Electrical transport as a function of temperature in hexacyanoferrate complexes

The electrical conductivity as a function of temperature and the current–voltage dependences of potassium and nickel hexacyanoferro and ferri complexes, have been determined. Charge transfer via the electron delocalization along overlapping dz2 orbitals of the iron to π* orbitals of the ligands (–C≡N) as well as the ionic conduction via Fe2+, Fe3+, K+, and Ni2+ cations are considered as the main sources participating in the conduction processes. The energy gaps, as calculated from the observed maximal absorption wavelengths of ultraviolet and visible spectra, and the activation energies for the free carriers, from the temperature dependence of the electrical conductivity measurements, are consistent with those of semiconductor materials.