DIRECT TEM IMAGING OF TUBULES IN CALCINED MCM-41 TYPE MESOPOROUS MATERIALS

Calcined MCM-41 type mesoporous samples have been characterized by tra nsmission electron microscopy(TEM). Samples are not crystalline at the atomic level. The existence of an array of long silicate tubules pack ed in honeycomb fashion, nearly always bent and curved has been eviden ced. The formation of such a silicate architecture through a liquid-cr ystal template mechanism had been hypothesized before. Equidistant par allel lines observed in this study are shown to be related to the hexa gonal repeat between tubules: the honeycomb array is sufficiently regu lar to give fringes in projection under proper orientation of the spec imen. The existence of a hypothetical lamellar phase in the calcined m aterial is not confirmed by our observations. Samples with different c ompositions all had the same general architecture.