Characterization of Ni-doped TiO₂ thin films deposited by dip-coating technique

¹ Laboratoire de Génie Energétique et Génie Informatique, Université Ibn Khaldoun, Tiaret, Algeria
² Laboratoire de Génie Physique, Université Ibn-Khaldoun, Tiaret, Algeria
³ Laboratoire de Stockage et Valorisation des énergies Renouvelables, USTHB, Alger, Algeria

^a e-mail: kharoubilmd@hotmail.fr

Received: 1 June 2015
Revised: 30 September 2015
Accepted: 23 October 2015
Published online: 1 December 2015

Abstract

Undoped and Ni-doped TiO₂ thin films have been prepared by sol-gel dip-coating method on glass and silicon substrates. X-ray diffraction studies show that both TiO₂ and Ni-doped TiO₂ thin films are of anatase phase with (1 0 1) as preferential orientation. From the UV-visible spectroscopy analysis, all films exhibits a high transparency ~ 80% and shows that the optical band gap decreases from 3.66 to 3.59 eV, which may be related with the phase composition and impurities. Fourier transformed infrared spectroscopy (FTIR) study confirms the presence of Ti-O, Ti=O and O-H bands. Thermal analysis by differential scanning calorimetriy (DSC) shows endothermic reactions between 30 °C and 280 °C and exothermic reactions between 370 °C and 540 °C corresponding to the crystallization of TiO₂ in the anatase phase. The Nyquist plots suggests that the equivalent circuit of the films is an R_pC_p parallel circuit and shows an increase in resistance R_p with increasing the Ni concentration and a decrease in capacity C_p.