Ferromagnetic Properties of N-Doped and Undoped TiO2 Rutile Single-Crystal Wafers with Addition of Tungsten Trioxide

Abstract

In this work, undoped, N-doped, WO3-loaded undoped, and WO3-loaded with N-doped TiO2 rutile single-crystal wafers were fabricated by direct current (DC) magnetron sputtering. N-doping into TiO2 and WO3 loading onto TiO2 surface were used to increase and decrease oxygen vacancies. Various measurements were conducted to analyze the structural and magnetic properties of the samples. X-ray diffraction results showed that the N-doping and WO3 loading did not change the phase of all samples. X-ray photoelectron spectroscopy results revealed that W element loaded onto rutile single-crystal wafers existed in the form of WO3. UV-Vis spectrometer results showed that the absorption edge of WO3-loaded undoped and WO3-loaded with N-doped TiO2 rutile single-crystal wafers had red shift, resulting in a slight decrease in the corresponding band gap. Photoluminescence spectra indicated that oxygen vacancies existed in all samples due to the postannealing atmosphere, and oxygen vacancies density increased with N-doping, while decreasing with WO3 loading onto TiO2 surface. The magnetic properties of the samples were investigated, and the saturation magnetization values were in the order N-doped > WO3-loaded with N-doped > undoped > WO3-loaded undoped rutile single-crystal wafers, which was the same order as the oxygen vacancy densities of these samples. N-doping improved the saturation magnetization values, while WO3-loaded decreased the saturation magnetization values. This paper reveals that the magnetic properties of WO3-loaded with N-doped rutile single-crystal wafers originate from oxygen vacancies.

Architecture of a Long-Wavelength Visible–Light–Driven N-Doped WO3/BiVO4 Heterojunction Structure for Highly Efficient Photoelectrochemical Water Splitting

“…These XPS results indicate that nitrogen is successfully incorporated into the structure and exists in a chemically bonded state (indicating this type of nitrogen is an active doping species) . Combined with the related reports, the N-doped metal oxides (N-WO 3 and N-TiO 2 ), or metal nitrides exhibited a characteristic peak at 396.0 eV corresponding to the β-N state (associated with the bonding of metal centers with nitrogen). This is distinct from the characteristic peak formed due to N 2 insertion or metal center-nitrogen bonding.…”

Effect of Zr Doping on the Magnetic and Phase Transition Properties of VO2 Powder

“…A main peak appeared at 530.59 eV corresponding to a typical lattice O 2− absorption that has been reported for many metal oxides (e.g. TiO 2 and VO 2 ) [31,32]. A peak appeared with a BE of 532.56 eV was assigned to C=O and hydroxyl groups that probably result from contamination of sample [31].…”

“…TiO 2 and VO 2 ) [31,32]. A peak appeared with a BE of 532.56 eV was assigned to C=O and hydroxyl groups that probably result from contamination of sample [31]. In Figure 3c, two peaks appeared at BE of 182.31 eV and 184.75 eV which correspond to Zr 2p 3/2 and 2p 1/2 energy levels, respectively [33] Thus confirming that Zr 4+ had been effectively doped into the VO 2 lattice.…”