stacking disorder
X-ray X-press ( SNYDER@xray.alfred.edu )
Mon, 12 Feb 1996 7:41:02 GMT
The problem that N. Dragoe refers to is typically not related to an
incommensurate modulation but instead due to a two dimensional stacking
disorder. We commonly see this effect in the Bi and Tl Ruddlesden-Popper
superconducting phases which have very long c axis and commonly have bands
of 2201, 2212, 2223, 2234 and even 2235 intergrown. These intergrowths cause
a complex modulation of the c axis d values. A excellent description of
this phenomenon is given in the two chapters by R. Reynolds in the book Modern
Powder Diffraction edited by D. Bish and J. Post and published by the
Mineralogical Society of America.
Bob Snyder