This article summarizes the strain‐mediated electrical and optical properties of novel lead‐free xCuFe2O4 (1 − x) KNbO3 (x = 0.2, 0.3, and 0.4) multiferroic nanocomposite through a solid state route. X‐ray diffraction analysis divulges the influence of interfacial strain in the KNbO3–CuFe2O4 matrix and shows the coexistence of orthorhombic and cubic spinel phases, respectively. Morphological analysis reveals that the average particle size of 0.3CuFe2O4–0.7KNbO3 is 25 nm which is smaller than the other two nanocomposites. The UV–visible absorption studies and Raman spectroscopy of 0.3CuFe2O4–0.7KNbO3 nanocomposite present the high energy bandgap and electro coupling of KNbO3 and CuFe2O4 phases. The DFT theoretical bandgap behaviors of all the three nanocomposites synchronize with the experimental bandgap results. Dielectric, ferroelectric and magnetoelectric behaviors are also improved in 0.3CuFe2O4–0.7KNbO3 nanocomposite as compared to pristine KNbO3 and the other two nanocomposites. Highlights This article summarizes the strain‐mediated electrical and optical properties of novel lead‐free xCuFe2O4–(1 − x) KNbO3 (x = 0.2, 0.3, and 0.4) multiferroic nanocomposite through a solid state route. X‐ray diffraction analysis divulges the influence of interfacial strain in the KNbO3–CuFe2O4 matrix and shows the coexistence of orthorhombic and cubic spinel phases, respectively. The 0.3CuFe2O4–0.7 KNbO3 nanocomposite shows a remarkable increase in the optical bandgap, remnant polarization, dielectric permittivity, and magnetoelectric coefficient compared to the other two nanocomposites. DFT calculations on KNbO3–CuFe2O4 matrix reveal the impact of diffusion between two phases and support the bandgap experimental results.

The present work unveiled the distortion of oxygen octahedra influencing magnetic and magnetoelectric properties of novel Bi 1−x Er x Fe 1−y Zr y O 3 (x = 0, .05, .1, y = .02, .05) polycrystalline nanoparticles by sol-gel route. X-ray diffraction patterns analysis reveals that pristine BiFeO 3 and doped BiFeO 3 are crystalized in the rhombohedral structure (R3c). The Fe-O-Fe bond angle of Bi 1−x Er x Fe 1−y Zr y O 3 (x = 0, .05, .1, y = .02, .05) varies between 141 • and 159.62 • as the concentration of Er (via Bi site) and Zr (via Fe site) ions increases in BiFeO 3 . As a result, the tilt angle of oxygen octahedra and the canting angle of spiral spin arrangement increase. Hence, the maximum magnetization varies between .03144 and .37558 emu/g in Er and Zr co-doped BiFeO 3 system. The number of electrons per unit cell of Bi 1−x Er x Fe 1−y Zr y O 3 (x = 0, .05, .1, y = .02, .05) lies between 733.38 and 831, respectively. Further, the number of coherently diffracting domains increases from 3.07 to 5.21, and then it decreases when Er and Zr are increased in BiFeO 3 . Consequently, the magnetoelectric coupling coefficient varies between .0265 and .2511 mV/cm Oe, respectively. Particularly, Bi 0.95 Er 0.05 Fe 0.98 Zr 0.02 O 3 shows enhanced magnetic and magnetoelectric behaviors compared to other samples.