title: Capacitance and optical studies of elastic and dielectric properties in an organosiloxane tetrapode exhibiting a N(B) phase.
abstract: Biaxial (N(B)) and uniaxial nematic (N(U)) phase behavior was detected and confirmed for an organosiloxane tetrapode material using capacitance and birefringence measurements. Elastic constants, permittivities at two distinct low frequencies, and birefringencies were determined as a function of temperature over both the N(U) and the N(B) phase ranges. The N(U)-N(B) transition is clearly observed in the birefringencies and conoscopy data. A temperature dependent cross-over frequency is also detected in this material for the permittivities, allowing the electrical switching of both planar and homeotropic aligned samples.
authors.affiliation: IST-Technical University of Lisbon, Dept. de Física, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Polineni
authors.forename: J L
authors.initials: JL
authors.lastname: Figueirinhas
authors.forename: C
authors.initials: C
authors.lastname: Cruz
authors.forename: D A
authors.initials: DA
authors.lastname: Wilson
authors.forename: G H
authors.initials: GH
authors.lastname: Mehl