Departamento de Física - UEM - Conoscopic image of a biaxial negative nematic phase in a potassium laurate-decanol-D2O mixture

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

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