Vapor-phase assisted sintering of lutetium oxide

Abstract

Conventional methods of green-body formation of powder compacts, along with temperature/pressure processing methods, were optimized to sinter and post-HIP Lu2O3 compacts to optical transparency (99.1 % of theoretical transparency at 1100 nm). Fissures between remnants of spray-dried granules, yielding opaque spheroids around them, were eliminated by lower temperature heat treatment schedules which minimized fissure coarsening via preferential intragranular densification. A key development was the use of LiF vapor produced adjacent to the compact in the furnace environment, which physisorbed onto particle surfaces of the pre-sintered compact. This acted as a grain growth inhibitor and hence sintering aid.