Sodium Tungstate Particles’ Characterizations and Morphology

In organic chemistry, sodium tungstate (Na₂WO₄) is used as a catalyst for the epoxidation of alkenes and the oxidation of alcohols to aldehydes or ketones, and sodium tungstate particles are also known for their anti-diabetic effects; researchers have identified pathways by which sodium tungstate improves pancreatic function and beta-cell proliferation.

This sample, Na₂X_nO3_n+1, has been studied for a long time to understand its physical and chemical behavior, such as structural, phase transition, and vibrational investigations.

Sodium tungstate particles were prepared using a solid-state reaction in a study conducted by the Laboratory of Spectral Properties and Optical Materials of the Faculty of Sciences of the University of Sfax, Tunisia. This study reports the electrical properties and the conduction mechanism of the impedance spectra of Na₂WO₄ prepared by solid-state methods at 630 K.

In addition, the results show for the first time the optical properties of a Na₂WO₄ sample in the 200-2200 nm range using a spectroscopic ellipsometer (SE) with 1 nm steps, based on a new amorphous dispersion formulation at room temperature, by means of the DELTA PSI2 software.

In this research work, the Na₂WO₄ compound that has been synthesized was identified by XRD and the sample was found to crystallize with cubic symmetry in the Fd-3m space group. IR and Raman spectra were recorded and interpreted according to the structural features of WO₄^-2.

Interestingly, two semicircles were observed in the impedance diagram, indicating the presence of two relaxation processes associated with grains and grain boundaries in the studied compound. Thus, an equivalent circuit for the electrochemical cell of Na₂WO₄ is proposed.

The average particle size of the sample was measured to be approximately 33.3 nm using XRD analysis based on the W-H method. The roughness was found to be about 59.7 nm, while SEM images showed the nanoparticle size of this sample. EDX studies were used to analyze the composition of this sample, and TEM analysis was used to determine the particle diameter of about 600 nm.

Finally, the optical properties of sodium tungstate particles have been demonstrated using SE measurements and spectrophotometry (integrating sphere) in the spectral range 200-2200 nm at room temperature. The results obtained from SE (EXP and FIT) for this study show a good agreement. In addition, the optical bandgap of the Na₂WO₄ sample has been calculated by SE and confirmed by spectrophotometric measurements, also in good agreement.

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