TY - JOUR

T1 - Magnetism and EPR Spectroscopy of Nanocrystalline and Amorphous TiO2: Fe upon Al Doping

AU - Yermakov, Anatoly

AU - Uimin, Mikhail

AU - Borodin, Kirill

AU - Minin, Artem

AU - Boukhvalov, Danil

AU - Starichenko, Denis

AU - Volegov, Alexey

AU - Eremina, Rushana

AU - Yatsyk, Ivan

AU - Zakharova, Galina

AU - Gaviko, Vasiliy

N1 - This work is financially supported by the RFBR Grant #20-02-00095 and partly by the Ministry of Science and Higher Education of the Russian Federation (theme “Magnet”, project No. 122021000034-9). Electron spin resonance measurements (Rushana Eremina, Ivan Yatsyk) were performed with the financial support from the government assignment for FRC Kazan Scientific Center of RAS.

PY - 2023

Y1 - 2023

N2 - This work is devoted to the study of the magnetic properties and Electron Paramagnetic Resonance (EPR) spectroscopy of TiO2:Fe nanoparticles doped with Al in different structural states. The sol-gel methods have been used to obtain the particles in both crystalline (average size from 3 to 20 nm) and X-ray amorphous states. The electron paramagnetic resonance spectra of crystalline samples TiO2:Fe doped with aluminum besides a resonance line with g-factor ~2 exhibit a small signal with a g-factor of 4.3 from Fe3+ ions with rhombohedral distortions. The fraction of Fe3+ with rhombohedral distortions increases with increasing aluminum content. For the amorphous state at Al doping, the resonance with a g-factor of 4.3 is completely dominant in the electron paramagnetic resonance spectrum. The density functional theory calculation shows that aluminum prefers to be localized near iron ions, distorting the nearest Fe3+ environment. The complex integral electron paramagnetic resonance spectrum of all samples was fitted with sufficient accuracy by three separate resonance lines with different widths and intensities. The temperature behavior of the electron paramagnetic resonance spectrum can be described by the coexistence of paramagnetic centers (isolated Fe3+ ions including dipole-dipole interactions) and iron clusters with negative exchange interactions.

AB - This work is devoted to the study of the magnetic properties and Electron Paramagnetic Resonance (EPR) spectroscopy of TiO2:Fe nanoparticles doped with Al in different structural states. The sol-gel methods have been used to obtain the particles in both crystalline (average size from 3 to 20 nm) and X-ray amorphous states. The electron paramagnetic resonance spectra of crystalline samples TiO2:Fe doped with aluminum besides a resonance line with g-factor ~2 exhibit a small signal with a g-factor of 4.3 from Fe3+ ions with rhombohedral distortions. The fraction of Fe3+ with rhombohedral distortions increases with increasing aluminum content. For the amorphous state at Al doping, the resonance with a g-factor of 4.3 is completely dominant in the electron paramagnetic resonance spectrum. The density functional theory calculation shows that aluminum prefers to be localized near iron ions, distorting the nearest Fe3+ environment. The complex integral electron paramagnetic resonance spectrum of all samples was fitted with sufficient accuracy by three separate resonance lines with different widths and intensities. The temperature behavior of the electron paramagnetic resonance spectrum can be described by the coexistence of paramagnetic centers (isolated Fe3+ ions including dipole-dipole interactions) and iron clusters with negative exchange interactions.

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UR - http://www.scopus.com/inward/record.url?partnerID=8YFLogxK&scp=85146772903

U2 - 10.3390/magnetochemistry9010026

DO - 10.3390/magnetochemistry9010026

M3 - Article

VL - 9

JO - Magnetochemistry

JF - Magnetochemistry

SN - 2312-7481

IS - 1

M1 - 26

ER -