Structural, Morphological and Electrochemical Properties of NaFeO₂ Synthesized by Solar Melting
Abstract
This paper presents the synthesis of tetragonal sodium ferroxide (NaFeO₂) via a solar-furnace melting method. The resulting material is characterized by a quasi-spherical morphology, an average particle size of ~1.2 μm, high crystallinity (⁓ 92%), and a polydisperse distribution, which ensures efficient transport pathways and uniform electrolyte penetration. SEM analysis revealed the formation of porous aggregates of nanogranular particles (200-500 nm) with a developed specific surface area (5-10 m²/g). DTA/TGA demonstrates multistage thermal transformations of the Na₂CO₃+Fe₂O₃ system with the formation of NaFeO₂ at 800-850 °C, confirming the thermal stability of the material. X-ray diffraction analysis confirmed the high crystallinity of the tetragonal phase with parameters a=4.47 Å, c = 14.4 Å, and a coherent scattering region size of ⁓ 28 nm. The obtained data indicate the high structural stability and electrochemical activity of NaFeO₂, making it promising for use in sodium-ion batteries.