Compositional dependence of structural properties and bandgap of Mg-Co spinel nanoferrite.

Compositional dependence of structural properties, bandgap energy of sol-gel auto-combustion synthesized Mg1- xCoxFe2O4 (x = 0.0 – 1.0) spinel nano ferrites is studied by XRD (X-ray diffraction), Ultraviolet-visible (Uv-Vis) spectroscopy. Formation of spinel nano ferrire with grain diameter: 33.5 - 41.1 nm is confirmed by XRD measurements, which also shows presence of small amount of α-Fe2O3 phase. Increasing Co-content: a) increases x-ray density, crystallite size (range between 33.5−51.1 nm), and shows expansion of unit cell, b) shows linear increase of specific surface area, considerable variation in both strain, dislocation density, c) modifies the cationic distribution with Mg2+, Co2+, Fe3+ ions reside on both on A, B sites, and shows increase of Co2+, Fe3+ population via a simultaneous decrease of Mg2+ population at B−site, plays a key-role in determining Néel magnetic moment, d) displays higher degree of inversion (range between 0.55 - 0.95), and reveal higher disorder due to displacement of oxygen anion, e) affects A-O-A, A-O-B, B-O-B super-exchange interaction, affecting Néel magnetic moment, f) leads to fine tuning of energy bandgap (range between 1.90−2.0 eV), displays exponential decay of energy bandgap with increasing crystallite size, and linear decrease of bandgap with increasing Fe3+ ions on B-site. Bandgap ~ 2eV suggests their potential application as a suitable material for water purification via visible-light assisted photocatalysis for organic pollutants degradation. [ABSTRACT FROM AUTHOR]