Surface modification of zirconia with acid groups

We have studied the effect of surface modification with acids and subsequent heat treatment on the properties of hydrous zirconia. It has been shown that surface modification with phosphate and sulfate groups makes it possible not only to control the phase composition of the heat-treated oxide but also to considerably suppress particle growth. We have discussed the processes involved and shown that, in the initial stages of thermolysis, the process leads to the formation of metastable, tetragonal ZrO2, which transforms into monoclinic zirconia at higher temperatures. Surface modification with phosphoric acid stabilizes tetragonal zirconia up to 850°C.