Cholesteric-nematic phase-change effect in mixtures containing the liquid-crystal PCB

The anomalously-low critical field, previously reported in phase change devices that used 4-n-pentyl-4-cyanobipheny (PCB), is shown to be a result of the unusual behaviour of the cholesteric additive used. Using different additives removes the anomaly. The results allow a determination of the twist elastic constant of PCB.