X-ray investigations of a nematic compound exhibits smectic B phaseAuthor(s): S.Mohyeddine, R.Somashekar, D.Revannasiddaiah
Wide angle X-ray patterns were recorded at different temperatures in the nematic and smectic-B phases of 4-hexyl-4ï¢-[2-(4-isothiocyanatophenyl) ethyl]-1,1ï¢-biphenyl. Layer thickness, inter planer spacing and hence the thermal expansion coefficient were determined in smectic-B phase at various temperatures. The orientational distribution function f(ï¢) has been calculated fromthe angular distribution of the X-ray intensities. The orientational order parameterï ï¼P2ï¾has been determined from f(ï¢). Further, following Line ProfileAnalysis (LPA), it is examined theX-ray profiles of outer and inner rings to compute the crystallite size and intrinsic strain present in the sample. It has been observed that the crystallite area in the smectic-B phase is larger than that of crystalline phase, which essentially indicates a reordering of molecules with a stronger inter/ intra molecular interaction in smectic-B phase. In addition, it is also observed that nano-crystallite area in SmB phase decreases with increase in temperature.