Template-free solvothermal synthesis of size-controlled yttria-stabilized-zirconia hollow spheres

Tetragonal yttria-stabilized-zirconia (YSZ) hollow spheres were prepared through a template-free solvothermal method in a homogeneous solution of butanol/acetylacetone or ethanol/acetylacetone with ZrOCl2·8H2O and Y(NO3)3·6H2O as the reaction reagents. The hollow spheres were composed of nanometer-sized particles. The sizes of the hollow spheres could be tuned from 300 nm to 900 nm by changing the concentration of ZrOCl2·8H2O or altering the solvent. Time-dependent experiments showed that the hollow spheres transformed from amorphous solid spheres composed of nanoparticles. The Ostwald ripening process is proposed to explain the formation of the hollow structures. Er3+ doped zirconia (ZrO2) hollow spheres were also synthesized using the same method. Characteristic emission patterns (515–565 nm) and (640–690 nm) were observed from Er3+ doped zirconia hollow spheres with 980 nm excitation.

► Yttria-stabilized-zirconia hollow spheres are prepared.
► The sizes of the hollow spheres can be controlled.
► The ZrOCl2·8H2O concentration has an important role on the product.
► The Ostwald ripening process is elaborated.
► The hollow spheres after doping Er3+ show the up-conversion property.