosphere were examined on the phase transformation, densification, in-line transmission, microstructure evolution, grain size distribution, sintering trajectories, and grain growth map of the YAG ceramics. The results showed that all samples were pure YAG phase. Nearly pore-free microstructure (99.8%) and narrow grain size distribution (4-10 μm) with an average grain size of 7 μm was obtained for the sample sintered in the vacuum atmosphere, while both inner and inter pores with abnormal grain growth, wider grain size distribution (9-27 μm) with the average grain size of 12 μm were detected in air atmosphere. Also, the results showed that the specimens sintered in vacuum atmosphere had higher relative densities and smaller grain sizes at all sintering temperatures for 6 h. The maximum transmittance at 1064 nm of the YAG ceramics sintered at air and vacuum atmosphere was 26% and 68%, respectively.