Synthesis and characterization of TiO2– Bi0.9Ho0.1FeO3 composite thin film

Abstract

A visible light active TiO2 - Bi0.9Ho0.1FeO3 nanoparticles 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. X-ray diffraction analysis confirms that TiO2 and Bi0.9Ho0.1FeO3 retain anatase and orthorhombic phase respectively in composite films. Field emission scanning electron microscopy reveals that small clusters of Bi0.9Ho0.1FeO3 nanoparticles are distributed throughout the TiO2 matrix. 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 affirm 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.% Bi0.9Ho0.1FeO3 nanoparticles addition compared to the pure TiO2 film. Moreover, the pure film exhibits diamagnetism, whereas the composite films have both large ferromagnetic and small diamagnetic components. The diamagnetic susceptibility of composite films decreased 4.8 times compared to pure one at 20 mol. % Bi0.9Ho0.1FeO3 addition