Production of ultrafine ZrO 2 and Y-doped ZrO 2 powders by solvent extraction from solutions of perchloric and nitric acid with tri-n-butyl phosphate in kerosene

Abstract

Zr(IV) with or without addition of Y 3+ was extracted with tri-n-butyl phosphate (TBP) in kerosene from solutions of perchloric acid and nitric acid with the formation of the third-phase microemulsion. The loaded organic phase was precipitated with a controlled amount of 25% ammonia in aqueous solution. After washing with water and vacuum freeze-drying, the precipitate was calcined to oxide at 600°C. The as-prepared powders were characterized by thermogravimetric differential thermal analysis (TG-DTA), BET adsorption, X-ray diffractometry (XRD), and transmission electron microscopy (TEM). It was found that the specific surface areas of ZrO 2 and Y-doped ZrO 2 powders were 30–58 m 2/g and 233 m 2/g respectively. The relative content of tetragonal ZrO 2 decreased with increasing pH of precipitation. The Y-doped ZrO 2 was found to be amorphous with flocculent morphology and without body pores. The particulate ZrO 2 was 10 nm in diameter on average. Powders prepared in this way were tested by energy dispersive analysis with X-rays (EDAX) and were found to contain no other contaminants.