Infrared transmittance of hybrid microwave sintered yttria

Synthesis of nano particles of yttria (Y2O3) ceramics (similar to 15 nm) by a single step auto-igniting combustion technique, followed by sintering of the sample by three variants of sintering methods viz. resistive, microwave and microwave hybrid heating to optimum density and their remarkable infrared transmission characteristics are presented in this paper. In microwave hybrid sintering there was a considerable reduction in the sintering temperature and the soaking time compared to the resistive and microwave sintering. The pellets sintered by microwave hybrid heating at 1450 degrees C for 20 min achieved a density 99.2% of the theoretical density with reduced average grain size of 220 nm and the pellet showed enhanced transmittance of similar to 80% in the visible and similar to 80% in the mid infrared region. The results clearly indicate that the yttria ultra fine nanophase powder synthesised by the single step combustion method and sintered via microwave hybrid heating shows better transmittance properties and can be used very effectively for the fabrication of infrared transparent windows and domes. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.