Dielectric properties of LC mixture with induced antiferroelectric phase

2008 ◽  
Vol 16 (3) ◽  
Author(s):  
M. Wojciechowski ◽  
G. Bąk ◽  
M. Tykarska

AbstractMixture of two liquid crystalline components exhibits the antiferroelectric phase in a broad temperature range at room temperatures, though the two components separately do not show an antiferroelectric phase in a temperature range applied. The dielectric spectroscopy technique combined with measurements of the selective light reflection was used for identification and characterization of the phases and subphases existing in the mixture. In the SmC*A phase, the low frequency mode characteristic of antiferroelectric phase has been detected. In the broad temperature range between SmC*A and SmA* phases, no relaxation mode has been detected. The soft mode registered near the phase transition to SmA* phase follows the Curie-Weiss law.

2019 ◽  
Vol 92 (2) ◽  
pp. 173-179 ◽  
Author(s):  
Anđela Buljan ◽  
Anamarija Knežević ◽  
Irena Dokli ◽  
Andreja Lesac

The synthesis and liquid-crystalline properties are reported for novel naphthyl-based diketones incorporating variant terminal chains and lateral fluoro- substitution. Newly prepared materials exhibit a broad temperature range of the nematic phase. The study demonstrates how subtle structural modifications can be exploited to alter the efficiency of molecular packing and consequently the thermal behaviour.


2008 ◽  
Vol 77 (10) ◽  
Author(s):  
S. Kamba ◽  
D. Nuzhnyy ◽  
R. Nechache ◽  
K. Závěta ◽  
D. Nižňanský ◽  
...  

2010 ◽  
Vol 645-648 ◽  
pp. 1135-1138 ◽  
Author(s):  
Philip G. Neudeck ◽  
Michael J. Krasowski ◽  
Liang Yu Chen ◽  
Norman F. Prokop

The NASA Glenn Research Center has previously reported prolonged stable operation of simple prototype 6H-SiC JFET integrated circuits (logic gates and amplifier stages) for thousands of hours at +500 °C. This paper experimentally investigates the ability of these 6H-SiC JFET devices and integrated circuits to also function at cold temperatures expected to arise in some envisioned applications. Prototype logic gate ICs experimentally demonstrated good functionality down to -125 °C without changing circuit input voltages. Cascaded operation of gates at cold temperatures was verified by externally wiring gates together to form a 3-stage ring oscillator. While logic gate output voltages exhibited little change across the broad temperature range from -125 °C to +500 °C, the change in operating frequency and power consumption of these non-optimized logic gates as a function of temperature was much larger and tracked JFET channel conduction properties.


1994 ◽  
Vol 44 (7) ◽  
pp. 717-720 ◽  
Author(s):  
M. Kašpar ◽  
H. Sverenyák ◽  
V. Hamplová ◽  
S. A. Pakhomov ◽  
M. Glogarová

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