Electric Conductivity and Electrode Polarization as Markers of Phase Transitions

Dielectric polarization and electric polarization of electrodes are the common features of polar materials. We described methods to analyze their contributions and showed that both dependencies on temperature of dielectric conductivity and electrode polarization and the exponents characterizing these dependencies are excellent markers of phase transitions. Proposed methods were applied to several compounds, such as liquid crystals, pharmacological compounds, monoalcohols, polyalcohols, and various thermodynamic phases. Common behavior was noted for materials under study. In similar phases, various substances have the same values of the exponents characterizing electric conductivity and contribution from the electrode polarization. These exponents show discontinuities at phase transition temperatures between crystal-like and liquid-like phases

Thermo-optical analysis (TOA) as a tool of melting phenomena investigations

In the work, after preliminary discussion of the complexity of the phenomenon of melting chemical compounds, two basic research methods are presented: calorimetric methods and thermooptical method. The physical basis of the five main calorimetry techniques is now detailed (adiabatic calorimetry, differential thermal analysis – DTA, differential scanning calorimetry with heat compensation – DSC heat compensated, differential scanning calorimetry with heat flow – DSC heat flux and differential scanning calorimetry with temperature modulation – MDSC) and thermo-optical techniques used in phase transitions investigations. The advantages and disadvantages of these methods are shown in numerous examples and the accuracy attainable by the individual measuring techniques is compared

Distinguishing the Focal-Conic Fan Texture of Smectic A from the Focal-Conic Fan Texture of Smectic B

This publication presents methods of distinguishing the focal texture of the conical smectic phase A (SmA) and the crystalline smectic B phase (CrB). Most often, characteristic transition bars are observed in polarized light at the temperature point of the SmA–CrB phase transition. TOApy software transforms each image from a series of images recorded during POM observation to a function of light intensity versus temperature. Thermo-optical analysis is a powerful quantitative tool to notice this phase transition, but it has some limitations. The other applied method, the local binary pattern (LBP) algorithm, with high probability, detects differences between the textures of the conical focal fan of the SmA and CrB phases. The LBP algorithm is an efficient tool for texture classification