Al置換によるフッ素雲母の赤外線吸収スペクトル及び格子定数の変化

概要

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Series of Al-substituted fluorine micas, KMg_<2+x>Li_<1-x>(Al_xSi_<4-x-y>Ge_yO_<10>)F_2 and KMg_<2+x>Li_<1-x>(Al_xGe_<4-x-y>Si_yO_<10>)F_2 : x = 0.0-1.0, y = 0, 1 , 2, 3, were synthesized and variations of infrared spectra and lattice constants with Al-substitution were studied and compared to those with Ga-substitution reported previously. The infrared spectra of the synthesized micas varied sensitively with composition. Continuous changes in lattice constants with increasing Al-contents proved that there were complete series of solid solutions between the end member micas. Lattice constants a and b increased almost linearly with increasing Al-content in all series. However, c・sin β( basal spacing) remained almost unchanged or slightly increased in the case of Al-for-Si substitution while it decreased linearly in the case of Al-for-Ge substitution. These complicated changes of cell dimensions were explained in terms of the tetrahedral rotation angle α, the octahedral flattening angle ψ, and the change in interlayer conformation. Linear relationships between c・sin βand average radius of tetrahedral cation were obtained for Al-and Ga-micas having an x-value of 1.0 and for micas having x-value of 0.0., respectively, showing that the cell dimension and structural deformation depend essentially on both the charge balancing and the size of tetrahedral cations.
1990-05-01