Study of LiMgVO4 electrical conductivity mechanism

This paper deals with impedance spectroscopy on single-phase polycrystalline LiMgVO4 in the temperature range of 25–500 °C. Thermogravimetric measurements show a weight loss of 2.7% in the temperature range between 25 °C and 175 °C due to humidity desorption. A conductivity mechanism along the grain boundaries (agb) is identified in the specific temperature range and is attributed to a reversible humidity absorption–desorption mechanism. Equivalent circuits are drawn using the results of the impedance measurements at each temperature. A unique conduction process within the material is assigned to each element of the equivalent circuit and Arrhenius plots are plotted. The calculation of activation energy of each conduction mechanism is based on the Arrhenius plots. The activation energy Eb of the bulk conductivity mechanism was found to be 0.62 eV. The activation energy Egb of the grain boundaries conductivity mechanism was found to be 1.03 eV up to 275 °C and 0.50 eV in the temperature range of 300–500 °C. The absence of the conductivity mechanism along the grain boundaries above 175 °C can only be due to the complete removal of water from the material's grains.