Supercritical Hydrothermal Synthesis of Nano-Zirconia: Reaction Path and Crystallization Mechanisms of Different Precursors

Abstract

Nano-zirconia exhibits excellent mechanical properties (fracture toughness, hardness and flexural strength), thermal performance (thermal conductivity), optical properties and biological properties for various ceramic-based applications. Supercritical hydrothermal synthesis technology is an advanced and environmental-friendly method for preparing nanoscale powders. In this paper, the formation and crystallization of nano-zirconia during supercritical hydrothermal synthesis were systematically investigated. Different precursors (zirconium nitrate, zirconium oxychloride, zirconium acetate) reacted in supercritical water and the quality of nano-zirconia in different systems were comprehensively evaluated using XRD, TEM, IR, BET analysis. Finally, the most suitable precursor type was identified and the reaction path as well as crystallization mechanisms of different precursors were revealed.