Enhanced room temperature ferromagnetism in YMnO₃-modified lead-free ferroelectric Bi_0.5Na_0.5TiO₃ materials

The strongly enhanced room temperature ferromagnetism in Bi0.5Na0.5TiO3 materials was obtained via modification of YMnO3 as solid solutions. The weak ferromagnetism in pure Bi0.5Na0.5TiO3 was changed to ferromagnetism and antiferromagnetic-like with increasing the concentration of YMnO3 addition. The maxima magnetic moment was estimated at around 28.4 memu/g for 9 mol.% YMnO3-modified Bi0.5Na0.5TiO3 as a solid solution. The reduction of the optical bandgap energy from 3.18 eV to 2.01 eV was obtained via increasing YMnO3 addition into host Bi0.5Na0.5TiO3 crystal as solid solutions with amounts up to 9 mol.%. We suggested that the observation in the reduction of optical bandgap energy and great enhancement of the magnetic moment in YMnO3-modified Bi0.5Na0.5TiO3 compounds were strongly related to the random distribution of Y and Mn cations into the host lattice of Bi0.5Na0.5TiO3 crystals. We expected that our work will provide a simple way to integrate room temperature ferromagnetism into currently developed green ferroelectric materials.