| 초록 |
Transparent polycrystalline ceramics have been investigated for infrared (IR) windows, solid-state laser medium, scintillators and bio-applications in order to substitute for the single crystal. To obtain the fully dense polycrystalline ceramics, special sintering technologies are used such as vacuum sintering, vacuum hot pressing and spark plasma sintering (SPS). While the full density can be obtained via sintering in a vacuum, the final products show black color which is so-called discoloration. The oxygen vacancy in the sintered ceramics can be removed conventionally by post-annealing in air or in oxygen atmosphere. The post-annealing is insufficient to improve the optical transmittance due to the pore development in the bulk, and it inevitably deteriorates the optical performance. Therefore, it is difficult to obtain the highly transparent ceramics by post-annealing. In order to solve this problem, we introduced new strategy to fabricate the transparent Y2O3 ceramics preventing the formation of oxygen vacancy during the vacuum sintering. The suppression of the oxygen vacancy generation during vacuum sintering is demonstrated successfully by introducing the Y2O3-ZrO2 dual powder bed considering the thermodynamics. The as-sintered Y2O3 ceramics shows almost the theoretical transmittance from the visible to the IR range. |
