Ferromagnetic Properties of N-Doped and Undoped TiO(2) Rutile Single-Crystal Wafers with Addition of Tungsten Trioxide

In this work, undoped, N-doped, WO(3)-loaded undoped, and WO(3)-loaded with N-doped TiO(2) rutile single-crystal wafers were fabricated by direct current (DC) magnetron sputtering. N-doping into TiO(2) and WO(3) loading onto TiO(2) 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 WO(3) 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 WO(3). UV-Vis spectrometer results showed that the absorption edge of WO(3)-loaded undoped and WO(3)-loaded with N-doped TiO(2) 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 WO(3) loading onto TiO(2) surface. The magnetic properties of the samples were investigated, and the saturation magnetization values were in the order N-doped > WO(3)-loaded with N-doped > undoped > WO(3)-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 WO(3)-loaded decreased the saturation magnetization values. This paper reveals that the magnetic properties of WO(3)-loaded with N-doped rutile single-crystal wafers originate from oxygen vacancies.