Molecular dynamics and crystallization behavior of chiral isooctyloxycyanobiphenyl as studied by dielectric relaxation spectroscopy

The complex dielectric permittivity of right-handed isooctyloxycyanobipheny l (IOOCB) has been studied in the frequency range 10(-1)-10(5) Hz and over a wide temperature range. On cooling the isotropic liquid a supercooled liq uid is formed that becomes a glass below 220 K. On heating the glass, the m aterial crystallized at about 250 K and remelted at 285 K. The dielectric a lpha-relaxation in the isotropic liquid was found to conform with the Vogel -Fulcher Tamman equation for its average relaxation time and the Kohlrausch -Williams-Watts function for its spectral line shape. The isothermal crysta llization of the supercooled liquid to form a crystalline solid was monitor ed by dielectric relaxation spectroscopy, and the Avrami exponent was found to be 1.51 at a crystallization temperature of 263 K.