Structural, optical and weak magnetic properties of Co and Mn codoped TiO2 nanoparticles

The present investigation focuses on the structural properties and magnetic response of Co, Mn and Co-Mn doped TiO2 nanoparticles (within 3% dilute doping) along with their optical and electrical studies. X-ray diffraction (XRD) patterns for all these samples show the formation of tetragonal TiO2 anatase phase with no extra impurity phases. Further, Raman bands at 143 cm(-1), 396 cm(-1), 516 cm(-1) and 639 cm(-1) also confirm the anatase phase in these samples. Diamagnetic response has been observed in pure TiO2 nanoparticles. However, room temperature (RT) ferromagnetism has been observed with Co and/or Mn doping which gets enhanced further with codoping of Co ions. The observed ferromagnetism has been attributed to the formation of shallow levels with doping/codoping. The Co and/or Mn-doped TiO2 nanoparticles are referred as diluted magnetic semiconductors due to their combined semiconducting and ferromagnetic response. UV-Vis spectra show the band gap of these samples are in the range of 3.03 eV-3.24 eV and a reduction in band gap is observed after codoping. The temperature dependent electrical conductivity measurements also show an enhancement in conductivity after codoping at RT. (C) 2017 Elsevier Masson SAS. All rights reserved.