Bi0.9Ho0.1FeO3/TiO2 Composite Thin Films: Synthesis and Study of Optical, Electrical and Magnetic Properties

A visible light active Bi0.9Ho0.1FeO3 nanoparticles/TiO2 composite thin films with different mol.% of Bi0.9Ho0.1FeO3 were successfully prepared via non-aqueous sol-gel method. The incorporation of 5, 10 and 20 mol.% Bi0.9Ho0.1FeO3 nanoparticles in the precursor solution of TiO2 brings modifications in the functional properties of the composite thin films. XPS analysis indicates that interdiffusion of Fe3+, Ho3+, Bi3+/Ti4+ ions through the interfaces between Bi0.9Ho0.1FeO3 nanoparticles and TiO2 matrix reduces the concentration of Ti3+ ions. X-ray diffraction analysis affirms that TiO2 and Bi0.9Ho0.1FeO3 retain anatase and orthorhombic phase respectively in composite films. The composite thin film containing 20 mol.% Bi0.9Ho0.1FeO3 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 TiO2 (3.4 eV). Hall effect measurements confirm that the resistivity of composite film increases by similar to 2.33 orders of magnitude and its carrier concentration decreases by 1.8 orders of magnitude at 5 mol.% Bi0.9Ho0.1FeO3 nanoparticles addition compared to those of pure TiO2 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.