Role of Co dopants on the structural, optical and magnetic properties of lead-free ferroelectric Na0.5Bi0.5TiO3 materials

Abstract

Co-doped Na0.5Bi0.5TiO3 materials were fabricated by a sol-gel technique. The structural distortion of Co-doped Na0.5Bi0.5TiO3 materials was due to the difference between the radii of Co dopants and Ti hosts. The optical band gap decreased from 3.11 to 1.83 eV because of the local state of the Co cation in the band structure. Room temperature ferromagnetism emerged as compensation of diamagnetic background and possibly intrinsic ferromagnetic signals. The magnetic moment was determined to be ∼0.64 μB/Co at 5 K. The origin of the room temperature ferromagnetism in the Co-doped Na0.5Bi0.5TiO3 materials was also investigated through the first-principles calculation method. Our study provides physical insights into the complex magnetic nature of transition metal-doped ferroelectric perovskites and contributes to the integration of multifunctional materials into smart electronic devices. Keywords: Lead-free ferroelectric, Multiferroics, Na0.5Bi0.5TiO3, Ferromagnetism, Sol-gel