Structural investigation of ETS-4

The experimental findings of this work suggest that ETS-4 is structure related to zorite but is not the synthetic counterpart of this mineral, as proposed previously. Si-29 MAS n.m.r. results are not entirely in agreement with the zorite structure. These spectroscopic results can be explained by the presence of a second intergrown phase that would not easily be observed by techniques such as scanning electron microscopy. X-ray diffraction patterns of zorite and ETS-LF are, however, very similar. Two approaches have been taken to speculate on the structure of this material. First, ETS-4 is viewed as an intergrowth system of zorite with nenadkevichite. The second approach derives mainly from the work on ETS-10 where a number of defects were observed in the HREM images of this material. Combining both approaches seems to be a potential way of explaining the structure of ETS-4.