50687-45-1Relevant articles and documents
Smectic-smectic phase transitions in binary liquid-crystalline mixtures of DB5-T8
Fontes, Ernest,Lee, Wah Keat,Heiney, Paul A.,Nounesis, George,Garland, Carl W.,et al.
, p. 3917 - 3929 (2007/10/02)
We have used high-resolution x-ray diffraction and ac calorimetry to study the liquid-crystalline smectic-A-smectic-A phase transitions in binary mixtures of polar mesogenic compounds DB5 phenyl ester> and T8 ethenyl> phenyl ester>.A detailed synthesis for each of these compounds is presented.The smectic A1 phase in this system shows two collinear diffuse x-ray maxima at incommensurate wave vectors, indicating a tendency to form the predicted Ai1 phase with two strongly coupled density modulations having incommensurate wavelengths.The Ad peak position, while both temperature and concentration dependent, is remarkably constant along the N-Ad phase boundary.In the vicinity of 16 mol percent T8, both the x-ray and heat-capacity results are reproducibly history dependent.The simultaneous observation of sharp A2 and Ad peaks most likely results from phase coexistence, but a condensed incommensurate Ai2 phase cannot be ruled out.
