Experimental and theoretical studies on induced ferromagnetism of new (1 - x)Na0.5Bi0.5TiO3 + xBaFeO3-δ solid solution.

New solid solution of Na0.5Bi0.5TiO3 with BaFeO3-δ materials were fabricated by sol-gel method. Analysis of X-ray diffraction patterns indicated that BaFeO3-δ materials existed as a well solid solution and resulted in distortion the structure of host Na0.5Bi0.5TiO3 materials. The randomly incorporated Fe and Ba cations in the host Na0.5Bi0.5TiO3 crystal decreased the optical band gap from 3.11 to 2.48 eV, and induced the room-temperature ferromagnetism. Our density-functional theory calculations further suggested that both Ba for Bi/Na-site and Fe dopant, regardless of the substitutional sites, in Na0.5Bi0.5TiO3 lead to the induced magnetism, which is illustrated in terms of the exchange splitting between spin subbands through the crystal field theory and Jahn-Teller distortion effects. Our work proposes a simple method for fabricating lead-free ferroelectric materials with ferromagnetism property for multifunctional applications in smart electronic devices.