Effect of quenched disorder on the RI-RV, RII-RI, and liquid-RII rotator phase transitions in alkanes

Area of Science:

• Materials Science
• Condensed Matter Physics
• Physical Chemistry

Background:

• Disorder can influence phase transitions by altering interactions between order parameters.
• Understanding these effects is crucial for designing materials with specific thermal properties.

Purpose of the Study:

• To investigate how disorder affects the coupling between distortion and tilt angle order parameters during the R(I)-R(V) phase transition in alkanes.
• To analyze the impact of varying concentrations of silica nanoparticles on alkane phase transition characteristics.

Main Methods:

• Specific heat measurements were performed on alkanes containing different concentrations of silica nanoparticles.
• The study focused on the R(I)-R(V), R(II)-R(I), and liquid-R(II) phase transitions.

Main Results:

• Disorder significantly shifted the R(I)-R(V) transition towards a second-order character.
• The R(II)-R(I) transition's first-order character was maintained but its features attenuated with increasing disorder.
• The liquid-R(II) transition split into two distinct features, similar to isotropic-nematic transitions in liquid crystals.

Conclusions:

• Disorder plays a critical role in modulating the nature and characteristics of phase transitions in alkanes.
• The addition of nanoparticles provides a method to tune the thermodynamic behavior of these materials.