Thermal phase transitions from a nematic liquid-crystal phase to an isotropic phase are reported in this study. The phase transition temperature T_c under noise and DC fields was examined during continuous heating processes with different heating rates R (1–10 °C/min). T_c was determined as functions of the noise intensity V_N and the DC intensity V. Evidently, T_c shows different behavior with respect to the fields at fixed values of R. T_c decreased monotonously with V_N, whereas it exhibited nonmonotonic behavior in T_c(V). These shifts in T_c are quite different from that previously observed in the AC field. It was found that DC field-induced electroconvection is responsible for the unexpected nonmonotonic behavior. In particular, the transition between the dynamic scattering modes (i.e., DSM1 and DSM2) may be related to this behavior. The different behavior for the noise and DC fields was confirmed using various values of R. Furthermore, the present results in comparison with the previous results for the AC field were discussed.

中文翻译：

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噪声和直流场存在下向列液晶的相变温度

本研究报告了从向列液晶相到各向同性相的热相变。在不同加热速率R (1–10 °C/min)的连续加热过程中检查噪声和直流场下的相变温度T _c。T _c被确定为噪声强度V _N和 DC 强度V的函数。显然，T _c对于固定R值的场表现出不同的行为。T _c随V _N单调下降，而T _c ( V )则表现出非单调行为。T _c的这些变化与之前在交流场中观察到的变化有很大不同。研究发现，直流场引起的电对流是造成意想不到的非单调行为的原因。特别地，动态散射模式（即，DSM1和DSM2）之间的转变可能与该行为有关。使用不同的R值证实了噪声和直流场的不同行为。此外，还讨论了当前结果与之前交流场结果的比较。