Dipolar dynamics of low-molecular-weight organic materials in the glassy state

C. Hansen, R. Richert

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60 Scopus citations


We have measured the dielectric relaxation of several low-molecular-weight glass-forming materials for temperatures ranging from 25 K to T ≈ Tg and for values of the loss tangent down to tanδ ≈ 10-7. For the materials under study (salol, glycerol, N-methyl-ε-caprolactam, 2-methyltetrahydrofuran, 3-methylpentane, and o-terphenyl) a β-relaxation appearing in quenched samples can be suppressed effectively by annealing at T < Tg, thereby facilitating the study of the dipole dynamics in the absence of the secondary process. As a general behaviour of the remaining dielectric losses at f = 1 kHz we find a variation of log10(ε″) = a + bT (b ≈ 0.015 K-1) signalling the increasing constraint in the angular degree of freedom as the temperature is lowered and a further increase or peak of ε″ in the range 25 K < T < 50 K. According to a comparison with the crystalline counterparts, the latter effects are characteristic features of the disordered solid state.

Original languageEnglish (US)
Pages (from-to)9661-9671
Number of pages11
JournalJournal of Physics Condensed Matter
Issue number44
StatePublished - Nov 3 1997
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics


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