Pure Tetragonal ZrO₂ Nanoparticles Synthesized by Pulsed Plasma in Liquid

Abstract

Pure tetragonal phase ZrO2 (t-ZrO2) nanoparticles of sizes smaller than 5 nm were synthesized by a pulsed plasma in liquid (PPL) method, a one-step synthesis method: in an ammonia solution with no use of dopants or annealing for stabilization. Lattice parameters of the obtained samples refined by the Rietveld method revealed structural differences compared with the nanoparticles obtained by other methods such as the sol–gel method. The intrinsic properties of the pulsed plasma in liquid method and the alkaline environment (OH–) may be responsible for the stabilization of tetragonal zirconia, while the oxygen deficiency level checked by X-ray Absorption Near Edge Structure (XANES) is smaller than 1%, leading to light gray color of samples and a limited stabilization effect on the tetragonal phase. The particles displayed a higher UV absorption property than a commercial stabilized zirconia sample. Also, the emission lines of Zr I atoms and Zr II ions were observed by an optical emission spectrum to gather information on the synthesis mechanism.