A review on spinel chromites and their composites: Synthesis, characterization, and applications

Spinel chromite nanoparticles are highly attractive due to their unique structural, magnetic, optical, and catalytic properties. This review presents an overview of pure and doped spinel chromite with the standard chemical formula ACr 2 O 4 (A = Mg, Ni, Co, Cu, Zn), focusing on the effects of cation substitution at tetrahedral (A) and octahedral (B) sites on their structural and functional behaviour. Various synthesis methods including sol-gel, green synthesis, solid-state, microwave-assisted, and ball milling are summarized, highlighting their impact on particle size, morphology, and crystallinity. Characterization techniques such as XRD, SEM, TEM, PL, UV-Vis., FTIR, and VSM have been carried out to study structural, morphological, optical, electrical, and magnetic properties. The review also emphasizes applications spinel chromites in photocatalysis, gas sensing, antimicrobial activity, and energy storage. Overall, this work provides a clear roadmap for future research and development of spinel chromite-based functional materials.