Low-Temperature Hydrothermal Synthesis of Yttrium-Doped Zirconia Powders

• Published in: Journal of the American Ceramic Society Vol. 82; no. 5; pp. 1169 - 1174
• Main Authors: Tsukada, Takayuki, Venigalla, Sridhar, Morrone, Augusto A., Adair, James H.
• Format: Journal Article
• Language: English
• Published: Westerville, Ohio American Ceramics Society 01.05.1999; Blackwell; Wiley Subscription Services, Inc
• Subjects: Chemistry; Colloidal state and disperse state; Elements and non-metal compounds (oxides, hydroxides, hydrides, sulfides, carbides, ...); Exact sciences and technology; General and physical chemistry; Inorganic chemistry and origins of life; Powders; Preparations and properties; Yttrium Oxides; Chemical preparation; Crystallization; Stabilized zirconia; Experimental study; Hydrothermal condition; Powder; Low temperature
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.1999.tb01891.x

The feasibility of low‐temperature synthesis of yttrium‐doped zirconia (Y‐ZrO2) crystalline powders in aqueous solutions at lessthan equal to100°C has been evaluated, and the hydrothermal crystallization mechanism for Y‐ZrO2 powders also has been investigated. Coprecipitated (Y,Zr) hydroxide gel, mechanical mixtures of Y(OH)3 and Zr(OH)4 gel, and Y(OH)3 gel have been reacted in boiling alkaline solutions. Coprecipitated (Y,Zr) hydroxide gel crystallized to cubic or tetragonal Y‐ZrO2 at pH 13.9. The yttrium content in the powder synthesized from coprecipitated (Y,Zr) hydroxide is consistent with the initial precursor solution composition, as expected from the similarity in solubility of Zr(OH)‐5 and Y(OH)‐4. A diffusionless mechanism for the transformation of the (Y,Zr) hydroxide gel to Y‐ZrO2 is proposed, and the phase stability in aqueous solution is discussed in terms of an in situcrystallization model. It is also demonstrated through thermodynamic arguments with experimental verification that the stable form of the Y‐ZrO2 at 25°C is the anhydrous phase, not the metal hydroxide as previously thought.