Synthesis of Structure and Surface Functional Rare Earth Materials

Abstract

Structure and surface functional rare earth materials were synthesized and their physicochemical properties were characterized to design high-performance materials, viz. (1) Efficient phosphors, (2) persistent spectral hole burning devices, (3) permanent magnets and (4) nitrogen storage materials: (1) Strontium borates consisting of BO₄ units, SrB₄O₇ and δ-SrB₂O₄ (high-pressure phase), were good host lattices to provide intense blue emissions owing to the lowered phonon effect of three-dimensional BO₄ network. (2) Persistent spectrum hole burning spectra were observed on the sol-gel-derived silica-based glasses dispersed with europium(III) crown ether complex, of which the mechanism was based on the reduction of Eu³⁺ ions. (3) Rare earth intermetallic compounds such as Sm₂Fe₁₇N_x (x = ∼3) and Nd₂Fe₁₄B provided high-performance bonded magnets by effective surface coating for the raw fine powders, Zn metal vapor sorption and/or silylation with alkyl silane. (4) Nitrogen storage systems were established by nitrogenation and denitrogenation cycle between the rare earth-iron intermetallic compounds and metal nitrides, by which ammonia was formed even at ambient pressure.