From cation flexibility to multifaceted industrial adoptability: a voyage to the resourceful spinel*

ABSTRACTSignature of cation flexibility associated with the order–disorder structure of three spinel families, namely aluminates (MgAl2O4/ZnAl2O4), ferrites (NiFe2O4/ZnxNi1− xFe2O4), and titanate (Li4Ti5O12) was probed using the X-ray diffraction and Raman spectroscopy. Cation flexibility (also known as antisite defects or (dis)order structural transitions) is a unique feature of many oxide AB2O4 spinel systems in which the cations exchange their sites under external influence. This feature generates functionality in many different ways. In some cases, such as ferrites, the flexibility of zinc to occupy tetrahedral sites enhances the magnetic properties, whereas the flexibility of lithium in lithium titanate brings exotic electrochemical feature with zero strain. Similarly, cation flexibility of magnesium and aluminium makes the structure tolerant towards nuclear irradiation. Some such salient features of spinel systems are described highlighting the underlying crystal structures.Enriched with enormous ch...