Vogel-Fulcher-Tammann equation ionic conductivity

The conductivity of ionic liquids often exhibits classical linear Arrhenius behavior above room-temperature. However, as the temperature of these ionic liquids approaches their glass transition temperatures (Tg) the conductivity displays significant negative deviation from linear behavior. The observed temperature-dependent conductivity behavior is consistent with glass-forming liquids, and is often best described using the empirical Vogel-Tammann-Fulcher (VTF) equation. [Pg.153]

One of the important properties of a polymer electrolyte leading to its development activity is the ionic conductivity. Temperature dependence on the conductivity of amorphous polymer electrolytes generally follows the Vogel-Tammann-Fulcher [VTF] equation [14] ... [Pg.932]

The brief discussion above shows that the structure of a polymer electrolyte and the ion conduction mechanism are complex. Furthermore, the polymer is a weak electrolyte, whose ions form ion pairs, triple ions, and multidentate ions after its ionic dissociation. Currently, there are several important models that attempt to describe the ion conduction mechanisms in polymer electrolytes Arrhenius theory, the Vogel-Tammann-Fulcher (VTF) equation, the Williams-Landel-Ferry (WLF) equation, free volume model, dynamic bond percolation model (DBPM), the Meyer-Neldel (MN) law, effective medium theory (EMT), and the Nernst-Einstein equation [1]. [Pg.361]

The temperature dependence of the ionic conductivities for the HBP-SA and the HBP-SA-co-HBP-Ac membrane in the temperature range of 60-150°C is shown in Fig. 13.1. Ionic conductivity data of the polymer and electrolyte membrane are typically interpreted using the Vogel-Tamman-Fulcher (VTF) equation (Vogel, 1921 Tammann and Hesse, 1926 Fulcher, 1925) ... [Pg.529]

Methoxyethyl (methyl) carbonate (MOEMC) was investigated by Gu et al. [39]. The ionic conductance processes occurring in MOEMC and other asymmetric alkyl methyl carbonate-based solutions obeyed the Vogel-Tammann-Fulcher (VTF) mechanism. The VTF equation is... [Pg.165]