Crystal Structures and Properties of MMX-Chain Compounds Based on Dithiocarboxylato-Bridged Dinuclear Complexes - Material Designs and New Physical Properties in MX-and MMX-Chain Compounds - page 164

Fig. 9.13 (a) Pressure dependence of the electrical resistivity of [Pt 2 (EtCS 2 ) 4 I] 1 (2)[ 65 ].
(b) Temperature dependences of the electrical resistivity at 0, 2.2, 4.0, and 8.0 GPa

9.2.5.3 [Pt 2 (n-PrCS 2 ) 4 I] 1 (3)

The temperature dependence of electrical resistivity of [Pt 2 ( n -PrCS 2 ) 4 I] 1 (3) along
the 1D chain is represented in Fig. 9.14a [ 34 ]. The electrical conductivity along the
c axis (1D chain direction) of 3 is 0.16-0.34 S cm 1 at 300 K, which are about two
order of magnitude smaller than those of 1 and 2 [ 31 , 32 ]. This is consistent with the
appearance of the Bragg reflections with the twofold periodicity of a -Pt-Pt-I-
period, indicating the valence-localized state corresponding to a static ACP or
CDW state. The electrical resistivity shows a thermally activated behavior with
activation energy of 363 meV in the temperature range of 245-320 K, but exhibits
an apparent deviation from the thermally activated behavior in the temperature
range of 320-359 K. Resistivity jump due to the first-order phase transition is also
observed at 359 K. On the other hand, the thermoelectric power shows almost
temperature independent behavior ( VK 1 ) in the range of 330-360 K

(Fig. 9.14b ). Above the phase transition temperature, the thermoelectric power
tends to increase slightly with increasing temperature.

40 m