Ni^<2+>置換フッ素四ケイ素雲母の合成と性質

概要

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Various Ni^<2+>-substituted tetrasilicic micas having high contents of Ni^<2+>such as KNiMgLi(Si_4O_<10>)F_2, KNi_2Li(Si_4O_<10>)F_2 and KNi_<2.5>(Si_4O_<10>)F_2, were synthesized at ca.900℃ through solid-state reaction techniques. Lattice constants a, b, c decreased with increasing Ni^<2+>-substitutions, reflecting the decrease in the ionic radius of Ni^<2+> against Mg^<2+>. UV-visible spectra of Ni^<2+>-micas were vary similar to those of[Ni(H_2O)_6]^<2+>. This can be explained in terms of the nephelauxetic series F^-<H_2O<O_a(apical oxygen)as well as the spectrochemical series F^-<H_2O<O_a. IR spectra showed that the tetrahedral distortion changes with increasing Ni^<2+>-substitutions, i.e., the interatomic distance of Si-O_a lengthens while that of Si-O_b(basal oxygen)shortens. Ni^<2+>-micas exhibited paramagnetism when the Ni^<2+> content was smaller than 2.0 mol in octahedral sites, however, antiferromagnetism seemed to appear at larger substitutions of 2.5 mol Ni^<2+> per formula unit.
社団法人日本セラミックス協会の論文
1995-10-01