Strain‐Driven Lattice Distortion in Calcium‐Added (Co, Cu, Mg, Ni, Zn)O and its Electrical Properties

The field of high‐entropy oxides (HEOs) challenges traditional materials science paradigms by exploring material properties via tuning configurational disorder. This disorder arises from multiple elements occupying equivalent lattice sites, creating a vast range of possible elemental combinations. Such high configurational disorder often imbues HEOs with surprising functional properties, sometimes surpassing those of their more ordered counterparts. Calcium has been added to (Co, Cu, Mg, Ni, Zn)O to analyze the distortion in the lattice due to ionic size mismatch and investigate the effect of distortion on the frequency‐dependent dielectric properties and ionic conductivity. A simple scheme is utilized to characterize the distortion, while the true nature of the distortion is revealed using electron microscopy. X‐ray photoelectron spectroscopy and X‐ray absorption spectroscopy are utilized to get insight into the strain‐induced oxidation/reduction of cations due to large‐size Ca 2+ cation addition, which in turn enhances the dielectric constant and electrical conductivity.