BiHoFeO/TiO Composite Thin Films: Synthesis and Study of Optical, Electrical and Magnetic Properties.

A visible light active BiHoFeO nanoparticles/TiO composite thin films with different mol.% of BiHoFeO were successfully prepared via non-aqueous sol-gel method. The incorporation of 5, 10 and 20 mol.% BiHoFeO nanoparticles in the precursor solution of TiO brings modifications in the functional properties of the composite thin films. XPS analysis indicates that interdiffusion of Fe, Ho, Bi/Ti ions through the interfaces between BiHoFeO nanoparticles and TiO matrix reduces the concentration of Ti ions. X-ray diffraction analysis affirms that TiO and BiHoFeO retain anatase and orthorhombic phase respectively in composite films. The composite thin film containing 20 mol.% BiHoFeO nanoparticles exhibits the most prominent absorption phenomenon in visible region and has significantly reduced indirect band gap of 2.46 eV compared to that of pure TiO (3.4 eV). Hall effect measurements confirm that the resistivity of composite film increases by ∼2.33 orders of magnitude and its carrier concentration decreases by 1.8 orders of magnitude at 5 mol.% BiHoFeO nanoparticles addition compared to those of pure TiO film. Moreover, the pure film exhibits diamagnetism, whereas the composite films have both large ferromagnetic and small diamagnetic components. The findings in this research justify that the composite film can be a potential candidate for making improved photocatalyst, resistors and spintronic devices.