Magnetic property study of Gd doped TiO2 nanoparticles

In this work we have studied the magnetic properties of sol-gel synthesized Gd doped TiO2 nanoparticles. The Gd concentration varying from 0.03 to 0.07 mol. Structural, morphological and compositional analyses have been monitored with X-ray diffraction, transmission electron microscope (TEM), Raman spectroscopy and energy dispersive X-ray (EDX) spectroscopy. XPS spectra establish that Gd ions are in the +3 oxidation state. Photoluminescence intensity enhances at 0.03 and 0.05 mol and then quenches at 0.07. This is likely due to the formation of emission quenching centers. All the samples exhibit paramagnetism at room temperature as well as at 10 K. It is observed that due to the shielding of 4f shell of Gd3+ ions by 6s5d shell the direct exchange interaction of these Gd3+ ions with other Gd3+ ions is weak. These non-interacting and localized magnetic spins of Gd3+ induce only paramagnetism. The high magnetization exhibited by the samples at 10 K is due to minimization of the thermal randomization of the magnetic spins. Antiferromagnetic interaction persists at 0.03 mol and it gets stronger at 0.07 mol. Antiferromagnetism appears due to strong superexchange interaction of Gd3+ ions via O-2 -ions. (C) 2014 Elsevier B.V. All rights reserved.