STRUCTURAL STUDIES OF JENNITE AND 1.4 NM TOBERMORITE - DISORDERED LAYERING ALONG THE [100] OF JENNITE

Transmission electron microscopy of synthetic jennite reveals strong s treaking in the electron diffraction patterns along the [100], along w hich dark-held imaging and lattice fringing confirm the presence of a layering with a striation-like morphology, The average periodicity bet ween the layers is similar to 35 Angstrom; however, there is significa nt variation around this value in the range of 20-40 Angstrom, which i s in agreement with the range of periodicities that are associated wit h the streaking in the diffraction patterns. These results clearly dem onstrate the presence of a layering along the [100] with a periodicity that varies spatially throughout the specimen, which results in the p resence of a disordered modulated structure. We believe that the disor der is induced by frozen-in fluctuations in the local calcium:silicon ratio, which correspondingly results in fluctuations in the local stru ctural order and periodicity of the modulated structure. similar studi es of 1.4-nm tobermorite have revealed streaking along the [100]; howe ver, it was weak and diffuse.