Dielectric properties, conduction mechanism, and possibility of nanodomain state with quantum dot formation in impurity-doped gamma-irradiated incommensurate TlInS_2

摘要

Temperature-dependent dielectric and conduction properties of the impurity-doped and gamma-irradiated samples of TlInS_2 semiconductor-ferroelectric with incommensurate phase are presented. As found, in both cases a stable relaxor state is emerging in the material with temperature provided that the central ion in InS_4 tetrahedron is replaced by an impurity atom such as Mn or Cr, or radiation dose exceeds 400 Mrad. Same as NMR-studies, the present work drives to a conclusion that In-displacements are among the components of the order parameter of the incommensurate phase transition. The origin of the non-activated conductivity observed in the relaxor state of TlInS_2 is assumed to be resonance tunneling executed by charge carriers from electron levels in the band gap through potential barriers created by incommensurate superstructure.