Search results for "Conoscopy"
showing 2 items of 2 documents
Shape-persistent V-shaped mesogens—formation of nematic phases with biaxial order
2006
A homologous series of shape-persistent V-shaped molecules has been designed to form the biaxial nematic phase. Phenyleneethynylene moieties are attached to a bent fluorenone unit to create an apex angle of about 90°, which is determined from the single crystal structure. Two mesogens, one symmetric and another unsymmetric, have been synthesized by attaching a cyano group to one or both of the peripheral phenyl units, respectively. These groups introduce local dipoles essential for the formation of the nematic phases. The tendency to form a crystalline phase is reduced by laterally substituted hexyloxy chains which allow the nematic phase to be supercooled to a glassy state. Two of the thre…
Structural and Optical Homogeneity in Lithium Niobate Crystals of Low Photorefractivity
2015
Comprehensive studies by Raman and photo-induced light scattering complemented by laser conoscopy and electron spectroscopy of structural and optical homogeneity of nominally pure and modified lithium niobate crystals are reported.