One-step hydrothermal synthesis of yttria-stabilized tetragonal zirconia polycrystalline nanopowders for blue-colored zirconia-cobalt aluminate spinel composite ceramics

Abstract

A novel approach for the preparation of blue-color giving zirconia nanopowders by doping of 3 mol% Y2O3 through simple one-step hydrothermal process is proposed. A blue-color giving yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) powders were prepared by urea-based solution, zirconium acetate, CoCl2·6H2O and AlCl3 precursors in hydrothermal vessel at 24 h, 150 °C and 20 bars. Based on the results, the synthesized blue-color giving Y-TZP nanopowders have entirely tetragonal structure as mono phase with 3.8 ± 0.2 nm average grain size and (Y, Co, Al)xZrO2; x ≤ 0.03 at. with chemical composition. Thermal treatment was also applied to synthesized Y-TZP powders at 1200 °C and 1450 °C to observe the color evolution. Only sharp blue was obtained in Y-TZP powders resulting the development of zirconia-cobalt aluminate spinel (ZrO2-CoAl2O4) composite ceramic structure for both temperatures after heat-treatment. Herein, not only formation of CoAl2O4 but also incorporation of cobalt (Co) and aluminum (Al) into the Y-TZP grains plays a critical role on evolving of blue color. This synthesized Y-TZP nanopowders can be a good candidate for one-step production of blue-color sintered ZrO2-CoAl2O4 spinel composite ceramics in numerous ceramic applications due to their superior structural and functional properties.