Ferroelectric properties and alternative current conduction mechanisms of lithium rubidium molybdate

The lithium rubidium molybdate compound LiRbMoO4 was prepared by the solid-state reaction method. XRD spectra revealed a single phase material with an orthorhombic structure. The internal Raman modes were observed at room temperature. The dielectric measurement exhibited three subsequent phase transitions: two structural transitions at the neighborhood of 397K and 420K followed by a ferro-paraelectric transition at 424K. The Nyquist plot was proved to be a non-Debye relaxation mechanism. The combined spectroscopic plots of the imaginary part of electric impedance and modulus in the temperature range of 581-718K at various frequencies confirmed the non-Debye behavior. The AC conductivity was found to follow the Jonscher's universal dynamic law omega(S), and the overlapping large polaron tunneling model (OLPT) was proposed to describe the conduction mechanism.