DENSITY, DIFFERENTIAL THERMAL-ANALYSIS AND DIRECT-CURRENT CONDUCTIVITY OF SB10S90-XGEX CHALCOGENIDE GLASSES

The glass-transition temperature, T(g), and the crystallization temper ature, T(c) for glassy Sb10S90-xGex samples were increased by increasi ng the Ge content. This was attributed to the closeness of the network by bridging Sb and/or S atoms with additional Ge atoms to form harder Ge-Sb and/or Ge-S bonds. The direct current (d.c.) electrical conduct ivity for the system Sb10S90-xGex shows semiconducting behaviour with increasing temperature. At low temperatures, the conductivity was attr ibuted to a hopping conduction mechanism, while at high temperatures i t was due to regular band-type conduction, The activation energy, DELT AE(sigma) and the conductivity, sigma(O) were increased at low Ge cont ents. This may be related to the entrance of Ge atoms into the S-S cha ins. On the other hand, the increase of the Ge content above 20 at % l ead to a conversion of the behaviour of the DELTAE(sigma) and sigma(O) from the insulating character of S to the semiconducting character of Ge.