Glycothermal synthesis of 3 mol% yttria stabilized tetragonal ZrO2 nano powders at low temperature without mineralizers

Abstract

Tetragonal 3YSZ (3mol% yttria-stabilized zirconia) nanoparticles were synthesized at temperature as low as 200°C through a glycothermal reaction using coprecipitated amorphous hydrous gel of ZrCl4 and YCl3·6H2O as precursors and 1,4-butanediol as solvent. XRD and TEM data support that glycothermal processing method provides a simple low temperature route for producing highly crystallized tetragonal ZrO2 nanoparticles without mineralizers, which could also be extended to other system. Raman analysis also indicated that 3YSZ nanoparticles synthesized in glycothermal condition had tetragonal phase without any trace of monoclinic phase. The as-prepared 3YSZ nanoparticles have spherical morphology with an average crystal size of 7–10nm and agglomerated into spherical shape with a diameter of about 100–200nm. The tetragonal phase remained stable with heat treatment when the calcinations of the as-synthesized powder were carried out from 400 to 1400°C. The combination of uniform glycothemally-synthesized tetragonal 3YSZ nano-powder and two-step sintering can suppress grain boundary migration but not affect grain boundary diffusion without long annealing period. Fine-grained microstructure with 100–500nm was obtained without abnormal growth although the pellet was fully dense and had 98.1% of the theoretical density at 1400°C. The pellets sintered at 1350 and 1400°C exhibit activation energies for conduction in range 0.84eV, which are close to the values usually found for zirconia-based solid electrolytes.