Synthesis, Thermal Analysis, Optical, Electric Properties and Conduction Mechanism of Hybrid Halogenometallates: [N(C2H5)4]2CoCl4

The X-ray powder diffraction pattern indicates that at room temperature, [N(C2H5)(4)](2)CoCl4 crystallized in the tetragonal system with the space group P4/mmm (D-4h). The chemical composition of [N(C2H5)(4)](2)CoCl4 was discussed by a STEM-EDS. The optical properties were measured by means UV-Vis-NIR absorption spectrometry to deduce the optical bandgap E-g. Notably, [N(C2H5)(4)](2)CoCl4 exhibits a semiconducting property with a direct feature optical bandgap value of similar to 4.18 eV. Four phase transitions at T-1 = 241 K, T-2 = 303 K, T-3 = 349 K, and T-4 = 391K were confirmed by the differential scanning calorimetry (DSC) curve. The measurements of the electrical properties were performed in the 10(-1)-10(7) Hz frequency range and 200-430K temperature interval. The interpretation of Nyquist curves revealed the presence of three electrically active areas equivalent to the electrode processes, distribution of grain boundaries and bulk mechanism. The alternative current (AC) electrical conduction in [N(C2H5)(4)](2)CoCl4 was interpreted by different approaches: the overlapping large polaron tunneling (OLPT) model in phase 1, the non-overlapping small polaron tunneling (NSPT) model in phases 2 and 4, the quantum mechanical tunneling (QMT) model in phase 3 and the correlated barrier hopping (CBH) model in phase 5.

Automated summary

The study revealed the crystal structure and optical properties of [N(C2H5)(4)](2)CoCl4 at room temperature, showing its semiconductor nature with a direct optical bandgap value of around 4.18 eV, as well as multiple phase transitions at different temperatures. Electrical properties were analyzed to understand the conduction mechanisms in different phases.