Resolving Detail
With the preferred geometry (alternative geometries have been used for example by Mardix et. al. 1987 [9]) and the improved resolution available from second generation synchrotrons it is now possible to confidently resolve complex features such as LPP’s and 1DD layers in coalescence with low period polytypes.
The magnified detail shows two LPP’s assigned as 40H and 64H/192R (10) along with the common 6H polytype. The crystal which also contains 1DD’s (5 µm & 40 µm) is fully described as :
6H+1DD+6H+64H/192R+1DD+40H
Of the 135 crystals 21 have been found to contain a long period polytype and 19 with a one-dimensionally disordered layer ? 10 µm.