Structural modification, photoluminescence, and magnetic property enhancement with Er3+ doping, of sol–gel TiO2 thin films

Abstract

Nanocrystalline undoped and Er3+ doped TiO2 thin films were prepared by sol–gel dip-coating technique onto glass substrates. Post-deposited films were annealed at 450 °C for 1 h. Differential scanning calorimetric analysis showed that undoped film crystallization occurred at 339 °C, while it appears at lower temperature for Er:TiO2. X-ray diffraction and Raman spectroscopy results indicate that the films crystallize only into anatase phase, and the crystallite size decreases from 24.3 to 21.16 nm with increasing Er3+ doping ratio. The photoluminescence (PL) spectra are composed of two broad peaks at 520–570 nm and 640–680 nm assigned to (2H11/2, 4S3/2)–4I15/2 and 4F9/2–4I15/2 transitions of Er3+ ions, respectively. PL emission intensities increase gradually raising the erbium doping ratio. Vibrating sample magnetometer results of undoped TiO2 thin films reveal a ferromagnetic behavior at room temperature and erbium doping leads to an enhancement of the saturated magnetic moment (Ms).