フッ素四ケイ素雲母結晶における希土類イオンの固溶性と固着

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Synthesis of Ln^<3+>-substituted tetrasilicic fluorine micas [K_<1-x>Ln_xMg_<2-2x>Li_<1+2x>(Si_4O_<10>)F_2; Ln= Ce, Nd, Eu; x= 0.0-0.2] was undertaken by solid state reaction and melting methods. Eu^<3+>-substituted mica synthesized by the melting method had the largest solid solubility, i.e., x=0.10. The solid solubility of rare earth ions in mica structure depends on the radius of rare earth cations, resulting in the order Eu^<3+>>Nd^<3+>>Ce^<3+>. Highly Ln^<3+>-substituted fluorine micas were synthesized by ion exchange-fixation method from expandable Nataeniolite [Na_<0.8>Mg_<2.2>Li_<0.8>(Si_4O_<10>)F_2] and altered tetrasilicic fluorine mica [K_xNa_<1-x>Mg_<2.5> (Si_4O_10)F2; x≧0.18]. Houtoionic Ln^<3+>-exchanged micas obtained from Na-taeniolite didn't lose their rehydration properties upon heating even at 900℃. The degree in rehydration upon heating for homoionic Ln^<3+>-exchanged micas also decreased in the same order Eu^<3+>>Nd^<3+>>Ce^<3+>. This order is explained in terms of the polarizing power of interlayer Ln^<3+> ions. However, (Ln^<3+>, K^+)-exchanged micas obtained from altered tetrasilicic micas with NaB (C_6H_5)_4 treatment showed complete fixation of interlayer Ln^<3+> ions upon heating at 400℃, probably due to the effect of residual K^+. They lost thoroughly rehydration property. This allows us to synthesize nonexpandable fluorine micas having the highest content of rare earth cations. Ce^<3+>-substituted micas thus obtained showed strong UV-absorptivity.
社団法人日本セラミックス協会の論文
1998-04-01

フッ素四ケイ素雲母結晶における希土類イオンの固溶性と固着

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