Effect of Nb doping on epsilon negative behaviour of Sr2MnO4

Solid-state ceramic route was used to synthesize certain Nb doped compounds of the system Sr2Mn1-xNbxO4 (x = 0.1, 0.2, 0.3, 0.4, 0.5) in air. Out of these, the x = 0.4, 0.5 compositions were found to consist of an impurity of Sr8Nb4O18, which elucidates a solubility limit of Nb in the Sr2MnO4. Permittivity and AC conductivity studies with respect to frequency and temperature exhibited negative permittivity in the entire range of the measurement (30-600 degrees C) for x = 0.1, 0.2 compositions, whereas in the case of x = 0.3, 0.4, and 0.5 compositions, the same behaviour was seen above 80, 180, and 230 degrees C, respectively. The plasmonic oscillations of charge carriers may be responsible for the negative permittivity behaviour, which is analysed by the Drude-Lorentz model. Compositional and temperature dependent sign of the permittivity of the system Sr2Mn1-xNbxO4 makes this system promising materials for switching action in the wide frequency range and temperature range.

Automated summary

The solid-state ceramic method was used to synthesize Sr2Mn1-xNbxO4 compounds, and impurities were found in certain compositions. The permittivity and AC conductivity experiments showed different behaviors at different temperatures, possibly due to plasmonic oscillations of charge carriers. This indicates the potential of the Sr2Mn1-xNbxO4 system for switching action.