Development of translucent calcia stabilised zirconia ceramics via conventional sintering in air

Translucent, monoclinic-free, novel calcia-stabilised zirconia ceramics were developed utilising conventional (pressureless) sintering. The 10 mol% CaO-doped zirconia (10CaSZ) ceramic depicted a maximum transmittance of 81% at 600 nm for a 0.6 mm thick pellet while for 3 mol% CaO-doped zirconia (3CaSZ) phase-pure tetragonal system, the value was recorded as 59% at the same wavelength and thickness. The ultrafine (similar to 3 nm) nanoparticles sintered via two-step sintering process yielded full densification (> 99%) at temperatures as low as 1150 degrees C. The average grain size of sintered 3CaSZ ceramic was 85 nm. For 10CaSZ ceramic, it increased from 170 nm to 0.76 mu m with elevated sintering temperatures. The increase of sintering temperature ensured different microstructure from ultrafine grains, a bimodal grain size distribution, and ultimately leading to a grain-locking morphology. The influence of microstructure and constituent phases (tetragonal and cubic) on total forward transmittance in the visible range was analysed and explained.