Wladimir S. Braga, Oscar R. Santos, Danilo D. Luders, Anderson R. Sampaio, Newller M. Kimura, Manuel Simões, Aantonio J. Palangana

JOURNAL OF MOLECULAR LIQUIDS – Volume: 187; Pages: 20-23; DOI: 10.1016/j.molliq.2013.05.002

The discotic nematic (ND)–biaxial nematic (NB)–calamitic nematic (NC) phase transitions are studied in a potassium laurate–decanol–D2O mixture by optical conoscopy. The ND+ (NC) phase is uniaxial positive (negative) as expected. Nevertheless, inside the biaxial range, beyond the known biaxial positive (NB+) nematic phase we have also found a biaxial negative (NB) nematic phase optically characterized through conoscopic images. A transition point from a NB+ to a NB configuration is determined and discussed in this work.