Studies of structural, spectroscopic and electrical properties of sodium molybdate ceramics

Anhydrous polycrystalline sodium molybdate (Na₂MoO₄) ceramics has been prepared by a solid-state reaction technique. The formation of the compound in cubic system is confirmed by a preliminary structural analysis using X-ray diffraction data. Energy dispersive spectrum analysis of Na₂MoO₄ has confirmed its chemical formula and composition. Spectroscopic studies of the compound have been carried by a vibration spectroscopy (Raman/FTIR) in order to understand its molecular structure at microscopic level. The complex impedance spectroscopy technique has been used to study the electrical properties of the material as a function of frequency (10²–10⁶ Hz) at different temperatures (23–450 °C), and also to investigate the fundamental mechanism involved in the material. Impedance analysis also indicates that below 300 °C, the material electrical conduction is related to the grain volume. Above 300 °C, the contribution of grain boundary is clearly evident. The electrical processes in the material are found to be temperature-dependent, and due to relaxation phenomena in it. A frequency dependent maximum of the imaginary electrical impedance is found to obey an Arrhenius law with activation energy of 1.07 eV. The frequency dependence of electrical conductivity spectra does follow the universal power law.