Structural, Optical, and Magnetic Properties of Lead-Free Ferroelectric Bi 0.5 K 0.5 TiO 3 Solid Solution with BiFeO 3 Materials

A solid solution of Bi 0.5 K 0.5 TiO 3 -BiFeO 3 was fabricated by a sol–gel technique. The pure Bi 0.5 K 0.5 TO 3 samples exhibited weak room-temperature ferromagnetism. The room-temperature ferromagnetism was observed in BiFeO 3 solid solution in Bi 0.5 K 0.5 TiO 3 . The optical band gap of Bi 0.5 K 0.5 TiO 3 was reduced from 3.22 eV to 1.39 eV with the increase in the amount of BiFeO 3 solid solution. The room-temperature ferromagnetism and band gap reduction were attributed to the diffusion of BiFeO 3 into Bi 0.5 K 0.5 TiO 3 to form a solid solution. Our work provided a simple method of realizing room-temperature ferromagnetism in lead-free ferroelectric materials.