Synthesis of Nanosize Yttria-Stabilized Zirconia by a Molecular Decomposition Process

摘要

Nanosize yttria-stabilized zirconia (YSZ) was synthesized by a novel approach based on molecular decomposition. In thisapproach, yttria-doped BaZrO3 (Y—BaZrO3) or yttria-dopedNa_2ZrO_3(Y-Na_2ZrO_3) precursorss were first synthesized fromBaCO_3, ZrO_2, and Y_20_3 or BaCO_3 and commercial YSZ forY-BaZrO_3, and from Na_2CO_3 and YSZ for Y—Na_2ZrO_3, bya conventional solid-state reaction method. The precursors were then boiled to leach away the unwanted species, BaO or Na_2O,either in a dilute HNO_3 solution in water in the case of Y-BaZrO_3, or in deionized water in the case of Y-Na_2ZrO_3.During boiling in HNO3 or water, the residue of Zr-Y-O skeleton formed fine, nanosize YSZ particles. The particle size of as-synthesized nanosize powders estimated from X-ray dif-fraction peak broadening was approx 2-3 nm, while that estimated from specific surface area measurements by BET adsorption isotherm was ~ 15 nm. Examination under a transmission elec-tron microscope showed that the crystallite size was approx 5 nm.Samples were also examined by Raman spectroscopy to deter-mine the crystallographic polymorph of the YSZ formed. Sub-aequent heating in air led to particle growth. However, even when the particles were heated to a temperature as high as 1000 deg C, the particle size was well in the nanosize range.