BaNb2O6 at Room Temperature by Ball Milling Method: Structural, Optical, Morphology, and Electrochemistry Properties

Abstract

Materials that depend on high temperature, pressure, or long periods of crystallization in the obtention of the pure phase have been the focus of several studies due to the economic and ecological aspects. The high-energy ball milling method (HEBM) has been adopted to synthesize different materials using solid-state reactions. In this study, bare barium niobate was efficiently synthesized at room temperature using the HEBM. The materials synthesized at different synthesis times were characterized by X-ray diffraction (XRD) and Rietveld refinement, which confirms the orthorhombic structure for BaNb2O6, with a high crystallinity degree at 3 h (BaNb_3) and 4 h (BaNb_4) of synthesis. The main vibrational modes of the structure were identified by Raman spectroscopy. In contrast, band-gap values between 3.77 and 3.84 eV were obtained by diffuse reflectance spectroscopy for the samples BaNb_3 and BaNb_4, respectively. The electrochemical experiments using the modified glassy carbon electrode (GCE) with BaNb_3 sample as a working electrode show the almost reversible profile for the cyclic voltammetry curves in potassium ferrocyanide in the scanning speed range of 1 to 100 mV s-1. Moreover, the flat band energy (Efb) indicates the p-type semiconductor characteristic for BaNb2O6, and a specific capacitance of 3375.66 mF cm-2, suggesting an interesting material for composition n-p heterojunctions.