Hydrothermal synthesis and phase stability of Pb stabilized ZrO2 nanoparticles

Abstract The Pb doped metastable tetragonal ZrO 2 ( t- ZrO 2 :Pb) nanoparticles have been successfully synthesized by hydrothermal method. Pb ion doping has great effects on the phases, crystallite sizes and optical band gaps. Systematic structural characterization revealed that the introduction of Pb ion results in lattice expansion. The as-prepared t -ZrO 2 :Pb with ca 4–6 nm in size has high specific surface area (>150 m 2 /g) and narrow particle size distributions. The diffuse reflectance spectra investigated that the band gap shifts from ultraviolet ( E g  = 5.19 eV) for pure ZrO 2 to the visible region for t -ZrO 2 :Pb and the gap can be effectively adjusted with the content of Pb in nanocrystals. Through thermal treatment, Pb ion doped in ZrO 2 crystals was excluded with increasing temperature. At 800 °C, the three t -ZrO 2 :Pb samples of ZPO-2, ZPO-3 and ZPO-4 still contained the pure tetragonal phase, in which Pb content were not reduced to zero, while the transformation from tetragonal to monoclinic phase occurred due to zero Pb content in ZPO-1. The reason to this transformation and stabilized mechanism of Pb ion in ZrO 2 were discussed.