The dynamics of organic compounds 2-cyclo-octylamino-5-nitropyridine (COANP), (S)-2-N--(methylbenzylamino)-5-nitropyridine (MBANP), 2-(N-prolinol)-5-nitropyridine (PNP), and N-(4-nitrophenyl)-(L)-prolinol (NPP) were studied by dielectric relaxation spectroscopy in the frequency range of 10 Hz-2 MHz and differential scanning calorimetry (DSC). The dielectric and DSC studies showed that COANP, MBANP and PNP underwent glass transition. However, NPP crystallized so rapidly upon cooling that the glass state could not be observed. It was found that the crystalline process of COANP did not slow the structure relaxation of COANP glass. The relaxation times fitted well to the empirical Vogel-Fulcher equation = exp[Ea/kb(T-TVF)]. The activation energies Ea and the Vogel-Fulcher temperature TVF were 54.5 meV and 239 K for COANP, 86.2 meV and 249 K for MBANP and 84.9 meV and 245 K for PNP, respectively. The crystalline temperatures of COANP and MBANP were given as 300 K and 330 K, respectively. An anomalous behaviour of the dielectric permittivity of PNP glass was observed.
Pockels and Kerr cells were fabricated by growing N.(4-thtropheny1)-L-pro1mol (NPP) crystal films between two transparent fused quartz plates on which indium-tin-oxide layers were deposited. Both linear and quadratic electro-optic effects of the crystals with thickness of 5 and 10 .tm were examined by an ac modulation method. Large modulation signals were observed with a low driving voltage, the figure of merit of the electro-optic phase retardation were estimated to be 8.Ox 10"It is suggested that the electro-optic cells are promising for application because of their durability, relative easy manipulation during crystal growth and high figure of merit.
Two-step kinetic crystallization processes from the glass-like
disordered state of N-(4-nitrophenyl)-(L)-prolinol have been found during
the monitoring of the time evolution of dielectric strength and these are
discussed within steady state theory. The dynamics of structure relaxation
in the disordered state have been investigated by broadband dielectric
spectroscopy. The temperature dependence of the relaxation times is
described by the Vogel-Fulcher equation with an anomalous pre-exponential
parameter. The anomaly is discussed within the framework of the two-order
parameter model of glass formation proposed by H Tanaka (1999 J.
Chem. Phys. 111 3163; 1998 J. Phys.: Condens. Matter 10
L207).
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