Magnetic Properties of (1 − x)Bi0.5Na0.5TiO3 + xCaCoO3−δ Solid-Solution System

Abstract

The (1 − x)Bi0.5Na0.5TiO3 + xCaCoO3−δ solid-solution system has been fabricated by a simple sol–gel route. X-ray diffraction analysis and Raman scattering measurements were performed to determine the structure of the solid-solution system. The samples were polycrystalline and had perovskite structure with rhombohedral symmetry. With increasing concentration of CaCoO3−δ solid solution in the host Bi0.5Na0.5TiO3, the optical bandgap reduced from 3.06 eV for pure Bi0.5Na0.5TiO3 to 2.15 eV for 9 mol.% CaCoO3−δ-modified Bi0.5Na0.5TiO3. This process also suppressed the photoluminescence of the host Bi0.5Na0.5TiO3. Weak ferromagnetism as well as diamagnetism were observed for pure Bi0.5Na0.5TiO3, changing to ferromagnetism and finally compensated ferromagnetism versus paramagnetism and/or antiferromagnetic-like behavior as the concentration of CaCoO3−δ was increased. Such introduction of ABO3 impurities containing alkaline-earth and transition metals into the host Bi0.5Na0.5TiO3 could therefore enhance the magnetic properties of this lead-free ferroelectric material to produce multiferroic materials for use in smart electronic devices.