Electronic structure calculations for ZnFe₂O₄

Local density approximation was applied to scrutinize the electronic structure and magnetic properties of the spinel ferrite ZnFe2O4. Various cation distributions were established to obtain the ground state for the system. In magnetic crystals, the position of the atoms is not enough for symmetry determination. A structure prediction by decreasing the octahedral point group symmetry O-h of Fe to D-4h, C-4v, and C-3v was carried out. The effect of the exchange and correlation terms on the band structure of ZnFe2O4 was studied by the generalized gradient approximation + the Hubbard correlation parameter U. The optimized structure parameters, which are in good agreement with the experimental values, were used as the input parameters for the calculations. In agreement with experimental studies, the semiconducting behavior for the studied compound, taking the effect of spin arrangement on symmetry into account, was obtained

AC conductivity and dielectric properties of In

Stoichiometric In2S3 films were prepared by thermal evaporation technique onto clean glass substrates. According to X-ray investigations, the as-deposited films were in amorphous state. Both the ac conductivity and dielectric constants were measured in the frequency range 100 Hz−100 kHz at different temperatures. Different parameters such as the frequency exponent parameter s, the density of states near the Fermi level $N(E_{\rm F})$, the activation energy $(\Delta E)$ and the optical band gap Eg of In2S3 amorphous thin films were estimated. The hopping conduction was recognized as the conduction mechanism for the investigated films