Reverse Micelle Synthesis And Consolidation Of Zirconia Nanopowders

This study describes the synthesis of zirconia and 3 mol% yttria-stabilized zirconia (3YSZ) nanoparticles in a reverse micelle solution. The methodology involves the precipitation reaction of zirconium oxychloride with ammonia. The effects of temperature on the resulting powders are described. The synthesis produced loose aggregates of tetragonal zirconia nanoparticles ranging between 1--5 nm. Reaction conditions, including water/AOT ratio, aging time, and washing method, were varied to investigate their influence on nanoparticle formation. Elimination of remnant AOT was performed with various solvents. Hydrogen peroxide was more efficient at this task compared to ether, isooctane, and ethanol. Calcination of the as-synthesized powders improved crystallinity and led to particle growth. The activation energy for grain growth was found to be around 40 kJ/mol. The tetragonal pure zirconia powders changed to monoclinic phase upon treatment at 500°C. The 3YSZ powders were consolidated using spark plasma sintering to a density >98% in 20 minutes.