塩化物イオン及び臭化物イオン添加フッ化アルミニウム系ガラスにおける希土類金属イオンの酸化還元平衡

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The effect of chloride and/or bromide ions on the redox equilibrium of rare-earth ions, Sm and Yb, was investigated in an AlF_3-based YABC glass system. The large absorption bands of 4f-5d transition of Sm^<2+> and Yb^<2+> ions were found in the chlorine-doped samples in the visible and ultra-violet regions, respectively. Their intensities increased with the degree of incorporation. Change in the redox equilibrium of Yb ions was found to be a function of both the quantity and type of non-fluoride halide ions used as dopants. Br^- was about 6 times more efficient than Cl^- and co-doping resulted in a greater number of divalent Yb^<2+> ions. X-ray photoelectron spectra of Y3d and the thermodynamics data of various halide compounds and molecules reveal that the direct bond formation between rare-earth ions and non-fluoride ions and the lower free energies of mixed halide molecules would play key roles in the formation of divalent rare-earth ions in the glass melts.
1997-08-01