论文标题
相过渡研究液晶DIO，用铁电夜间氮，列表和中间相以及与铁电列中的混合物以及通过绝热扫描量热法的混合物和混合物。
Phase transitions study of the liquid crystal DIO with a ferroelectric nematic, a nematic and an intermediate phase and of mixtures with the ferroelectric nematic compound RM734 by adiabatic scanning calorimetry
论文作者
论文摘要
绝热扫描量热法（ASC）能够同时提供特定的焓H（t）和特定的热容量CP（T），并且是确定过渡顺序并在预处理前热行为上提供高分辨率信息的重要工具。在这里，我们在复合DIO和RM734混合物上报告了ASC结果。两种化合物均表现出低温铁电列相（NF）和高温副列（N）。在DIO中，这两个相通过中间相（NX）分离。 H（T）和CP（T）的详细数据表明，在整个组成范围内所有混合物中都存在中间相，尽管随着DIO（XDIO）的摩尔分数降低，温度宽度较大。两个过渡的XDIO依赖性可以通过二次函数很好地描述，并且两个过渡都是弱的一阶。对于NF-NX转变，DIO的NX-N转变的真正潜热为0.0075 +/- 0.0005 J/g和0.23 +/- 0.03 J/g，在RM734中的NF-NF-NF-NF-NF-NF-NF-nf-nf-nf-nf-nf值的价值约为0.115 J/g。在混合物中，两种过渡潜热随着XDIO的降低而逐渐减少。在所有NX-N转变中，预处理波动效应都没有，这些转变纯粹是弱的，但一级非常弱。与RM734一样，从NF到较高温度阶段的过渡表现出很大的预科前行为。 CP（t）的功率定律分析导致DIO的有效临界指数为0.88 +/- 0.10，并且在混合物中，该值降低，XDIO降低至0.50 +/- 0.05，报道为RM734。相图的理想混合物分析与理想的混合行为一致，用于总过渡焓变
Adiabatic scanning calorimetry (ASC) is capable of providing simultaneously the specific enthalpy h(T) and the specific heat capacity cp(T), and is an important tool to determine the order of transitions and to render high-resolution information on pretransitional thermal behavior. Here we report on ASC results on the compound DIO and on mixtures with RM734. Both compounds exhibit a low-temperature ferroelectric nematic phase (NF) and a high-temperature paraelectric nematic (N). In DIO these two phases are separated by an intermediate phase (Nx). Detailed data of h(T) and cp(T), indicated that the intermediate phase was present in all mixtures over the complete composition range, albeit with strongly decreasing temperature width with decreasing mole fraction of DIO (xDIO). The xDIO dependence of the two transitions could be well described by a quadratic function and both transitions were weakly first order. The true latent heat of the Nx-N transition of DIO was as low as 0.0075 +/- 0.0005 J/g and 0.23 +/- 0.03 J/g for the NF-Nx transition, about twice the previously reported value of 0.115 J/g for the NF-N transition in RM734. In the mixtures both transition latent heats decrease gradually with decreasing xDIO. At all the Nx-N transitions pretransition fluctuation effects are absent and these transitions are purely but very weakly first order. As in RM734 the transition from the NF to the higher temperature phase exhibits substantial pretransitional behaviour. Power law analysis of cp(T) resulted in an effective critical exponent of 0.88 +/- 0.10 for DIO and this value decreased in mixtures with decreasing xDIO towards 0.50 +/- 0.05 reported for RM734. Ideal mixture analysis of the phase diagram was consistent with ideal mixture behavior for the total transition enthalpy change
