Industrial precipitation of zirconyl chloride: the effect of pH and solution concentration on calcination of zirconia

Abstract

In situ and ex situ X-ray diffraction, and transmission electron microscopy were used to investigate thecalcination of four samples of zirconia manufactured using two different zirconia reactant solution concentrations (0.81M and 1.62M) with precipitation carried out at pH 3 and 12. The calcinations wereinvestigated over the temperature range from room temperature to 1000"C. It was found that varyingthe precipitation conditions resulted in differing calcination routes; it is believed that variations in particlesize and initial degree of hydration are responsible for these differences. It was also found that theinitial phase produced after calcination was tetragonal zirconia, which underwent a process of crystallitegrowth to a size of # 30nm before transformation from tetragonal to monoclinic.