Thermally activated polaron tunnelling conduction mechanism in Sr2MnO4 synthesized by quenching in ambient atmosphere

The oxide Sr2MnO4 was synthesized using the solid-state reaction technique. Quenching in air from 1500 degrees C to room temperature yielded the pure phase powder of Sr2MnO4. The purity of synthesized powder was further examined by FTIR analysis. The Rietveld refinement of XRD data confirmed the tetragonal structure and I4/mmm space group. The band gap, computed from the Tauc's plot, was found to be 1.15 eV. The XPS analysis depicted the presence of Mn3+ and Mn4+ valence states. Measurement of the AC electrical conductivity over wide temperature (30 degrees C-500 degrees C) and frequency (0.020-2 MHz) ranges were carried out. The conduction mechanism changed from small polaron tunnelling (<270 degrees C) to non-overlapping large polaron tunnelling (>270 degrees C). The frequency versus imaginary part of the impedance (Z '') and modulus (M '') plots exhibited a change in the conduction domain with increase in temperature. This result was further verified by the Ghosh's scaling of the conductivity spectra.

Automated summary

The oxide Sr2MnO4 was synthesized using the solid-state reaction technique, and its purity and structure were verified through FTIR and XRD analysis. The band gap was calculated to be 1.15 eV, and XPS analysis revealed the presence of Mn3+ and Mn4+ valence states. AC electrical conductivity measurements at different temperatures and frequencies showed a change in the conduction mechanism.