A new route to three-dimensionally well-ordered macroporous rare-earth oxides
Ordered macroporous lanthanide oxides (Eu2O3, Nd2O3 and Sm2O3) have been fabricated using colloidal crystals of polystyrene (PS) spheres as a template in conjunction with the sol–gel method. Solidification of Ln3+–EDTA chelates in the voids between the PS spheres and removal of the template by calcination yields three-dimensional ordered macroporous oxides. X-Ray diffraction reveals that the phases of Eu2O3 , Nd2O3 and Sm2O3 are cubic, hexagonal and cubic, respectively, and scanning electron micrography shows that these oxides retain the structure of the initial template and exhibit 3D long-range ordered close packing of pores. The properties of these oxides are expected to allow them to find applications in areas including separation, catalysis and photonic crystals.