A new route to three-dimensionally well-ordered macroporous rare-earth oxides

Abstract

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.