# X-Ray Scattering Study of Restacking Transitions in the Crystalline-B Phases of Heptyloxybenzylidene Heptylaniline (7O.7)

 Title: X-Ray Scattering Study of Restacking Transitions in the Crystalline-B Phases of Heptyloxybenzylidene Heptylaniline (7O.7) Author: Collett, Jeffrey; Sorensen, L. B.; Pershan, Peter S.; Als-Nielsen, J. Note: Order does not necessarily reflect citation order of authors. Citation: Collett, Jeffrey, L. B. Sorensen, Peter S. Pershan, and J. Als-Nielsen. 1985. X-ray scattering study of restacking transitions in the crystalline-B phases of heptyloxybenzylidene heptylaniline (7O.7). Physical Review A 32(2): 1036-1043. Full Text & Related Files: Collett_X-ray_1985.pdf (1.674Mb; PDF) Abstract: This paper reports a comprehensive x-ray diffraction study of the structure and the restacking transitions which occur within the crystalline-B phases of N-[4-(n-heptyl)oxybenzylidene]-4’-(n-heptyl)aniline (7O.7). Between $$63^{\circ}C$$ and $$59^{\circ}C$$, this system exhibits a rich structural behavior with a series of three transitions involving restacking and subtle changes in the intralayer packing. In order of decreasing temperature, the structures are hexagonal close packed $$(69–63^{\circ}C)$$, orthorhombic F $$(63–60.1^{\circ}C)$$, monoclinic C $$(60.1–59.75^{\circ}C)$$, and simple hexagonal $$(59.75–55^{\circ}C)$$. In the last three phases, there is also a long-wavelength modulation $$(\lambda \sim 100\mathring{A})$$ in which the smectic layers are displaced along their normals. The wave vector of the modulation lies in the plane of the smectic layers directed along a reciprocal-lattice vector and exhibits a weak $$(\sim 20%)$$ temperature variation. Both low-resolution (rotating-anode) and high-resolution (synchrotron) measurements of the structures and of the diffuse scattering are reported. Published Version: doi:10.1103/PhysRevA.32.1036 Terms of Use: This article is made available under the terms and conditions applicable to Other Posted Material, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#LAA Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:10357690 Downloads of this work: