The electrical conduction in three glasses of the system Agx(ASo.4So.6)lO0_ x
with x=6, 15 and 25, has been studied. Below To, the dc
conductivity increases with increasing absolut6 temperature in accordance
with the thermal activation formula: o= C exp(-E,~/2kT). The addition of
silver (6-25 at.%) to As2S_ leads to a big decrease in E~ (1.29 to 0.38 eV),
relative small increase Jin or.t.(20°C) (l.4xlO -12 to 5.6xi0 -9 ohm-lcm-l),
and very pronouced decrease in the pre-exponent C. The small variation in the
value of C of As2S 3 and Ag6(As 0 4Sn 6)94, (4 and 0.2 ohm-lcm-l), confirms the
non-variation of the orp~ment'st~Octure due to the addition of up to 6 at.%
Ag. The decrease in E~ for the 6 at.% Ag glass is discussed in terms of
Mott's charged dangling bonds. The X-ray radial distribution function tetra-
hedral base structure for higher Ag percentage glasses is confirmed by the
value of E~ and the very low value of C (less than 10-4 ohm-lcm-l). |
