Thermal and dielectric studies on orientationally disordered crystal: cyclobutanol

• Published in: Indian journal of physics 2022, Vol.96 (7), p.1991-1999
• Main Authors: Manal Poovingal, N N, Shahin Thayyil, Mohamed, Afzal, Aboothahir, Govindaraj, G
• Format: Article
• Language: English
• Subjects: Alcohols; Astrophysics and Astroparticles; Broadband; Coupling (molecular); Crystal structure; Dielectrics; Freezing; Melt temperature; Organic crystals; Original Paper; Phase transitions; Physics; Physics and Astronomy; Polymorphism; Slopes; Solid phases; Thermodynamic properties
• ISSN: 0973-1458; 0974-9845
• DOI: 10.1007/s12648-021-02150-w

Dielectric response and thermal behavior of an orientationally disordered organic crystal cyclobutanol were critically investigated with differential scanning calorimetry and broadband dielectric spectroscopy (10 −2 to 10 7  Hz) from the deep glassy crystalline state to its melting temperature. The effort was made to understand the relaxation dynamics of plastic crystals of diverse characteristics, which lack translational degrees of freedom and to explore features of different transition and to get a comprehensive understanding on glass-forming dynamics. Information about polymorphism, solid–solid phase transitions, their kinetic freezing, structural and secondary relaxation were explored. The structural relaxation showed non-Arrhenius T-dependence and non-Debye features in the frequency domain. The resolved secondary relaxation in cyclobutanol was identified to be intermolecular or Johari–Goldstein (JG) relaxation from coupling model predictions. The investigated sample was revealed as an intermediate system in Angell’s criteria of strong–fragile classification. The data on cyclobutanol filled the gap for attaining a comprehensive picture on low molecular cyclic alcohols, where T g showed a progressive increase with molecular weight, while the steepness index exhibited a smooth switch over from fragile to strong behavior.