Series of Ga- and Al-Substituted Na-fluorine micas NaMg
2+xLi
1-x(T
xSi
4-x-yGe
yO
10)F
2 and NaMg
2+xLi
1-x(T
xGe
4-x-ySi
yO
10)F
2;
x=0.0-1.0, T=Ga, Al,
y=0, 1, 2, 3, were synthesized. Variations of infrared spectra, lattice constants and swelling properties were studied, and compared with those of corresponding K-series micas. Continuous changes in basal spacing (
c·sinβ) with increasing Ga- and Al-contents proved that there were complete series of solid solutions between the end member micas with an exception of NaMg
3(AlSi
3O
10)F
2. Linear relations between
c·sinβ or
b-axis values and mean radius of tetrahedral cation were obtained for Ga- and Al-substituted Na-micas having
x-value of 1.0. However, the
b-axis values of Na-micas are far smaller than those of corresponding K-analogues, demonstrating that the degree of distortion in tetrahedral rotation angle α and octahedral flattening angle ψ is determined by the size of interlayer cation as well as that of tetrahedral cation. The values of α for Na-micas increased with the amounts of Ga- and Al-substitution. Na-micas lose also their swelling ability with increasing Ga- and Al-substitution. The loss of hydration property of interlayer cation results from the increase of α and the change of charge balancing, which increase the stability of interlayer structure.
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