Abstract
We have examined the densification of 12CaO·7Al2O3 (C12A7), which has a microporous lattice framework with a cavity of ∼0.4 nm. Fully densified translucent ceramics are obtained when hydrated C12A7 powders prepared as precursors are sintered in a dry oxygen atmosphere at 1300°C. The average transmittance between 400 - 800 nm for 1 mm thick samples is improved up to ∼70% with a 48-hour increase in the sintering time. Dissociation of water molecules at the grain-pore interface into grains to entrap hydroxide ions in the crystallographic cage, and release of the hydroxide ions into the atmosphere during the sintering procedure are considered to play crucial role in the pore annihilation processes.
