Ferroelectric and electrical properties of LiNaWO4 compound

The aim of this work is to elaborate the LiNaWO4 compound, using the solid state method, then to characterize it using an XR study which confirms that it crystallizes in the orthorhombic system with P222 as space group and with the lattice parameters a = 12.82 angstrom, b = 17.49 angstrom, c = 7.25 angstrom and alpha = beta = gamma = 90 degrees. The differential scanning calorimetry (DSC) shows two endothermic peaks at T-1 = 388 K and T-2 = 500 K. The first peak is detected by the dielectric study, attributed to a phase transition from a ferroelectric phase to a paraelectric one, while the second peak indicates the presence of a phase transition, confirmed later by the result of the electrical study. All modes pertaining to vibrations of WO42- tetrahedral appear in the Raman spectrum. Moreover, its impedance response is modeled by a single cell formed by a parallel combination of R//C//CPE, i.e. the response of our compound is that of the grain. The variation of the sigma(g) and sigma(dc), as a function of temperature, confirms the phase transition observed in the calorimetric study at T-2. The conduction mechanism in the two phases indicates that the first phase (I) is described by the CBH model and the second phase by the OLPT model.