EFFECTS OF HEAT-TREATMENT ON IR-SPECTRA AND B-AXIS VALUES OF CATION - EXCHANGED FLUORINE MICAS

Effects of heat treatment on IR spectra and b-axis values for various M3+, M2+, M+-exchanged fluorine micas were investigated. The Si-O stretching band frequencies and b-axis values changed on heating for the exchanged micas having smaller interlayer cation such as Al3+, Ni2+, etc, whereas those didn't change for the exchanged micas having large cations such as Ba2+, K+ and Cs+. The wavenumber of Si-O stretching band for the exchanged micas heated at 550-degrees-C increased in the order of Al3+>Ga3+>Fe3+>Ni2+>Co2+>Mn2+-exchanged micas, corresponding to the order of ionic radius of interlayer cation. The b-axis values of the exchanged micas heated at 500-degrees-C are closely related to the ionic radius of interlayer cation, indicating that the smaller cation can migrate more deeply into the hexagonal hole and extend it during heating. The swelling ability of exchanged fluorine mica were decreased by heating, which can be explained by the degree of migration of interlayer cation.