SEARCH Articles Figures Tables Fulcher Relaxation time Vogel-Tamman-Fulcher temperature Vogel Vogel-Fulcher Vogel-Fulcher-Tammann equation temperature dependence Vogel-Fulcher-Tammann temperature Vogel-Fulcher-Tammann-Hesse equation temperature Vogel-Tamman-Fulcher temperature Vogel-Tammann-Hesse-Fulcher temperature-time dependence