Observation of room temperature ferromagnetism and magneto-electric coupling in dual transition element substituted ferroelectric potassium sodium niobate

In this work, we established multiferroic and magnetoelectric (ME) coupling characteristics in ferroelectric potassium sodium niobate K0.5Na0.5NbO3 (KNN) ceramics by substitution of dual transition metal (TM) ions such as Fe, Co. Powder X-ray diffraction (PXRD) patterns of all the compositions show characteristic doublet reflections of orthorhombic structure similar to pristine KNN with variations in the lattice parameters. Selected area electron diffraction pattern (SAED) also confirms crystallization of single-phase (Orthorhombic, Amm2) without any formation of Fe and/or Co clusters, Fe2O3, CO3O4. The di-, tri- and tetravalent oxidation states of TM ion and intensification of O2- vacancies with the increase in TM ion concentration have been examined from XPS analysis. These ceramic samples exhibited enhanced ferromagnetic and ferroelectric properties simultaneously at room temperature. Remarkably, the ME coupling is achieved in single-phase ferroelectric K0.5Na0.5NbO3 through co-substitution of Fe and Co ions.