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

Ordered macroporous lanthanide oxides (Eu2O3, Nd2O3 and Sm2O3) have been fa bricated using colloidal crystals of polystyrene (PS) spheres as a template in conjunction with the sol-gel method. Solidification of Ln(3+)-EDTA chel ates in the voids between the PS spheres and removal of the template by cal cination yields three-dimensional ordered macroporous oxides. X-Ray diffrac tion reveals that the phases of Eu2O3, Nd2O3 and Sm2O3 are cubic, hexagonal and cubic, respectively, and scanning electron micrography shows that thes e oxides retain the structure of the initial template and exhibit 3D long-r ange ordered close packing of pores. The properties of these oxides are exp ected to allow them to find applications in areas including separation, cat alysis and photonic crystals.