Partial Nitridation of Sr_3Al_(10)SiO_(20):Eu and its Effect on Photoluminescence Properties

摘要

The first principle calculation and Pauling's second rule predicted that an O~(2-) ion coordinated with two Al~(3+) and one Si~(4+), or Si~(4+)-O~([3])-2Al~(3+), is stabilized by cross-substitution to form 2Si~(4+)-N~([3])-Al~((3+)) configuration. Motivated by this idea, this work has attempted to synthesize a new phosphor by partial nitridation of Sr_3Al_(10)SiO_(20):Eu~(2+), which contains one set of Si~(4+)-O~([3])-2Al~(3+) per 20 O~(2-) ions. Synthesis condition of Sr_3Al_(10-x)Si_(1+x)O_(20-x)N_x:Eu~(2+) with x=1 was investigated by variation of Si_3N_4/SiO_2 ratio in the starting materials. Neutron diffraction analysis has shown that nitridation as much as x=0.6-2 was attained by supply of Si_3N_4 in excess of the stoichiometry, because Si_3N_4 is partly oxidized even by firing in reduced atmosphere. Luminescence intensity is increased by 7 times at the best by the nitridation, though little change is observed in luminescence spectra and X-ray diffraction patterns. The increased luminescence intensity results mainly from more efficient reduction of Eu~(3+) by Si_3N_4.