Thermal stability and field assisted sintering of cerium-doped YSZ ceramic nanoparticles obtained via a hydrothermal process

Abstract

Abstract. Owing to its extraordinary range of properties, yttria-doped zirconia holds a unique place among the ceramic oxide systems. To improve the properties for some specific custom design applications, co-doping with other rare earth oxides such as ceria is needed. The aim of this paper is to identify the correlations between the phase composition evolution with increasing thermal treatment temperature in order to establish the thermal stability in connection with the ceria content and how does it influence the yttria-stabilised zirconia microstructure. The ZrO 2 -3Y 2 O 3 -nCeO 2 (n = 3, 6 and 9 wt.%) samples were obtained by a hydrothermal process and submitted to a thermal treatment up to 1600°C. Intensive characterization was performed via X-ray powder diffraction and EDX analysis. It was found that up to 400°C, a monophasic structure was formed. At higher temperatures tetragonal zirconia is formed as a major phase with the presence of secondary monoclinic and cubic phases, depending on the Ce content and thermal treatment temperature. Sintered compacts with densities up to 99.5% from the theoretical density were obtained starting from the 6%CeO 2 -3%Y 2 O 3 -ZrO 2 -nanostructured powders using a special field-assisted (FAST) sintering process. With increasing CeO 2 content to 9% only, tetragonal zirconia with 6-9 nm crystallite sizes is formed during the FAST sintering process.

Design, Fabrication, and Characterization of New Materials Based on Zirconia Doped with Mixed Rare Earth Oxides: Review and First Experimental Results

“…Melting point, • C 2700 Evaporation rate µm/h × 10 −5 at 1650 • C 670 Density, g/cm 3 5.6 at 1927 However, at temperatures above 1200 • C in the long term, YSZ loses its phase stability but the main critical issue is calcium-magnesium-alumino-silicate (CMAS) attack that lowers the thermal insulating power [18,19]. Therefore, it is desired to develop new TBCs that can operate at a temperature above 1200 • C. An actual research topic is doping ZrO 2 ceramics with different rare earth oxides due to their high temperature transformation and the low thermal conductivity, which allow to increase the operating temperatures of turbines.…”

“…Necessity for better performance and efficiency in applications across stationary power plants, aerospace and automotive industries has led to the development of thermal barrier coatings (TBCs) and multi-layer coating systems over the last 50 years [1]. During recent years it was demonstrated that co-doping of zirconia ceramics with rare earth oxides (REOs) may avoid grain size coarsening due to interface segregation, enhancing its ionic conductivity and sinterability [2,3]. The co-doping of zirconia with different REOs was reported to improve the thermal properties of thermal barrier coatings and oxidation properties due to reduction of mechanical stresses and porosity in the oxide layers [4,5].…”

Nanostructured Pure and Doped Zirconia: Synthesis and Sintering for SOFC and Optical Applications

“…Fang et al [58] showed enhanced densification of zirconia containing ceramic matrix composites by microwave processing. Tamburini [64]. The hydrothermally synthesized powders after were mixed with a solution containing 6 wt% polyvinyl alcohol as binder and spray dried using a LabPlant spray drier system (air speed of 3.5 m/s at evacuation and feeding rate of 617 ml/h using a 0.5 mm nozzle).…”

Synthesis of magnesium aluminate spinel—An overview

“…Table 2 depicts the various parameters/features associated with some of the synthesis methods for spinel formation and also includes the challenges associated with each methods. 138,139 Solid-state reactions are not ideal for producing reactive and fine MgAl 2 O 4 spinel powders because calcination at high temperatures causes grain growth and severe agglomeration of MgAl 2 O 4 particles. Spinel powder (MgAl 2 O 4 ) can be made by milling MgO and Al 2 O 3 in a highenergy ball mill, followed by calcination to reduce the temperature of the solid-state reaction.…”