Bi 0.9 Ho 0.1 FeO 3 /TiO 2 Composite Thin Films: Synthesis and Study of Optical, Electrical and Magnetic Properties

Abstract

A visible light active Bi 0.9 Ho 0.1 FeO 3 nanoparticles/TiO 2 composite thin films with different mol.% of Bi 0.9 Ho 0.1 FeO 3 were successfully prepared via non-aqueous sol-gel method. The incorporation of 5, 10 and 20 mol.% Bi 0.9 Ho 0.1 FeO 3 nanoparticles in the precursor solution of TiO 2 brings modifications in the functional properties of the composite thin films. XPS analysis indicates that interdiffusion of Fe 3+ , Ho 3+ , Bi 3+ /Ti 4+ ions through the interfaces between Bi 0.9 Ho 0.1 FeO 3 nanoparticles and TiO 2 matrix reduces the concentration of Ti 3+ ions. X-ray diffraction analysis affirms that TiO 2 and Bi 0.9 Ho 0.1 FeO 3 retain anatase and orthorhombic phase respectively in composite films. The composite thin film containing 20 mol.% Bi 0.9 Ho 0.1 FeO 3 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 2 (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.% Bi 0.9 Ho 0.1 FeO 3 nanoparticles addition compared to those of pure TiO 2 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.