A TGA INVESTIGATION OF HYDRATED MONOCLINIC ZIRCONIA

Thermogravimetric analysis (TGA) was used to monitor the surface hydro xyl and carbonate concentrations on porous zirconia after various vapo r- and liquid-phase treatments. After equilibration with humid nitroge n, each of the surface zirconium atoms bears a single hydroxyl group a nd all surface oxygen atoms are present as bridged hydroxyl groups. Hy drochloric acid and sodium hydroxide treatments further increase the s urface hydroxyl group concentration. In the presence of sufficient wat er, carbon dioxide chemisorption is inhibited. Once adsorbed, however, surface carbonates and bicarbonates are not removed by hydrochloric a cid, sodium hydroxide or sodium fluoride washings.