New investigation of nanosized co-doped Gd-Sm anatase TiO2 structural, magnetic, optical, and first-principles study

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2020, Vol.126 (9), Article 721
• Main Authors: Guetni, Inssaf, Belaiche, Mohammed, Ahmani Ferdi, Chouaib, Elansary, Moustapha, Bsoul, Ibrahim
• Format: Article
• Language: English
• Subjects: Absorption spectra; Anatase; Applied physics; Banded structure; Characterization and Evaluation of Materials; Condensed Matter Physics; Conduction bands; Crystal defects; Crystallites; Electromagnetic absorption; Energy levels; Ferrimagnetism; First principles; Fourier transforms; Gadolinium; Infrared spectra; Investigations; Lattice vacancies; Lattice vibration; Machines; Magnetic measurement; Magnetic properties; Manufacturing; Materials science; Metal ions; Nanoparticles; Nanotechnology; Optical and Electronic Materials; Optical properties; Physics; Physics and Astronomy; Processes; Raman spectroscopy; Rare earth elements; Samarium; Sol-gel processes; Spectrum analysis; Surfaces and Interfaces; Thin Films; Titanium dioxide
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-020-03919-2

For the time we investigated the structural, optical and magnetic properties of (Sm, Gd) co-doped TiO 2 anatase nanoparticles, in addition to Sm-doped TiO 2 anatase nanoparticles using sol–gel method. The X-ray diffraction confirmed the single phase of tetragonal anatase with space group I4 1 /amd, where the crystallite size was found 7.2 nm and 8.8 nm for Ti 0.99 Sm 0.01 O 2 and Ti 0.99 Sm 0.005 Gd 0.005 O 2, respectively. The Fourier-transform infrared spectra showed the basic absorption bands in tetragonal anatase structure with a stretching vibration around 500 cm −1 assigned to Ti–O–M, M = (Gd, Sm). Raman spectroscopy demonstrated the presence of the six active vibrational modes for anatase TiO 2 . Scanning electron microscopy analysis revealed that the particles are spherical in nature and agglomerated. Energy-dispersive X-ray spectroscopy confirmed the high purity of the as-prepared materials. The UV–VIS analysis showed absorption in visible range, due to the electronic transition, which has been confirmed theoretically, also a slight decrease in the band gap was noticed compared to the pure TiO 2 anatase. The magnetic measurements reveal the existence of weak ferro or ferrimagnetic behavior. In this work, it is the first time that experimental and theoretical results prove that rare earth ions are incorporated into the sites of the TiO 2 lattice without the formation of separate phases. In addition, the experimental work carried out has revealed the importance of surface area, crystallinity, light absorption, the presence of oxygen vacancies and structural defects on the magnetic and more particularly optical properties with the highlighting of the intermediate energy level between the valence and conduction bands. This study was complemented by first-principles calculations to investigate the effects of doping anatase TiO 2 with the rare-earth elements Sm and Gd on its structural, optical and magnetic properties.