Dielectric characteristics and phase transitions in Tl[.sub.x] solid solutions

This paper reports on a study of the electrical conductivity and permittivity of Tl[(In[S.sub.2]).sub.1-x][(Fe[Se.sub.2]).sub.x] crystals as functions of composition and temperature. It has been found that the permittivity decreases in magnitude, while the electrical conductivity increases with increasing x. Crystals Tl[(In[S.sub.2]).sub.1-x][(Fe[Se.sub.2]).sub.x] have been observed to undergo a sequence of phase transitions characteristic of TlIn[S.sub.2], which manifests itself in formation of anomalies in the σ = f(T) and ζ = f(T) temperature dependences. It has been shown that as x increases, the phase transition temperatures decrease, while the temperature region within which the incommensurate phase persists broadens slightly.