The phase-stabilized behavior of Sc2O3–Y2O3 co-doped ZrO2 nanopowders by co-precipitation synthesis

Abstract

Single stabilizer-doped ZrO2 has drawbacks such as inferior mechanical properties and thermal stability, making it difficult to obtain ZrO2 ceramics with good density and high crystallinity. Thus, it is expected that ZrO2 is doped and modified by two or more stabilizers. In this paper, the Sc2O3–Y2O3–ZrO2 nanocomposite ceramic powders were prepared using ZrOCl2⋅8H2O, ScCl3⋅6H2O, and YCl3⋅6H2O as raw materials and polyvinylpyrrolidone as dispersant. They calcined at diverse temperaturesby the pressureless sintering-assisted co-precipitation method after being pressed into disc shape. Sc2O3 and Y2O3 were added as ZrO2 stabilizers to ameliorate the lack of insufficient mechanical properties and high-temperature stability of ZrO2 ceramics caused by single doping. To study the stability of the phases at high temperatures, the specimens were characterized by TG-DTG, XRD, Raman, SEM, FT-IR, etc. The effects of different pH valuesand different calcination temperatures on the Sc2O3–Y2O3–ZrO2 nanocomposite ceramics were investigated. It was demonstrated that ternary doping has very excellent phase stability. After calcination no monoclinic phase appeared, and the precursor samples were transformed from amorphous to a large amount of tetragonal phases and a few cubic phases. The samples at pH = 10 and calcination temperature of 1000 °C showed the best stabilization, the most uniform grain development, the best crystallinity, the most regular morphology, the highest tetragonal phase content of 89.2 %, the stabilization rate of 94.58 %, and the highest relative density of 98.75 %. The results show that this nanocrystalline powder can be used to prepare high-density nanoceramics. Furthermore, the activation energy for grain growth of Sc2O3–Y2O3–ZrO2 nanocomposite ceramics was calculated as 13.87 kJ/mol. This paper provides a theoretical and experimental research basis for the controlled synthesis of Sc2O3–Y2O3–ZrO2 nanocomposite ceramics using a pressureless sintering-assisted co-precipitation method.