A liquid with distinct metastable structures: Supercooled butyronitrile.
J Chem Phys
; 156(4): 044501, 2022 Jan 28.
Article
em En
| MEDLINE
| ID: mdl-35105087
ABSTRACT
The dielectric relaxation behavior of the molecular glass former butyronitrile is revisited by measuring both bulk samples cooled from the melt and samples obtained by physical vapor deposition. We find that the dielectric constant in the viscous regime of the bulk liquid is much higher than reported previously, reaching εs = 63 at T = 103 K, i.e., just above the glass transition temperature Tg = 97 K. By contrast, varying the deposition temperature and rate of vapor-deposited samples leads to dielectric constants in a range between 4.5 and 63 at T = 103 K. Values much below εs = 63 persist for thousands of seconds, where the dielectric relaxation time is about 0.1 s. The observations can be interpreted by the formation of clusters in which pair-wise anti-parallel dipole orientation is the preferred state at temperatures well below the glass transition. These non-crystalline clusters are long-lived even above Tg, where the remaining volume fraction is in the state of the equilibrium polar liquid.
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01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Chem Phys
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
Estados Unidos