In ceramic oxide thin films, lattice strain is a powerful tool for engineering material properties. As the film conforms to the substrate's lattice, mismatches induce strain that reshapes the crystal structure and tunes the electronic band landscape, unlocking novel physical behaviors absent in the bulk form of ceramics. Herein, a comparative study between bulk and thin films of double perovskite oxides, Sr 2 FeCoO 6 (SFCO), Sr 2 FeMnO 6 (SFMO), and SrLaFeMnO 6 (SLFMO) on the background of crystal geometry and electronic structure is reported. The observed X‐ray patterns depict massive broadening in the peak features, which leads to high lattice strain (two fold to five fold) in the studied films. Compared to the bulk states, the electronic charge states of Fe and Co are pushed to lower oxidation states, while Mn prefers to lose electrons. Interestingly, in thin films, the Fe 2+ state is observed for SFMO and SLFMO, and Co 3+ is entirely converted into Co 2+ in SFCO, compared to their bulk counterpart. This study has broader implications concerning the role of lattice strain in influencing the geometrical configuration and the electronic structure, thereby affecting the structure‐sensitive functional properties.
Kumari et al. (2025) studied this question.