Dielectric properties of C₆₀under high pressure

Abstract

The dielectric properties of C60 have been measured as functions of temperature and hydrostatic pressure in the ranges 80–370 K and 0–0.8 GPa. The results show sharp anomalies at the rotational transition above 260 K and large relaxation peaks associated with the rotational ‘glass transition’. From the measured frequencies of the loss peaks we calculate the energy barrier for molecular jumping between the ‘pentagon’ and ‘hexagon’ molecular orientations. The energy barrier increases by 13% GPa−1.

Dielectric properties of C60 and Sc3N@C80 fullerenol containing polyurethane nanocomposites

“…Relevant to these results are prior studies indicating that solid C 60 arrays rotate almost freely in a rotationally disordered high‐temperature, face‐centered cubic phase (above 260 K at atmospheric pressure). This motion is said to slow down and is transformed into a ratcheting or rocking motion in an orientation‐ordered simple cubic phase at low temperatures and high pressures . Su et al demonstrated a structural phase transition at 260 K as well as an anomaly at 90 K resulting from a glass transition.…”

“…This motion is said to slow down and is transformed into a ratcheting or rocking motion in an orientation-ordered simple cubic phase at low temperatures and high pressures. [38][39][40] Su et al 38,39 demonstrated a structural phase transition at 260 K as well as an anomaly at 90 K resulting from a glass transition. Furthermore, these investigators observed a Debye-like relaxation in the dielectric response, e 0 and tan d versus f curves at three temperatures for C 60 (OH) 29 and Sc 3 N@C 80 (OH) 18 are provided in Figures 3 and 4, respectively.…”