The thermal decomposition of zirconium oxyhydroxide

Abstract

The thermal decomposition of zirconium oxyhydroxides prepared by the mixture of aqueous zirconium oxychloride solutions and aqueous solutions of sodium hydroxide or ammonium hydroxide under various conditions has been examined by thermogravimetry, differential thermal analysis, X-ray diffraction study and infrared spectrophotometry. As a result, it is seen that the thermal decomposition of zirconium oxyhydroxide, in which the composition is ZrO_2-x(OH)_2x⋅yH₂O where x≤2 and 1≤y<2, proceeds according to the following process:

$$\begin{gathered} {\text{ ZrO}}_{{\text{2}} - {\text{x}}} ({\text{OH}})_{2{\text{x}}} \cdot y{\text{H}}_{\text{2}} {\text{O}} \to {\text{ amorphous ZrO}}_{\text{2}} \to \hfill \\ {\text{metastable tetragonal ZrO}}_{\text{2}} \to {\text{ monoclinic ZrO}}_{\text{2}} \hfill \\ \end{gathered}$$