For bulk samples of the quenched TlzsCei4Sess either as-prepared or isochronically
annealed for one hour at different temperatures up to 150 “C, the current-voltage characteristics
at different temperatures of measurements (T) and of annealing (Tan) were
non-linear especially when the applied potential difference exceeds certain value which
is dependent on both T and T,,. The field dependence of the current denity could
be described by an empirical power equation. The field enhancement of the electrical
conductivity followed an exponential equation. The temperature dependent characteristic
length a(T) possessed maximum value at certain values of T and T,,, and
becomes lower by about one order of magnitude by annealing. Annealing in the range
(loo-130 “C) was associated with appearance of semimetallic behaviour which characterized
the relatively low range of T. Semimetallic-semiconductor transition occurred
at particular temperatures depending on that of annealing. Otherwise, semimetallic
behaviour extended over the whole range of T. The band to band activation energy
changed with the pre-exponential conductivity according to the Meyer-Neldel rule. In
the range T,, <_ 90 “C, Mott’s formula for hopping conductivity seemed applicable and
the characteristic temperature, the density of the localized states, the average hopping
distance and the hopping energy were calculated